TWI594970B - ITO sputtering target and manufacturing method thereof, and manufacturing method of ITO transparent conductive film and ITO transparent conductive film - Google Patents

Description

ITO sputtering target and manufacturing method thereof, and ITO transparent conductive film and ITO transparent conductive film manufacturing method

This invention relates to an ITO sputtering target suitable for forming an ITO film. In particular, an ITO sputtering target having a small particle size, high density, high strength, arcing reduction and nodule, a method for producing the same, and a method for producing an ITO transparent conductive film and an ITO transparent conductive film . The main use of the present invention includes a touch panel, a flat panel display, an organic EL, and a solar cell.

In general, an ITO (indium-tin composite oxide) film is now widely used as a transparent electrode (conductive film) in a display element centered on a liquid crystal display. The method of forming the ITO film is carried out by a method generally called a physical vapor deposition method such as a vacuum deposition method or a sputtering method. In particular, from the viewpoint of workability or film stability, it is often formed by magnetron sputtering.

The film formation by sputtering means is carried out by causing a cation such as Ar ion to physically strike a target provided on the cathode, and the impact energy is used to release the material constituting the target so as to be substantially the same as the target material. The film of the composition is laminated on the opposite side of the substrate on the anode side. The coating method by the sputtering method has a feature that a film of several nm can be formed to a thick film of several tens of μm at a stable deposition rate by adjusting the processing time or supplying electric power.

In recent years, there has been a demand for an ITO film which is used for a capacitive type, a resistive film type touch panel, etc., except for a tin (Sn) containing about 10 wt.% which has been widely used. In addition to the ITO sputtering target, a target in which tin oxide is changed in a wide range of 1.0 or more and 50.0 wt.% or less in accordance with the required film resistance is being developed. For example, it is known in Patent Document 1 that a mixed powder of indium oxide containing 20 to 50% by weight of tin oxide is press-molded, and the molded body is in a pure oxygen atmosphere at a temperature of 1500 to 1650 ° C and a pressure of 0.15 to 1 MPa. Pressure sintering was performed to produce an ITO sputtering target.

A patent represented by the ITO sputtering target is disclosed in Patent Document 1 shown below. This patent is "an ITO sputtering target which is obtained by powder metallurgy using a raw material of indium oxide and tin oxide. The surface roughness Ra of the sputtering target is 0.5 μm or less and the density D (g/cm ^{3 ).} And the volume resistance value ρ (mΩcm) satisfies the following two equations, a) 6.20≦D≦7.23; b”-0.0676D+0.887≧ρ≧-0.0761D+0.666. ", about 20 years ago, the technology.

This patent can realize the following ITO sintered target, which can be called an epoch-making invention at that time. The ITO sintered target hardly generates abnormal discharge or nodule during sputtering, and the gas adsorption is extremely small. A high-quality ITO film can be stably obtained under a good film forming operation.

Further, as a measure for increasing the density of the ITO target, for example, Patent Document 2 listed below discloses an ITO target which is formed using the following tin oxide powder: a medium diameter of 0.40 (excluding 0.40) to 1.0 is obtained from the particle size distribution. The range of μm and the 90% particle diameter determined from the particle size distribution is in the range of 3.0 μm or less.

However, when such a tin oxide powder is used to produce an ITO target containing more tin oxide than in the prior art, micropores and microcracks may be generated inside the sintered body, and during processing or processing of the sintered body. Cracks or cracks occur during the preservation process after the end. Moreover, they may sometimes affect the shipment of target products.

Further, in the following Patent Document 3, as a technique related to ITO, there is disclosed a technique of providing an ITO sputtering target having a low bulk resistance, the ITO sputtering target being in In ₂ O ₃ as a main crystal grain. An ITO sintered body having fine particles composed of In ₄ Sn ₃ O ₁₂ in the mother phase, wherein the fine particles have a three-dimensional star shape, and the three-dimensional star shape is formed in a needle shape from a virtual center of the particle. Protrusion.

Further, Patent Document 4 discloses a technique of forming an ITO sintered body composed of In, Sn, and O, a sintered density of 7.08 g/cm ³ or more, and a volume resistivity of 80 μΩcm to 100 μΩcm, O/( In+Sn+O) is 1.75% or less (weight ratio), and the integrated intensity of the X-ray diffraction peak of the (200) plane of the In ₄ Sn ₃ O ₁₂ phase is 30% or less, and the sintered body is sintered by In, In the case of a molded body composed of Sn or O, when the sintering temperature is 1400 ° C or higher, the sintering environment is converted from an oxidizing environment to a non-oxidizing environment.

It is desirable to obtain a low-resistance film from ITO (tin oxide: 10 wt.%) which is usually used, and it is necessary to heat-treat at 150 ° C or higher, but it is also impossible to heat to 150 ° C. For example, when a transparent conductive film used in a touch panel or the like cannot be heated in a film formation or after film formation due to a structural problem, a low-oxidation film of a low-resistance film can be obtained even at a low temperature. ITO.

Since the ITO target composed of low tin oxide changes the existence of the tin-rich phase due to the sintering temperature, if the sintering temperature is not controlled, there arises a problem that it is difficult to increase the density and it is difficult to control the crystal grain size. Also in batches, sometimes the density will change. Moreover, it becomes easy to cause a problem that the dispersibility of the tin-rich phase is deteriorated, and protrusions or arcs are easily generated.

In the following Patent Documents 5 to 10, proposals have been made for an ITO sputtering target having a low tin oxide composition.

Patent Document 5 is characterized in that the tin oxide content is 1.5% or more and 3.5% or less by mass ratio, the relative density is 98% or more, the crystal phase is single phase, the average crystal grain size is 10 μm or less, and the bending strength of the sintered body is 70 MPa. the above. However, the sintering temperature is as high as 1500 ° C, and mixing the first granulated powder with the second granulated powder to form a molded body will be somewhat troublesome, and the productivity is not so good.

Patent Document 6 discloses an ITO sputtering target which is composed of indium oxide, tin oxide and unavoidable impurities, and has a tin oxide content of 2.5% by mass or more and 5.2% by mass or less, and an average density of 7.1 g/cm ³ or more. And the average crystal grain size is 3 μm or more and less than 10 μm. However, the temperature was maintained as high as 1500 to 1600 ° C, and the strength of the sintered body was not described.

Patent Document 7 discloses a sintered body of indium oxide and tin oxide, characterized in that the tin content is 3 to 12% by weight, and the solid solution amount of tin dissolved in the In ₂ O ₃ phase is 2% by weight or more, In The average crystal grain size of the phase in which the ₂ O ₃ phase and the tin element are dissolved in the In ₂ O ₃ phase is in the range of 2 to 10 μm, and the maximum pore diameter existing in the sintered body is 3 μm or less, and the maximum of the tin atoms. The coagulation diameter is below 5 μm. However, the sintering temperature was 1500 ° C or higher, and the average particle diameter in the examples and the comparative examples was as high as 7 μm or more, and the sintered body density was only 6.9 g/cm ^{3 at the} maximum. Also, there is no mention of the strength of the sintered body at all.

