TWI660056B - Ito sputtering target material and method for producing the same - Google Patents

Abstract

The ITO sputtering target of the present invention has a content of Sn of 2.8 to 3.5% by mass in terms of SnO _2. Among them, there are _two phases of a phase in which SnO ₂ is solid-dissolved in In ₂ O ₃ and a phase of In ₄ Sn ₃ O ₁₂ . The relative density is above 98%, and the length of change due to strain relaxation is 50 μm or less per 1 m. The ITO sputtering target of the present invention has a composition in which the content of Sn is 2.8 to 3.5% by mass in terms of SnO _{2 and} is easily cracked, but it is difficult to crack during bonding, and the occurrence of small particles in sputtering is small. Therefore, an ITO thin film can be efficiently formed.

Description

ITO sputtering target and manufacturing method thereof

The present invention relates to an ITO sputtering target, and more specifically, it relates to an ITO sputtering target that is hard to produce cracks during bonding and can be efficiently formed into a film.

ITO (Indium-Tin-Oxide) film is widely used in transparent electrodes and touch panels of flat displays because of its high light transmission and electrical conductivity. The ITO film for transparent electrodes usually contains about 10% by mass of Sn in terms of SnO ₂ conversion. However, the ITO film used in touch panels is based on the relationship with the heat treatment of the film. The Sn content is 2.5 to 8.0 in terms of SnO ₂ conversion. About mass%.

The ITO film is generally formed by sputtering of an ITO sputtering target. The ITO sputtering target is generally used in combination with a support plate made of Cu. Therefore, when forming an ITO film for a touch panel, generally, an ITO sputtering target with an Sn content that can achieve the intended film resistance is combined with a Cu support plate to perform sputtering.

However, it is known that an ITO sputtering target having a content of Sn of less than 10% by mass in terms of SnO ₂ is fragile and easily cracked. In particular, when the content of Sn is 3.5% by mass or less in terms of SnO ₂ , the tendency to crack easily becomes significant, which becomes a great obstacle in the production of targets. It is known that among these ITO sputtering targets, the reason for the remaining residual stress during firing in the manufacturing process is that the target has low strength. Therefore, when these ITO sputtering targets are bonded to a support plate made of Cu or the like, cracks easily occur.

Furthermore, when sputtering an ITO sputtering target whose content of Sn is less than 10% by mass in terms of SnO ₂ , it is also one of the problems to suppress the occurrence of small particles. The occurrence of this nodule can be improved by increasing the density of the target. However, when the density of the target material is increased, the residual stress becomes large and a problem of easy cracking occurs.

In addition, when the firing temperature is lowered and the firing density is as low as 97%, an ITO target having a small residual stress, hard to crack, and a small crystal structure can be obtained. However, pinholes increase in the target, which is the reason. In addition, there is a problem that the number of small particles increases during sputtering. That is, there is a relationship between making it difficult for the ITO target to crack and suppressing nodule systems.

Japanese Patent Application Laid-Open No. 10-147862 relates to an indium oxide / tin oxide sintered body having a small tin content of 3 to 12% by weight, and describes the average particle size of crystals or the maximum agglomeration diameter of tin atoms. Nothing was said about the target's cracked wire.

Further, Japanese Patent Application Laid-Open No. 2010-255022 describes that the crystalline phase of the sintered body is a single phase in an ITO sintered body in which the content of tin oxide relative to indium oxide is 1.5% to 3.5% by mass, and The relationship between the average crystal grain size and the bending strength (70 MPa or more) of the sintered body. However, the ITO target made of the sintered body has insufficient suppression of cracking.

[Prior technical literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 10-147862

[Patent Document 2] Japanese Patent Laid-Open No. 2010-255022

An object of the present invention is to provide an ITO sputtering target material, which is contained in an ITO sputtering target material having a Sn content of 2.8 to 3.5% by mass in terms of SnO ₂ conversion. The occurrence of small nodules is small.

In order to achieve the foregoing object, the present inventors have conducted intensive research and found that an ITO sputtering target has a Sn content of 2.8 to 3.5% by mass in terms of SnO ₂ conversion. Among them, the target has an In ₂ O _{3 content.} The solid solution contains _two phases of the SnO ₂ phase and the In ₄ Sn ₃ O ₁₂ phase. The relative density of the target is more than 98%. When the length of the change caused by the strain relaxation of the target is 50 μm or less per 1 m, the foregoing can be achieved. purpose. Furthermore, in order to obtain such physical properties, it was found that it was necessary to cool the formed body at 60 ° C / hr or less after firing.