Patent Document 8 is a sintered body composed of indium, tin, and oxygen, characterized in that the amount of tin is 2 to 4 wt%, and the relative density is 90% or more, and the tin oxide phase and the intermediate compound phase other than the indium oxide phase are The single-phase structure with an area ratio of 5% or less has a specific resistance of 1 × 10 ^-3 Ω. Below cm. However, the sintering temperature is as high as 1500~1700 °C, and the specific resistance of the sintered body is also high.

Patent Document 9 is an ITO sintered body which is substantially composed of indium oxide and tin oxide, and has a tin oxide content of 35 wt% or less, a large area of 300 mm × 300 mm or more, and a thickness of 6 mm or more, and is characterized by: sintered density. at 7.13g / cm ³ or more, of the sintered body and the planar direction of the maximum density difference of ³ or less 0.03g / cm, and the average number of pores of 2μm or less in the direction of the thickness of the central portion 500 / mm ² or less, holding Sintering is performed at a sintering temperature of 1450 ° C or higher. However, the sintering temperature is as high as 1450 ° C or more, and the sintering method is also specified in detail, which cannot be said to be good in productivity.

Patent Document 10 discloses an ITO sputtering target which is composed of indium, tin, and oxygen, and contains a sintered body having a relative density of 99% or more and a thickness of 10 mm or more, and satisfies the following formula. (1) Formula (1): The relative density (%) of the central portion in the thickness direction of the sintered body / the density (%) of the entire sintered body ≧ 0.995. However, the sintering temperatures of the examples and the comparative examples were as high as 1600 ° C, and although the crystal grain size was not described, the crystal grain size was estimated to be large.

Further, none of the above-mentioned documents has been produced from the viewpoint of reducing the particle diameter and making the particle size small and high density and high strength by low-temperature sintering.

Patent Document 1: Japanese Patent No. 2750483

Patent Document 2: Japanese Patent Laid-Open Publication No. 2009-29706

Patent Document 3: Japanese Patent Laid-Open Publication No. 2009-40621

Patent Document 4: Japanese Laid-Open Patent Publication No. 2000-233969

Patent Document 5: Japanese Patent No. 5206983

Patent Document 6: Japanese Laid-Open Patent Publication No. 2012-126937

Patent Document 7: Japanese Patent Laid-Open No. Hei 10-147862

Patent Document 8: Japanese Patent No. 3503759

Patent Document 9: Japanese Patent No. 3984141

Patent Document 10: Japanese Patent No. 4934826

The present invention relates to an ITO sputtering target which can form a low-resistance film of a low-resistance film even at a low temperature, and provides a target having a small particle size, high density, high strength, and ITO sputtering which can reduce arc and protrusions. target. The problem is to improve film formation quality and ensure reliability.

In order to solve the above problems, the present invention provides the following invention.

1) A sputtering target which is a sintered body composed of In, Sn, O, and unavoidable impurities, and contains Sn/(In+Sn) in an atomic ratio of 1.8% or more and 3.7% or less (except for 3.7%) Sn, the average crystal grain size of the sintered body is in the range of 1.0 to 5.0 μm, and the pores having a major axis diameter of 0.1 to 1.0 μm are an area ratio of 0.5% or less, which is a phase of the indium oxide phase and the tin-rich phase. The area ratio of the tin oxide phase is 0.1 to 1.0%, and more than 95% of the tin oxide-rich phase exists at the grain boundary three junctions.

2) The sputtering target according to the above 1), which contains Sn in an atomic ratio of Sn/(In+Sn) of 2.3 to 3.2%.

The sputtering target according to any one of the above 1), wherein the sintered body has a sintered body density of 7.03 g/cm ³ or more and a volume resistivity of 0.10 to 0.15 mΩ. Cm.

4) The sputtering target according to any one of the above 1) to 3, wherein the maximum size of the tin-rich phase is 1 μm or less.

The sputtering target according to any one of the above 1) to 4, wherein the sputtering target has a bending strength of 100 MPa or more.

6) A method for producing an ITO sputtering target, which is a method for producing a sputtering target comprising In, Sn, O and unavoidable impurities according to any one of the above 1) to 5), wherein SnO ₂ powder and In are _{The 2} O ₃ powder is adjusted in such a manner that the atomic ratio of Sn/(In+Sn) is 1.8% or more and 3.7% (except for 3.7%), and the mixture is mixed, and the maximum sintering temperature is maintained at 1450 in an oxygen atmosphere. Sintering is carried out at a temperature below °C.

(7) The method for producing a sputtering target according to the above-mentioned item 6, wherein the ratio of the SnO ₂ powder to the In ₂ O ₃ powder is adjusted to be 2.3 to 3.2% by atomic ratio of Sn/(In+Sn). Mix and then sinter.

The method for producing a sputtering target according to the above 6) or 7), wherein the cooling step after the sintering is carried out at a temperature lower than the sintering holding temperature of 100 ° C ± 20 ° C.

9) A method for producing a transparent conductive film, which is a method for producing a transparent conductive film by sputtering, characterized in that in a mixed gas atmosphere composed of argon and oxygen and having an oxygen concentration of 4% or less, the substrate is not heated or The substrate is held at 150 ° C or lower, and the sputtering target described in any one of the above 1) to 5) is formed on the substrate.

With respect to an ITO sputtering target which is suitable for forming a transparent conductive film and which can obtain a low-resistance film of a low-resistance film even at a low temperature, it can provide a small particle size, high density, high strength, and can reduce arcs and protrusions. Sputter target. This ensures the improvement and reliability of film formation quality. As a result, it has an excellent effect of improving the productivity and reliability of the target.

Fig. 1 shows an ITO sintered body containing Sn in an atomic ratio of Sn/(In+Sn) at 3.8% using FE-EPMA (manufactured by JEOL Ltd., JXA-8500F FE electron probe microanalyzer) × 2000 times the surface analysis result of Sn.

Figure 2 is a diagram showing the presence of more than 95% of the tin-rich phase in the grain boundary three junctions (A, B, C, D).

Fig. 3 is a view showing a target image (photograph) and a projection coverage rate after 35 hr continuous sputtering.

Fig. 4 is a view showing a specific example of the observation site of the sintered body (in the case of a round sintered body, square sintering) Figure of the situation of the body, the case of the cylinder.

In the present invention, the sputtering target is a sintered body composed of In, Sn, O, and unavoidable impurities, and contains Sn/(In+Sn) in an atomic ratio of 1.8% or more and 3.7% or less (except that 3.7 is not included). %) Sn, the average crystal grain size of the sintered body is in the range of 1.0 to 5.0 μm, and the pores having a major axis diameter of 0.1 to 1.0 μm are 0.5% or less in area ratio, and become two phases of the indium oxide phase and the tin-rich phase. The area ratio of the tin-rich phase is 0.1 to 1.0%, and more than 95% of the tin-rich phase exists at the grain boundary three junctions.

The value of Sn in the atomic ratio of Sn/(In+Sn) is 1.8% or more and 3.7% or less (except that 3.7% is not included), and the lower limit is 1.8%. The reason is that if it is less than 1.8%, it is not There is a tin oxide rich phase. Further, the numerical value of the upper limit of 3.7% (except for 3.7%) is limited because the area ratio of the tin-rich phase is more than 1%. It is further more effective to contain Sn having an atomic ratio of Sn/(In+Sn) of 2.3 to 3.2%.

Further, the average crystal grain size of the sintered body must be in the range of 1.0 to 5.0 μm. When the average crystal grain size is less than 1.0 μm, the crystal grain size is too small, and there is a problem that the density cannot be increased. If it exceeds 5.0 μm, the sintered body has a problem that the bending strength of the sintered body is less than 100 MPa, which is not preferable.

In the sintered body, the area ratio of the pores having a major axis diameter of 0.1 to 1.0 μm is 0.5% or less because the existence of the pores causes not only a decrease in density, but also an arc due to residual gas or the like of the pores. Therefore, it is preferable to be as small as possible. Regarding the pores in the sintered body having a major axis diameter of less than 0.1 μm, it is not negligible because it does not affect the characteristics of the target. On the other hand, for a hole exceeding 1.0 μm, it must be left absent.

The structure of the sintered body becomes two phases of an indium oxide phase and a tin-rich phase. Based on the surface analysis by EPMA, the area ratio of the tin-rich phase must be 0.1 to 1.0%. In order to obtain a sintered body having a small average crystal grain size, the conditions required for the characteristics of the sputtering target of the present invention are obtained.

The invention of the present invention has more than 95% of the tin oxide-rich phase present at the grain boundary three joints as a requirement. (distributed uniformly on the target, the tin-rich phase exists in the state of the dispersed state at the grain boundary three junctions.) The "grain boundary three junctions" in this case means that the tin-rich phase exists in the collection of three mutual contacts. The approximate central portion of the particle. Although it will be described in detail later, if it is desired to form such a state (more than 95% of the tin-rich phase is present at the grain boundary three junctions), it must be at a temperature lower than the sintering holding temperature of 100 ° C ± 20 ° C in the cooling step. maintain.

The ITO sputtering target can further increase the density of the sintered body to 7.03 g/cm ³ or more, and the volume resistivity is 0.10 to 0.15 mΩ. Cm, improve conductivity. Further, the maximum size of the tin-rich phase is preferably 1 μm, and it is preferably a target which is suppressed from being coarsened by the tin-rich phase.

Further, it is preferable that the sintered body of the ITO sputtering target has a bending strength of 100 MPa or more and the strength of the target is increased, and the present invention can achieve the object.

When the sintered body ITO sputtering target comprising indium oxide, tin oxide and unavoidable impurities of the present invention is produced, the SnO ₂ powder and the In ₂ O ₃ powder have an atomic ratio of Sn/(In+Sn) of 1.8% or more. The ratio was adjusted by 3.7% or less (except for 3.7%), and the mixture was mixed, and the maximum sintering temperature was maintained at a temperature of 1,450 ° C or less in an oxygen atmosphere, and sintering was performed.

When the indium oxide-tin oxide-based oxide (ITO) sintered body target of the present invention is produced, it can be produced by mixing, pulverizing, molding, and sintering of each raw material powder. When indium oxide powder and tin oxide powder are used as the raw material powder, it is preferred to use 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 medium diameter (D ₅₀ ): 0.5 to 2.5 μm, a specific surface area of 3.0 to 6.0 m ² /g, and a tin oxide powder: body density: 0.2. ~0.6 g/cm ³ , medium diameter (D ₅₀ ): 1.0 to 2.5 μm, specific surface area: 3.0 to 6.0 m ² /g.

Each raw material powder is weighed to a desired composition ratio, and then mixed and pulverized. The pulverization method has various methods depending on the desired particle size and the pulverized material, and is preferably a wet medium agitating pulverizer such as a bead mill. The slurry in which the powder is dispersed in water is forcibly stirred together with a pulverizing medium such as zirconium dioxide or alumina which is a material having high hardness, and the pulverized powder can be obtained efficiently. However, since the pulverizing medium is also worn at this time, the pulverizing medium itself is mixed with the pulverized powder in the form of impurities, so that the treatment for a long time is not preferable.

When the amount of pulverization is defined by the difference in specific surface area before and after pulverization, the amount of pulverization in the wet medium agitating pulverizer is approximately proportional to the input energy to the powder. Therefore, it is important to manage the accumulated electric quantity of the wet medium agitating pulverizer when pulverizing. The difference (ΔBET) between the specific surface areas before and after the pulverization was 0.5 to 5.0 m ² /g, and the diameter (D ₅₀ ) after the pulverization was 2.5 μm or less.

Next, granulation of the finely pulverized slurry is performed. In order to improve 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. One of the methods of granulating and obtaining a granulated powder suitable for press molding has a method using a spray dryer. This is a method in which a powder is formed into a slurry, which is dispersed in hot air in the form of droplets, and is instantaneously dried to obtain a spherical granulated powder of 10 to 500 μm continuously.

Further, the strength of the molded body can be improved by adding a binder such as polyvinyl alcohol (PVA) to the slurry to be contained in the granulated powder. The amount of PVA added is 50 to 250 cc/kg of an aqueous solution containing 4 to 10 wt.% of PVA, based on the raw material powder.

Further, a plasticizer suitable for the binder is also added, whereby the crushing strength of the granulated powder at the time of press molding can be adjusted. Further, there is a method of adding a small amount of water to the obtained granulated powder to wet it, thereby increasing the strength of the molded body. In the drying with a spray dryer, the management of the inlet and outlet temperatures of the hot air is important.

If the temperature difference between the inlet and the outlet is large, the amount of drying per unit time will increase, and productivity will increase. However, when the inlet temperature is too high, the powder and the added binder may deteriorate due to heat. Unable to get the desired features. Further, 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 in a mold, and the pressure is maintained at 400 to 1000 kgf/cm ² for 1 to 3 minutes. If the pressure is less than 400 kgf/cm ² , a molded body having sufficient strength and density cannot be obtained. Further, when the pressure is 1000 kgf/cm ² or more, the molded body itself may be under pressure when the molded body is taken out from the mold. Liberation causes deformation and damage, which is not good in production.

The formed body is sintered in an oxygen atmosphere using an electric furnace to obtain a sintered body. Sintering is performed at a sintering temperature of 1,450 ° C or lower. In this case, when the sintering temperature exceeds 1450 ° C, the sintered body structure becomes a single phase, and the crystal grain size also coarsens. Therefore, the upper limit is preferably 1450 ° C. In the process of raising the temperature to the sintering temperature, the debonding agent step or the like may be introduced as needed.

When the holding time of the sintering temperature is shorter than 2 hours, sintering may not be sufficiently performed, the sintered body density may not be sufficiently high, or the sintered body may be warped. Even if the holding time exceeds 100 hours, there is a waste of unnecessary energy or time, which is not good in terms of productivity. It is preferably 5 to 2.0 hours.