That is, the ITO sputtering target of the present invention has a Sn content of 2.8 to 3.5% by mass in terms of SnO ₂ , and includes a phase in which SnO ₂ is solid-dissolved in In ₂ O ₃ and an In ₄ Sn ₃ O ₁₂ phase. The second phase has a relative density of 98% or more, and the length of the change due to strain relaxation is 50 μm or less per 1 m.

The ITO sputtering target is preferably a variation length of 1 μm or less due to strain relaxation.

The bending strength of the ITO sputtering target system is preferably 13.0 kgf / mm ² or more, and more preferably 14.0 kgf / mm ² or more.

Another invention is a method for manufacturing the above-mentioned ITO sputtering target material, comprising the following steps: a shaped body made of a raw material for ITO manufacturing containing an SnO ₂ raw material powder having an average particle size of 0.5 μm or more is fired in a furnace at 1500 to It is fired at a firing temperature of 1600 ° C. The temperature in the firing furnace reaches a temperature range from 700 to 1100 ° C, so that the temperature in the firing furnace is reduced at a temperature lower than 60 ° C / hr. This cooled the fired body obtained.

The ITO sputtering target material of the present invention has a composition in which the content of Sn is 2.8 to 3.5% by mass in terms of SnO ₂ and is extremely prone to cracking. At the same time, it is difficult to crack when combined, and the generation of small particles in sputtering is small. Therefore, an ITO thin film can be efficiently formed. The manufacturing method of the ITO sputtering target material of this invention can manufacture the said target material very efficiently.

1‧‧‧ strain gauge

2‧‧‧ Wiring

3‧‧‧ Target fragment

Fig. 1 is an explanatory diagram of a method for measuring a change length due to strain relaxation.

The ITO sputtering target of the present invention (hereinafter, also referred to as an ITO target) is an ITO target having a Sn content of 2.8 to 3.5% by mass in terms of SnO ₂ conversion, and has SnO dissolved in Inn ₂ O _{3 The two} phases and the _two phases of In ₄ Sn ₃ O ₁₂ phase have a relative density of 98% or more, and the length of change due to strain relaxation is 50 μm or less per 1 m. The ITO sputtering target of the present invention is difficult to crack when combined, and the generation of small particles in sputtering is very small.

As described above, the conventional ITO target material whose content of Sn is 2.8 to 3.5% by mass in terms of SnO ₂ is prone to cause residual stress and low strength, and is therefore fragile and easily cracked. When the ITO target is manufactured, if the firing temperature is lowered and the relative density of the target is set to 97% or less, the residual stress will be reduced and cracking will not be easy, but small particles will be increased during sputtering. When the relative density of the ITO target is set to 98% or more, the number of small particles at the time of sputtering is reduced, but the residual stress is increased or cracked easily. That is, in the conventional ITO target in which the content of Sn is 2.8 to 3.5% by mass in terms of SnO ₂ , it is impossible to coexist with difficulty in cracking and suppression of small particles.

The present invention succeeds in coexisting the difficulty of cracking and the suppression of small nodule in an ITO target having a Sn content of 2.8 to 3.5% by mass in terms of SnO ₂ conversion. The coexistence of cracking difficulty and suppression of small nodule is the first time that the ITO target has a phase in which SnO ₂ is solid-dissolved in In ₂ O ₃ , and the content of Sn is higher than that in which SnO ₂ is solid-dissolved in In ₂ O ₃ . More phases of In ₄ Sn ₃ O ₁₂ phase can be realized by two phases.