The environment in the cooling process during cooling is the atmospheric environment or the oxygen environment, which is lower than the highest temperature. The temperature of 100 ° C ± 20 ° C is maintained for about 1 hour, whereby more than 95% of the tin-rich phase is present at the grain boundary three junctions. The solid solution Sn is precipitated during the cooling process, and can be maintained at a temperature of 100 ° C ± 20 ° C, so that more than 95% of the tin oxide-rich phase exists at the grain boundary three junctions. Although it can also keep the holding time for more than 1 hour, it cannot see significant changes. Further, the holding time can be appropriately adjusted by maintaining the temperature and the like, and there is no particular limitation if the desired structure can be obtained.

As for the measurement method of the volume resistivity, for example, the type manufactured by NPS Co., Ltd.: Σ-5+ can be used for measurement. In the measurement, first, four metal probes were placed on the straight line of the sample surface, and a fixed current was passed between the two probes on the outer side, and the potential difference generated between the two inner probes was measured to obtain a resistance. The obtained resistivity can be multiplied by the sample thickness and the correction coefficient RCF (Resistivity Correction Factor) to calculate the volume resistivity (volume resistivity).

The sintered body sintered under such conditions, as described above, can have a high density of the sintered body density of 7.03 g/cm ³ or more, and a volume resistivity of 0.10 to 0.15 mΩ. Cm, improve conductivity. Further, it is possible to produce a target in which the maximum size of the above-mentioned tin-rich phase is 1 μm and suppresses the coarsening of the tin-rich phase.

Moreover, the bending strength of the sintered body of the ITO sputtering target can be made 100 MPa or more, and the strength of the target can be improved.

The surface of the sintered body obtained in this manner was ground, and the side was cut into a size of 127 mm × 508 mm by a diamond cutter.

Next, a back sheet made of oxygen-free copper was placed on a hot plate set at 200 ° C, and indium was used as a solder to be applied to have a thickness of about 0.2 mm. The ITO sintered body was bonded to the back sheet, and left to cool to room temperature.

The target was mounted on a magnetron sputtering device (BSC-7011) manufactured by Synchron Corporation, and the input power was 2.3 W/cm ² for DC power, 0.6 Pa at a gas pressure, and argon (Ar) and oxygen (O _{2 ).} The film has a total gas flow rate of 300 sccm and an oxygen concentration of 0 to 4%.

In particular, when the transparent conductive film of the present invention is produced, it is preferably used in a mixed gas atmosphere of argon and oxygen and having an oxygen concentration of 4% or less, without heating the substrate or holding the substrate at 150 ° C or lower, using the ITO of the present invention described above. The target is sputtered and formed on the substrate. The substrate is not only a glass substrate but also a film substrate such as PET.

The transparent conductive film produced in this manner is a transparent conductive film made of In, Sn, O, and unavoidable impurities, and contains Sn/(In+Sn) in an atomic ratio of 1.8% or more and 3.7% or less (however, Excluding 3.7%) of Sn, the resistivity of the film formed by film formation without heating is 3.0mΩ. Below the cm, a transparent conductive film having a film property of a transmittance of 80% or more at a wavelength of 550 nm.

Further, it is also possible to form a transparent conductive film containing Sn in an atomic ratio of Sn/(In+Sn) of 2.3 to 3.2%, and consisting of In, Sn, O and unavoidable impurities. The transparent conductive film produced in this manner can have a crystallization temperature of 120 ° C or lower.

Next, the terms (definition, test method, etc.) used in the present specification will be explained. First, the observation site of the target is an observation site in which the sintered body is divided into four equal parts, and the center portion of the sintered body which is equally divided into four is two fields of view, and the total of eight fields of view is the observation site. A specific example of the observation site is shown in Fig. 4; The upper left diagram of Fig. 4 shows the case of a round sintered body, the right diagram of Fig. 4 shows the case of a square sintered body, and the lower left diagram of Fig. 4 shows the case of a cylindrical type.

(Method for measuring average crystal grain size of sintered body)

The chord method is used as a measure of the average crystal grain size. The string method draws a straight line from the grain boundary to the grain boundary in any direction on the SEM image of × 2,000 times, and crosses the line by 1 The average of the lengths of the particles is taken as the average crystal grain size. On the SEM image (photograph), draw an arbitrary straight line (from the grain boundary to the grain boundary), count the number of intersections with the grain boundary, and calculate it by the following formula (Formula 1).

(Formula 1) Average crystal grain size = length of straight line / number of intersections

Specifically, in the SEM image of the 8 fields of view, five lines of arbitrary lengths parallel to each other are drawn in each field of view, and the average of the total length of the line and the total number of intersections with the grain boundaries is calculated as the average crystallization. Particle size.

After the sample was mirror-polished, it was etched with aqua regia. The SEM image was taken with FE-EPMA (manufactured by JEOL Ltd., JXA-8500F FE electron probe microanalyzer).

(empty hole area ratio)

The voids were observed using a 2,000-fold SEM image. The pores are approximately circular (including a perfect circle), an elliptical shape, and a strained (distorted circle), and the respective diameters are the largest and the long axis diameter (including the diameter). For the hole area ratio, an SEM image of 8 fields of view of × 2,000 times is used, and the area ratio of the holes is calculated from the histogram after the gray scale and binarization processing in Adobe Photoshop Elements 7.0 (8 fields of view) Average area ratio). After the sample was mirror-polished, it was etched with aqua regia. The SEM image was taken with FE-EPMA (manufactured by JEOL Ltd., JXA-8500F FE electron probe microanalyzer).

(about rich tin oxide phase)

Fig. 1 is an ITO sintered body containing Sn having an atomic ratio of Sn/(In+Sn) of 3.8% by FE-EPMA (manufactured by JEOL Ltd., JXA-8500F FE electron probe microanalyzer) × 2000 times the surface analysis of Sn, the rich tin oxide phase means that the Sn intensity is stronger than that of the other phases (the white portion of the image).

The area ratio of the tin-rich phase is measured by an 8-hole image of a 50 μm×50 μm Sn surface analysis image. The Adobe photoshop Elements 7.0 is used to calculate the tin-rich phase from the histogram after gray scale and binarization. Area ratio (average area ratio of 8 fields of view).

The left side of Fig. 1 shows a graph (image) of the Sn surface analysis result of the ITO sintered body containing Sn in an atomic ratio of Sn/(In+Sn) of 3.8%, and the right side shows a SEM image (image).

The maximum size of the tin-rich phase is the maximum major axis diameter in the field of view of the above image 8 .

(About indium oxide phase)

The phase other than the tin oxide-rich phase as shown by the Sn face analysis of Fig. 1 is defined as an indium oxide phase.

(Note that more than 95% of the rich tin oxide phase is present at the grain boundary three junctions)

Grain boundary three joints: Fig. 2 is an SEM image of an ITO sintered body contained in an atomic ratio of Sn/(In+Sn) of 2.8%, and if the grain boundary is along the line A of Fig. 2, Will become the B of Figure 2. The grain boundary three joints refer to the intersection of the grain boundaries of the three particles as shown in Fig. 2B. Part B of Fig. 2 refers to the portion of the three junctions of the amorphous boundary.