The manufacturing of ITO is generally performed by making a molded body from a mixed powder of In ₂ O ₃ powder and SnO ₂ powder, and firing the molded body. During this firing, SnO ₂ will gradually dissolve in In ₂ O ₃ . In this case, for example, the content of Sn in terms of SnO ₂ to 10% of the ITO, SnO ₂ is not completely dissolved in the In ₂ O _3, In ₂ O ₃ it is in a solid solution phases other than the mother phase of SnO ₂ of In ₄ Sn ₃ O ₁₂ phase can be formed as a phase rich in Sn. As a result, the ITO system having a SnO ₂ content of 10% in terms of SnO _{2 had two} phases, a mother phase and an In ₄ Sn ₃ O ₁₂ phase. On the other hand, in conventional ITO in which the content of Sn is 2.8 to 3.5% by mass in terms of SnO ₂ , the amount of Sn is small, and SnO ₂ can be completely dissolved in In ₂ O ₃ , so In ₄ Sn ₃ is not formed. O ₁₂ phase. As a result, SnO ₂ content of SnO ₂ in terms of 2.8 to 3.5 mass% of the conventional ITO, Department of In ₂ O ₃ since only the single phase solid solution of SnO ₂ phase composed of.

The present invention is based by a manufacturing method described later after use, the content of SnO ₂ to SnO ₂ of 2.8 to 3.5 in terms of% by mass, while in the In ₂ O ₃ having a solid solution of SnO ₂ and Phase In ₄ Sn ₃ O ₁₂ Two phases, and a relative density of 98% or more, successfully produced an ITO target with a variation in length of 1 μm or less due to strain relaxation, which is an indicator of residual stress. As a result, in an ITO target having a SnO ₂ content of 2.8 to 3.5% by mass, it is possible to coexist with difficulty in cracking and suppression of small nodules.

An ITO target having a SnO ₂ content of 2.8 to 3.5% by mass is set to have a structure having _two phases of a phase in which SnO ₂ is solid-solved in In ₂ O ₃ and a phase of In ₄ Sn ₃ O ₁₂ . The reason for the difficulty of cracking and the coexistence of small nodules is not necessarily clear, but in this structure, the In ₄ Sn ₃ O ₁₂ phase can be considered to exist in the grain boundary of the phase in which SnO ₂ is solid-dissolved in In ₂ O ₃ , so it is not It is caused by the wedge action of the mutual combination of the SnO ₂ phase in which the In ₂ O _{3 is} dissolved. As a result, Xian believes that the aforementioned two-phase ITO target material can achieve small particle size suppression by increasing its density. On the other hand, even if residual stress occurs, if it is less than a certain value, it is not unavailable. Hard to crack. For example, ITO with Sn content of 10% in terms of SnO ₂ is generally more difficult to crack than ITO with SnO ₂ content of 2.8 to 3.5% by mass. The former ITO is as described above. In ₂ O ₃ The solid solution is composed of two phases of the SnO ₂ phase and the In ₄ Sn ₃ O ₁₂ phase, and the In ₄ Sn ₃ O ₁₂ phase exerts the effect as described above.

The content of Sn in the ITO target material of the present invention is 2.8 to 3.5% by mass in terms of SnO ₂ conversion. The specific Sn content is determined from the aforementioned range based on the physical properties required for the film obtained from the target.

The relative density of the ITO target material of the present invention is more than 98%, more preferably more than 98.5%, and even more preferably more than 99.0%. When the relative density is 98% or more, the occurrence of small particles can be suppressed during sputtering, and good sputtering can be performed.

The change length of the ITO target of the present invention due to strain relaxation is preferably 50 μm or less per 1 m, and preferably 40 μm or less per 1 m. The change in length due to strain relaxation refers to the difference between the length of the ITO target before it is released and the length of the ITO target after it is released when substantially all the residual stress of the ITO target is released. The length of change due to strain relaxation is a physical property value that is an index of residual stress. The length of change due to strain relaxation can be measured using a strain gauge. The method for measuring the change length of the ITO target due to strain relaxation is described in detail in the examples. The ITO target material of the present invention has the _two phases of a phase in which SnO ₂ and In ₄ Sn ₃ O ₁₂ are solid-dissolved in In ₂ O ₃ as described above, so even if there is residual stress, it is not easy to crack, but there is a cause When the variation in length caused by strain relaxation is a large residual stress exceeding 50 μm per 1 m, the probability of cracking in the subsequent processing or bonding steps becomes higher.

The ITO target of the present invention preferably has a flexural strength of 13.0 kgf / mm ² or more, and more preferably 14.0 kgf / mm ² or more. When the ITO target of the present invention satisfies this condition, the occurrence of cracks can be prevented more effectively.