Fig. 2 is a result of analysis of the surface of Sn in the same viewing zone as A of Fig. 2, and the portion enclosed by the dotted line is a tin-rich phase. The C of FIG. 2 is superimposed on A of FIG. 2, and it is confirmed whether the tin-rich phase is located at the grain boundary three junctions, and the number of the tin-rich phase and the number of the tin-rich phase of the three junctions of the grain boundary are confirmed. Whether the ratio is above 95% in all 8 fields of view. D of Fig. 2 is an SEM image in which A of Fig. 2 and C of Fig. 2 are superimposed.

(Sintered body bending strength test method)

The test was carried out in accordance with the three-point bending test of the bending strength of the precision ceramic (JIS R 1601). The number of test pieces was 20, and the numerical values recorded were average values. The device used was a tensile compression tester (SV-201NA-50SL type) of the Honda Plant.

(Arc detection sensitivity)

The number of times of arc (microarc) generation (times) was measured by a μ-Arc monitor (MAM Genesis) manufactured by Landmark Technology. The arc determination criterion is an arc in which the detection voltage is 100 V or more and the energy (sputter voltage at the time of arc discharge × sputtering current × occurrence time) is 20 mJ or less.

(protrusion coverage rate)

Figure 3 is a photograph of the target after 35 hours of continuous sputtering. The white dotted frame is photographed by a digital camera. In Adobe Photoshop Elements 7.0, after grayscale and binarization (refer to Figure 3), the protrusion is calculated from the histogram. The area ratio of the object is the average of the three parts as the protrusion coverage.

Example

The present invention will be described below based on examples and comparative examples, but the examples and comparative examples are not intended to limit the scope of the present invention. That is, variations and other embodiments based on the technical idea of the present invention are of course included in the present invention.

(Example 1)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 5 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner has a sintered body density of 7.070 g/cm ³ , a bending strength of 115 MPa, and a volume resistivity of 0.110 mΩ. Cm, the average crystal grain size is 3.43 μm, the area ratio of the tin-rich phase is 0.45%, the probability of the three-contact of the tin-rich phase is 98%, and the void area is 0.08%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 28 times/24 hours, the protrusion coverage was 1%, which was good.

The results are shown in Table 1.

[Table 1]

(Example 2)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1330 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.100 g/cm ³ , a bending strength of 120 MPa, a volume resistivity of 0.116 mΩ·cm, an average crystal grain size of 3.54 μm, and an area ratio of the tin-rich phase. 0.39%, the existence of the three points of the rich tin oxide phase is 99%, and the void area ratio is 0.07%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 23 times/24 hours, the protrusion coverage was 0.8%, which was good.

In the second embodiment, the sputtering gas is argon at the same DC power density and gas pressure, and the oxygen content is 0, 1, 2, 4%, and the glass substrate (EagleXG) is used at a gas flow rate of 300 sccm. Film formation was carried out by heating to prepare an ITO film of 40 nm.

The membrane was heated in an atmospheric environment for 60 minutes to 50 to 200 ° C using an inert oven oven (model: INL-45-S) to XRD (device model: fully automatic horizontal multi-purpose X-ray winding The laser device SmartLab) measures the presence or absence of crystallization of the film before and after heating. The crystallization temperature was a temperature at which the peak of the In ₂ O ₃ (222) plane was confirmed by XRD measurement.

When the oxygen concentration is 0%, the film resistivity is 2.70mΩ. Cm has a transmittance of 80.5% at a wavelength of 500 nm and a crystallization temperature of 100 °C.

When the oxygen concentration is 1%, the film resistivity is 1.01mΩ. The transmittance of cm at a wavelength of 500 nm was 84.0%, and the crystallization temperature was 100 °C.

When the oxygen concentration is 2%, the film resistivity is 0.59mΩ. The transmittance of cm at a wavelength of 500 nm was 88.1%, and the crystallization temperature was 100 °C.

When the oxygen concentration is 4%, the film resistivity is 0.81mΩ. The transmittance of cm at a wavelength of 500 nm was 87.4%, and the crystallization temperature was 100 °C.

This result is shown in Table 2. Both have achieved good results.

(Example 3)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1450 ° C, and the holding time at the highest sintering temperature was 15 hours. Then, it was kept at 1370 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.105 g/cm ³ , a bending strength of 121 MPa, a volume resistivity of 0.124 mΩ·cm, an average crystal grain size of 3.66 μm, and an area ratio of the tin-rich phase. 0.35%, the existence of the three points of the rich tin oxide phase is 99%, and the void area ratio is 0.05%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 20 times / 24 hours, the protrusion coverage was 0.3%, which was good.

(Example 4)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1430 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1330 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.082 g/cm ³ , a bending strength of 116 MPa, a volume resistivity of 0.118 mΩ·cm, an average crystal grain size of 3.26 μm, and an area ratio of the tin-rich phase. 0.68%, the existence rate of the three junctions of the rich tin oxide phase is 99%, and the void area ratio is 0.10%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 25 times/24 hours, the protrusion coverage was 0.7%, which was good.

(Example 5)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.058 g/cm ³ , a bending strength of 113 MPa, a volume resistivity of 0.121 mΩ·cm, an average crystal grain size of 3.20 μm, and an area ratio of the tin-rich phase. 0.83%, the existence rate of the three junctions of the rich tin oxide phase is 98%, and the void area ratio is 0.15%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 31 times / 24 hours, the protrusion coverage was 1.2%, which was good.

(Example 6)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was 1,350 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1250 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.036 g/cm ³ , a bending strength of 110 MPa, a volume resistivity of 0.129 mΩ·cm, an average crystal grain size of 3.01 μm, and an area ratio of the tin-rich phase. 0.95%, the existence rate of the three junctions of the rich tin oxide phase is 97%, and the void area ratio is 0.23%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 40 times / 24 hours, the protrusion coverage was 1.5%, which was good.

(Example 7)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.074 g/cm ³ , a bending strength of 111 MPa, a volume resistivity of 0.131 mΩ·cm, an average crystal grain size of 3.96 μm, and an area ratio of the tin-rich phase. 0.21%, the existence of the three junctions of the rich tin oxide phase is 99%, and the void area ratio is 0.08%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 31 times / 24 hours, the protrusion coverage was 0.9%, which was good.

In the seventh embodiment, the sputtering gas is argon at the same DC power density and gas pressure, and the oxygen content is 0, 1, 2, 4%, and the glass substrate (EagleXG) is not present under the condition that the gas flow rate is 300 sccm. Film formation was carried out by heating to prepare an ITO film of 40 nm.

The membrane was heated in an atmospheric environment for 60 minutes to 50 to 200 ° C using an oxygen-free oven (model: INL-45-S) to XRD (device model: fully automatic horizontal multi-purpose X-ray diffraction device SmartLab) The measurement confirmed whether or not the film before and after heating was crystallized. The crystallization temperature was a temperature at which the peak of the In ₂ O ₃ (222) plane was confirmed by XRD measurement.

When the oxygen concentration is 0%, the film resistivity is 2.93mΩ. The transmittance of cm at a wavelength of 500 nm was 81.1%, and the crystallization temperature was 80 °C.

When the oxygen concentration is 1%, the film resistivity is 1.33mΩ. The transmittance of cm at a wavelength of 500 nm was 83.2%, and the crystallization temperature was 80 °C.

When the oxygen concentration is 2%, the film resistivity is 0.65mΩ. Cm, the transmittance at a wavelength of 500 nm was 88.7%, and the crystallization temperature was 80 °C.

When the oxygen concentration is 4%, the film resistivity is 0.96mΩ. The transmittance of cm at a wavelength of 500 nm was 86.9%, and the crystallization temperature was 80 °C.

The results are shown in Table 2 in the same manner. Both have achieved good results.

(Example 8)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.045 g/cm ³ , a bending strength of 107 MPa, a volume resistivity of 0.125 mΩ·cm, an average crystal grain size of 3.46 μm, and an area ratio of the tin-rich phase. 0.26%, the existence of the three points of the rich tin oxide phase is 99%, and the void area ratio is 0.11%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 33 times/24 hours, the protrusion coverage was 1.2%, which was good.

(Example 9)

The SnO ₂ powder and the In ₂ O ₃ powder, which were adjusted to have an atomic ratio of Sn/(In+Sn) of 2.1%, were used as a sintering raw material, and were sintered in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.079 g/cm ³ , a bending strength of 113 MPa, a volume resistivity of 0.125 mΩ·cm, an average crystal grain size of 3.55 μm, and an area ratio of the tin-rich phase. 0.18%, the existence rate of the three junctions of the rich tin oxide phase is 99%, and the void area ratio is 0.12%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 30 times / 24 hours, the protrusion coverage was 1.3%, which was good.

(Embodiment 10)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.1% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.050 g/cm ³ , a bending strength of 110 MPa, a volume resistivity of 0.122 mΩ·cm, an average crystal grain size of 2.75 μm, and an area ratio of the tin-rich phase. 0.22%, the existence of the three junctions of the rich tin oxide phase is 99%, and the void area ratio is 0.13%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 31 times / 24 hours, the protrusion coverage was 1.6%, which was good.

(Example 11)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.6% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.088 g/cm ³ , a bending strength of 119 MPa, a volume resistivity of 0.123 mΩ·cm, an average crystal grain size of 2.97 μm, and an area ratio of the tin oxide-rich phase. 0.33%, the existence rate of the three junctions of the rich tin oxide phase is 98%, and the void area ratio is 0.10%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 25 times / 24 hours, the protrusion coverage was 1%, which was good.

(Embodiment 12)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.6% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.071 g/cm ³ , a bending strength of 115 MPa, a volume resistivity of 0.119 mΩ·cm, an average crystal grain size of 2.83 μm, and an area ratio of the tin-rich phase. 0.38%, the existence rate of the three junctions of the rich tin oxide phase is 98%, and the void area ratio is 0.10%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 28 times / 24 hours, the protrusion coverage was 1.1%, which was good.

(Example 13)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 3.0% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.103 g/cm ³ , a bending strength of 126 MPa, a volume resistivity of 0.117 mΩ·cm, an average crystal grain size of 3.67 μm, and an area ratio of the tin-rich phase. 0.41%, the existence of the three points of the rich tin oxide phase is 98%, and the void area ratio is 0.08%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 21 times / 24 hours, the protrusion coverage was 0.9%, which was good.

(Example 14)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 3.0% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.091 g/cm ³ , a bending strength of 121 MPa, a volume resistivity of 0.115 mΩ·cm, an average crystal grain size of 3.49 μm, and an area ratio of the tin-rich phase. 0.46%, the probability of the three junctions of the rich tin oxide phase is 98%, and the void area ratio is 0.09%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 24 times / 24 hours, the protrusion coverage was 0.9%, which was good.

(Example 15)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 3.2% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.109 g/cm ³ , a bending strength of 127 MPa, a volume resistivity of 0.110 mΩ·cm, an average crystal grain size of 3.82 μm, and an area ratio of the tin-rich phase. 0.55%, the existence of the three points of the rich tin oxide phase is 98%, and the void area ratio is 0.07%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 18 times/24 hours, the protrusion coverage was 0.7%, which was good.

In this embodiment 15, the sputtering power is made by the same DC power density and air pressure. Argon, having an oxygen content of 0, 1, 2, and 4%, was formed on a glass substrate (Eagle XG) without heating at a gas flow rate of 300 sccm to prepare a 40 nm ITO film.

The membrane was heated in an atmospheric environment for 60 minutes to 50 to 200 ° C using an oxygen-free oven (model: INL-45-S) to XRD (device model: fully automatic horizontal multi-purpose X-ray diffraction device SmartLab) The measurement confirmed whether or not the film before and after heating was crystallized. The crystallization temperature was a temperature at which the peak of the In ₂ O ₃ (222) plane was confirmed by XRD measurement.

When the oxygen concentration is 0%, the film resistivity is 2.65mΩ. The transmittance of cm at a wavelength of 500 nm was 80.1%, and the crystallization temperature was 110 °C.

When the oxygen concentration is 1%, the film resistivity is 0.97mΩ. Cm, the transmittance at a wavelength of 500 nm was 83.6%, and the crystallization temperature was 110 °C.

When the oxygen concentration is 2%, the film resistivity is 0.60mΩ. Cm, the transmittance at a wavelength of 500 nm was 89.2%, and the crystallization temperature was 110 °C.

When the oxygen concentration is 4%, the film resistivity is 0.84mΩ. Cm, the transmittance at a wavelength of 500 nm was 87.6%, and the crystallization temperature was 110 °C.

The results are shown in Table 2 in the same manner. Both have achieved good results.

(Embodiment 16)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 3.2% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.100 g/cm ³ , a bending strength of 123 MPa, a volume resistivity of 0.104 mΩ·cm, an average crystal grain size of 3.77 μm, and an area ratio of the tin-rich phase. 0.62%, the existence of the three points of the rich tin oxide phase is 98%, and the void area ratio is 0.06%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 18 times/24 hours, the protrusion coverage was 0.6%, which was good.

(Example 17)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 3.5% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.112 g/cm ³ , a bending strength of 130 MPa, a volume resistivity of 0.111 mΩ·cm, an average crystal grain size of 4.02 μm, and an area ratio of the tin-rich phase. 0.62%, the existence of the three points of the rich tin oxide phase is 98%, and the void area ratio is 0.06%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 15 times / 24 hours, the protrusion coverage was 0.6%, which was good.

(Embodiment 18)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 3.5% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.102 g/cm ³ , a bending strength of 128 MPa, a volume resistivity of 0.106 mΩ·cm, an average crystal grain size of 3.89 μm, and an area ratio of the tin-rich phase. 0.70%, the existence of the three points of the rich tin oxide phase is 97%, and the void area ratio is 0.05%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 14 times/24 hours, the protrusion coverage was 0.5%, which was good.