The shape and size of the ITO target material of the present invention are not particularly limited. Even if the ITO target material of any shape and size meets the above conditions, it can achieve the purpose of the present invention. Examples of the shape system include a flat plate shape and a cylindrical shape.

Hereinafter, the manufacturing method of the ITO target of this invention is explained in full detail.

The manufacturing method of the ITO target material of the present invention includes the following steps: firing a shaped body made from a raw material for ITO manufacturing containing a SnO ₂ raw material powder having an average particle diameter of 0.5 μm or more, at a temperature ranging from 1500 to 1600 ° C., The fired body obtained is further cooled at a temperature lowering rate of 60 ° C / hr or less. By this manufacturing method, the above-mentioned ITO target can be manufactured.

The raw materials for ITO production include SnO ₂ powder, and usually contain In ₂ O ₃ powder and SnO ₂ powder. The In ₂ O ₃ powder and the SnO ₂ powder of the raw material powder were mixed so that the content of the SnO ₂ powder became 2.8 to 3.5% by mass, to prepare a mixed powder. The particles of each raw material powder are usually aggregated. Therefore, it is preferable to pulverize and mix beforehand, or pulverize while mixing.

The average particle diameter of the In ₂ O ₃ powder is usually 0.2 to 1.5 μm, preferably 0.4 to 1.0 μm. The average particle diameter of the SnO ₂ powder is 0.5 μm or more, preferably 0.5 μm to 5.0 μm, and more preferably 0.6 μm to 2.0 μm. In the manufacturing method of the ITO target material of the present invention, in order to obtain an ITO target material having a _two- phase phase of SnO ₂ solid solution in In ₂ O _{3 and} a phase of In ₄ Sn ₃ O ₁₂ phase, the average particle diameter of the SnO ₂ powder must be 0.5 μm or more. If the average particle diameter of the SnO ₂ powder is 0.5 μm or more, an In ₄ Sn ₃ O ₁₂ phase with a Sn-rich phase is formed during firing. It is considered that when the average particle diameter of this series of SnO ₂ powder is 0.5 μm or more, during the firing of the aforementioned compact, SnO _{2 is} not completely solid-solved in In ₂ O ₃ , and the incompletely-solubilized SnO ₂ forms In ₄ Sn ₃ O ₁₂ phase. On the other hand, if the average particle diameter of the SnO ₂ powder is less than 0.5 μm, the In ₄ Sn ₃ O ₁₂ phase is not formed. It is considered that when the average particle diameter of this series of SnO ₂ powder is less than 0.5 μm, SnO _{2 is} easily solid-solved in In ₂ O ₃ during the firing of the aforementioned shaped body, and at least most of SnO ₂ is solid-dissolved in In ₂ O ₃ reasons. Therefore, it is necessary to intend to use SnO ₂ powder having a large average particle diameter of 0.5 μm or more. The average particle diameter is a volume cumulative particle diameter D50 of a cumulative volume of 50% by volume obtained by a laser diffraction scattering particle size distribution measurement method.

There is no particular limitation on the method for pulverizing or mixing the raw material powder. For example, the raw material powder can be placed in a bowl and pulverized or mixed by a ball mill.

The mixed powder can also be directly shaped into a shaped body and then sintered, but if necessary, a binder can be added to the mixed powder to form a shaped body. The binder can be a binder used when a molded body is obtained by a known powder metallurgy method, such as polyvinyl alcohol, an acrylic emulsion binder, and the like. In addition, the obtained forming system may be degreased by a method adopted in a known powder metallurgy method as required. The forming method can also be used in a known powder metallurgy method, for example, it is suitable for casting. The density of the formed body is usually 50 to 75%.

The obtained formed body is fired to be a fired body, and then cooled to obtain a sintered body. The firing furnace used for firing is not limited as long as it can control the cooling rate during cooling, and can be generally used for powder Metallurgical firing furnace. The firing environment is suitable for oxygen environment.

The temperature increase rate is usually from 100 to 500 ° C./hour from the viewpoint of high density and crack prevention. The firing temperature is 1500 to 1600 ° C, preferably 1520 to 1580 ° C. If the firing temperature is within the aforementioned range, a high-density sintered body can be obtained. The holding time at the aforementioned firing temperature is usually 3 to 30 hours, preferably 5 to 20 hours. When the retention time is within the aforementioned range, a high-density sintered body is easily obtained.