(Comparative Example 1)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was set to 1550 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1450 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.112 g/cm ³ , a bending strength of 122 MPa, a volume resistivity of 0.135 mΩ·cm, an average crystal grain size of 7.64 μm, and an area ratio of the tin-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 0.52%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 120 times/24 hours, the protrusion coverage rate was 2.5%, which did not satisfy the conditions of the present invention and was poor.

(Comparative Example 2)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was set to 1500 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1400 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.106 g/cm ³ , a bending strength of 120 MPa, a volume resistivity of 0.124 mΩ·cm, an average crystal grain size of 5.98 μm, and an area ratio of the tin-rich phase. 0.02%, the existence of the three points of the rich tin oxide phase is 99%, and the void area ratio is 0.68%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 148 times/24 hours, the protrusion coverage rate was 3.1%, which did not satisfy the conditions of the invention of the present invention and was poor.

(Comparative Example 3)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 1 hour. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 6.989 g/cm ³ , a bending strength of 103 MPa, a volume resistivity of 0.121 mΩ·cm, an average crystal grain size of 3.25 μm, and an area ratio of the tin-rich phase. 0.58%, the existence rate of the three junctions of the rich tin oxide phase is 94%, and the void area ratio is 0.20%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 334 times/24 hours, the protrusion coverage rate was 4.8%, which did not satisfy the conditions of the invention of the present invention and was poor.

(Comparative Example 4)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was set to 1550 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1450 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.098 g/cm ³ , a bending strength of 115 MPa, a volume resistivity of 0.125 mΩ·cm, an average crystal grain size of 6.21 μm, and an area ratio of the tin oxide-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 0.55%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 100 times/24 hours, the protrusion coverage rate was 2.6%, which did not satisfy the conditions of the present invention and was poor.

(Comparative Example 5)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was set to 1500 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1400 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.066 g/cm ³ , a bending strength of 111 MPa, a volume resistivity of 0.120 mΩ·cm, an average crystal grain size of 5.12 μm, and an area ratio of the tin oxide-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 0.63%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 114 times/24 hours, the protrusion coverage rate was 2.9%, which did not satisfy the conditions of the present invention and was poor.

(Comparative Example 6)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.6% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.048 g/cm ³ , a bending strength of 103 MPa, a volume resistivity of 0.133 mΩ·cm, an average crystal grain size of 4.05 μm, and an area ratio of the tin-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 0.62%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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. The ratio of the protrusion coverage was 2.9% for 128 times/24 hours, which did not satisfy the conditions of the invention of the present invention.

(Comparative Example 7)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.6% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.024 g/cm ³ , a bending strength of 98 MPa, a volume resistivity of 0.138 mΩ·cm, an average crystal grain size of 3.83 μm, and an area ratio of the tin-rich phase. 0.02%, the existence of the three points of the rich tin oxide phase is 99%, and the void area ratio is 0.66%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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. The 145 times/2.4 hours, the protrusion coverage rate was 3.3%, which did not satisfy the conditions of the invention of the present invention, and was bad.

(Comparative Example 8)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.4% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.030 g/cm ³ , a bending strength of 99 MPa, a volume resistivity of 0.139 mΩ·cm, an average crystal grain size of 4.68 μm, and an area ratio of the tin oxide-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 0.78%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 138 times/24 hours, the protrusion coverage rate was 3.2%, which did not satisfy the conditions of the invention of the present invention and was poor.

In Comparative Example 8, the sputtering gas was argon at the same DC power density and gas pressure, and the oxygen content was 0, 1, 2, 4%, and the glass substrate (Eagle XG) was used at a gas flow rate of 300 sccm. Film formation was carried out by heating to prepare an ITO film of 40 nm.

The membrane was heated in an atmospheric environment for 60 minutes to 50 to 200 ° C using an oxygen-free oven (model: INL-45-S) to XRD (device model: fully automatic horizontal multi-purpose X-ray diffraction device SmartLab) The measurement confirmed whether or not the film before and after heating was crystallized. The crystallization temperature was a temperature at which the peak of the In ₂ O ₃ (222) plane was confirmed by XRD measurement.

When the oxygen concentration is 0%, the film resistivity is 6.21mΩ. Cm, the transmittance at a wavelength of 500 nm was 72.9%, and the crystallization temperature was 50 °C.

When the oxygen concentration is 1%, the film resistivity is 4.60mΩ. Cm, at a wavelength of 500nm The incident rate was 76.3%, and the crystallization temperature was 50 °C.

When the oxygen concentration is 2%, the film resistivity is 3.01mΩ. Cm, the transmittance at a wavelength of 500 nm was 78.7%, and the crystallization temperature was 50 °C.

When the oxygen concentration is 4%, the film resistivity is 4.38mΩ. Cm, the transmittance at a wavelength of 500 nm was 75.4%, and the crystallization temperature was 50 °C.

The results are shown in Table 2 in the same manner. None of the conditions of the present invention were met, which was bad.

(Comparative Example 9)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 1.4% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.015 g/cm ³ , a bending strength of 90 MPa, a volume resistivity of 0.145 mΩ·cm, an average crystal grain size of 4.07 μm, and an area ratio of the tin-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 0.85%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 162 times/24 hours, the protrusion coverage rate was 3.5%, which did not satisfy the conditions of the invention of the present invention and was poor.

(Comparative Example 10)

The SnO ₂ powder and the In ₂ O ₃ powder, which were adjusted to have an atomic ratio of Sn/(In+Sn) of 1.2%, were used as a sintering raw material, and were sintered in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.009 g/cm ³ , a bending strength of 88 MPa, a volume resistivity of 0.148 mΩ·cm, an average crystal grain size of 5.03 μm, and an area ratio of the tin oxide-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 0.88%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 173 times/24 hours, the protrusion coverage rate was 3.8%, which did not satisfy the conditions of the invention of the present invention and was poor.

(Comparative Example 11)

The SnO ₂ powder and the In ₂ O ₃ powder, which were adjusted to have an atomic ratio of Sn/(In+Sn) of 1.2%, were used as a sintering raw material, and were sintered in an oxygen atmosphere. The highest sintering temperature was 1400 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1300 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 6.994 g/cm ³ , a bending strength of 80 MPa, a volume resistivity of 0.156 mΩ·cm, an average crystal grain size of 4.54 μm, and an area ratio of the tin-rich phase. 0.00%, the existence of the three points of the rich tin oxide phase is 0%, and the void area ratio is 1.02%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 199 times/24 hours, the protrusion coverage rate was 1.3%, which did not satisfy the conditions of the invention of the present invention and was poor.

(Comparative Example 12)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 3.7% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1350 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.112 g/cm ³ , a bending strength of 120 MPa, a volume resistivity of 0.120 mΩ·cm, an average crystal grain size of 4.32 μm, and an area ratio of the tin oxide-rich phase. 2.3%, the existence of the three points of the rich tin oxide phase is 92%, and the void area ratio is 0.22%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 60 times/24 hours, the protrusion coverage rate was 1.3%, which did not satisfy the conditions of the invention of the present invention and was poor.

In Comparative Example 12, the sputtering gas was argon at the same DC power density and gas pressure, and the oxygen content was 0, 1, 2, 4%, and the glass substrate (Eagle XG) was used at a gas flow rate of 300 sccm. Film formation was carried out by heating to prepare an ITO film of 40 nm.

The membrane was heated in an atmospheric environment for 60 minutes to 50 to 200 ° C using an oxygen-free oven (model: INL-45-S) to XRD (device model: fully automatic horizontal multi-purpose X-ray diffraction device SmartLab) The measurement confirmed whether or not the film before and after heating was crystallized. The crystallization temperature was a temperature at which the peak of the In ₂ O ₃ (222) plane was confirmed by XRD measurement.

When the oxygen concentration is 0%, the film resistivity is 2.74mΩ. Cm, the transmittance at a wavelength of 500 nm was 77.1%, and the crystallization temperature was 130 °C.

When the oxygen concentration is 1%, the film resistivity is 0.99mΩ. Cm, the transmittance at a wavelength of 500 nm was 84.6%, and the crystallization temperature was 130 °C.

When the oxygen concentration is 2%, the film resistivity is 0.61mΩ. Cm, at a wavelength of 500nm The rate of incidence was 86.8% and the crystallization temperature was 130 °C.

When the oxygen concentration is 4%, the film resistivity is 0.87mΩ. Cm, the transmittance at a wavelength of 500 nm was 85.1%, and the crystallization temperature was 130 °C.

The results are shown in Table 2 in the same manner. None of the conditions of the present invention were met, which was bad.

(Comparative Example 13)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, the cooling is not maintained at a specific temperature. The sintered body obtained in the above manner had a sintered body density of 7.093 g/cm ³ , a bending strength of 110 MPa, a volume resistivity of 0.110 mΩ·cm, an average crystal grain size of 3.55 μm, and an area ratio of the tin-rich phase. 0.10%, the existence of the three points of the rich tin oxide phase is 91%, and the pore area ratio is 0.07%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 156 times/24 hours, the protrusion coverage rate was 2.0%, which did not satisfy the conditions of the present invention and was poor.

(Comparative Example 14)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1250 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.095 g/cm ³ , a bending strength of 115 MPa, a volume resistivity of 0.123 mΩ·cm, an average crystal grain size of 3.58 μm, and an area ratio of the tin-rich phase. 0.08%, the existence rate of the three junctions of the rich tin oxide phase was 92%, and the void area ratio was 0.06%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 140 times/24 hours, the protrusion coverage rate was 2.2%, which did not satisfy the conditions of the invention of the present invention and was poor.

(Comparative Example 15)

The use ratio was adjusted so that SnO ₂ powder and In ₂ O ₃ powder having an atomic ratio of Sn/(In+Sn) of 2.8% were used as sintering raw materials, and sintering was performed in an oxygen atmosphere. The maximum sintering temperature was set to 1450 ° C, and the holding time at the highest sintering temperature was 10 hours. Then, it was kept at 1400 ° C for 1 hour while cooling down. The sintered body obtained in the above manner had a sintered body density of 7.100 g/cm ³ , a bending strength of 120 MPa, a volume resistivity of 0.136 mΩ·cm, an average crystal grain size of 3.65 μm, and an area ratio of the tin-rich phase. 0.05%, the existence of the three junctions of the rich tin oxide phase is 90%, and the void area ratio is 0.07%.

The target was produced using this sintered body, and the sputtering was continuously performed for 35 hours under conditions of 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 230 times/24 hours, the protrusion coverage rate was 2.6%, which did not satisfy the conditions of the invention of the present invention and was poor.

The film resistivity, the transmittance at a wavelength of 500 nm, and the crystallization temperature in the case of changing the oxygen concentration in the case of performing sputtering in the above-described examples and comparative examples are described with reference to Example 2, Example 7, and Example. 15. Comparative Example 8 and Comparative Example 12, and other examples and comparative examples are omitted. However, in order to avoid complication, the same results can be obtained.

The present invention relates to an ITO sputtering target which is suitable for forming a transparent conductive film and which can form a low-resistance film of a low-resistance film even at a low temperature, and can provide a target having a small particle size, high density, high strength, and reduction of arc or The ITO sputtering target of the protrusions.

Moreover, the film characteristics can be reduced as the sputtering progresses, and the quality of the film formation can be improved. As a result, it has an excellent effect of improving the productivity and reliability of the ITO target. The ITO sputtering target of the present invention is particularly useful for forming an ITO film, and is most suitable for use in touch panels, flat panel displays, organic ELs, solar cells, and the like.

Claims (10)

A sputtering target is a sintered body composed of In, Sn, O, and unavoidable impurities, and contains Sn/(In+Sn) in an atomic ratio of 1.8% or more and 3.7% or less (except for 3.7%). Sn, the average crystal grain size of the sintered body is in the range of 1.0 to 5.0 μm, and the pores having a major axis diameter of 0.1 to 1.0 μm are an area ratio of 0.5% or less, which is a phase of the indium oxide phase and the tin-rich phase, and is rich in tin oxide. The area ratio of the phase is below 0.1 to 1.0%, and more than 95% of the rich tin oxide phase exists at the grain boundary three junctions. A sputtering target according to the first aspect of the patent application, which contains Sn in an atomic ratio of Sn/(In+Sn) of 2.3 to 3.2%. For example, the sputtering target of the first application of the patent scope has a sintered body density of 7.03 g/cm ³ or more and a volume resistivity of 0.10 to 0.15 mΩ. Cm. For example, the sputtering target of the second application of the patent scope has a sintered body density of 7.03 g/cm ³ or more and a volume resistivity of 0.10 to 0.15 mΩ. Cm. The sputtering target according to any one of claims 1 to 4, wherein the maximum size of the tin-rich phase is 1 μm or less. The sputtering target according to any one of claims 1 to 4, which has a bending strength of 100 MPa or more. The sputtering target of the fifth application of the patent application has a bending strength of 100 MPa or more. A method for producing an ITO sputtering target, which is a method for producing a sputtering target composed of In, Sn, O and unavoidable impurities according to any one of claims 1 to 7, wherein SnO ₂ powder and In _{2 are used} The O ₃ powder is adjusted in such a manner that the atomic ratio of Sn/(In+Sn) is 1.8% or more and 3.7% (except for 3.7%), and the mixture is mixed, and the maximum sintering temperature is maintained at 1,450 ° C under an oxygen atmosphere. The sintering is carried out at the following temperature, and is maintained at a temperature lower than the sintering holding temperature of 100 ° C ± 20 ° C in the cooling step after sintering. The method for producing a sputtering target according to the eighth aspect of the invention, wherein the SnO ₂ powder and the In ₂ O ₃ powder are adjusted in a ratio of 2.3 to 3.2% by atomic ratio of Sn/(In+Sn). Mix and then sinter. A method for producing a transparent conductive film, which is a method for producing a transparent conductive film by sputtering, characterized in that in a mixed gas atmosphere composed of argon and oxygen and having an oxygen concentration of 4% or less, the substrate is not heated or the substrate is held A sputtering target of any one of claims 1 to 7 is formed on the substrate at 150 ° C or lower.