After the firing is completed, the temperature in the firing furnace ranges from the aforementioned firing temperature to 700 to 1100 ° C, for example, to 800 ° C. The temperature in the firing furnace is preferably 60 ° C / hr or less. The resulting fired body is cooled at a temperature of 30 ° C./hr or lower. Cooling at a temperature lowering speed within this range can reduce the length of the sintered body due to strain relaxation, and can be set to 50 μm or less per 1 m. The temperature decrease rate in the subsequent firing furnace is not particularly limited as long as it can prevent cracking and the like of the fired body. For example, it can be set to 50 to 150 ° C / hr.

The ITO sintered body obtained in this way is cut into a desired shape as needed, and the ITO target of the present invention is obtained by grinding or the like.

The ITO target of the present invention is usually used in combination with a support plate. The support plate is usually made of Cu, Al, Ti or stainless steel. The bonding material may be a bonding material used for bonding conventional ITO targets, for example, In metal. The bonding method is the same as that of the conventional ITO target. For example, the ITO target material and the support plate of the present invention are heated to a temperature at which the bonding material will melt, for example, about 200 ° C, the bonding material is coated on the respective bonding surfaces of the target material and the support plate, and the bonding surfaces are bonded and pressed. After connecting both, cool down. Or, in The respective bonding surfaces of the ITO target material and the support plate of the present invention are coated with bonding materials and bonded to the respective bonding surfaces, and the target material and the support plate are heated to a temperature at which the bonding agent will melt, for example, about 200 ° C. cool down.

[Example]

The evaluation methods of the ITO targets obtained in the following examples and comparative examples are shown below.

Relative density

The relative density of the ITO target was measured according to the Archimedes method. Specifically, the air weight of the target is divided by the volume (weight of water in the target / water specific gravity at the measurement temperature), and the percentage of the theoretical density ρ (g / cm ³ ) based on the following formula (X) The value is set to the relative density (unit:%).

ρ = ((C1 / 100) / ρ 1+ (C2 / 100) / ρ 2 + ‧‧‧ + (Ci / 100) / ρ i) ^-1 (X)

(In the formula, C1 to Ci represent the content (% by weight) of the constituent material of the target, and ρ 1 to ρ i represent the density (g / cm ³ ) of each constituent material corresponding to C1 to Ci.)

2. Average particle size of raw material powder

The average particle diameter of the raw material powder was measured using a laser diffraction scattering particle size distribution measuring device (HRA 9320-X100) manufactured by Nikkiso Co., Ltd. The solvent was measured with water using a refractive index of 2.20 of the measurement substance.

3. Determination of flexural strength

The flexural strength is measured in accordance with JIS-R-1601.

4.Specification of target structure (crystalline phase)

Observe the phase of SnO ₂ solid solution in In ₂ O ₃ by electron microscope observation. The specificity of the In ₄ Sn ₃ O ₁₂ phase was determined by investigating the distribution of Sn by Auger electron spectrometry.

It was confirmed that the phase in which SnO ₂ was solid-dissolved in In ₂ O ₃ and the phase of In ₄ Sn ₃ O ₁₂ were evaluated as "two-phase". Only the phase in which SnO ₂ was solid-dissolved in In ₂ O ₃ was confirmed. Evaluated as "single phase".

5. Change length of target due to strain relaxation (1 gauge method 2-line type)

Apply a special adhesive on the cleaned target surface with a special adhesive (N 11-FA-2-120-VSE 1, nominal resistance 120Ω, gauge rate 2.0 / manufactured by Avionics, Japan), diamond sawtooth machine Cut the target. As shown in FIG. 1, the cutting is performed with the strain gauge 1 on which the wiring 2 is installed as the center and parallel to the four sides of the strain gauge 1 to obtain a target piece 3 with a size of 20 × 20 mm. The change in the length of the target caused by the strain-releasing strain of the target was measured by a data logger (remote scanner DC6100 / manufactured by Avionics, Japan) connected to wiring 2. The measurement was performed at room temperature (25 ° C).

6. Cracking of the target during bonding

In order to bond the target, a flat support plate made of Cu having a sufficient area is bonded to the target by the following method. The target material and the support plate are heated to 160 ° C., and In solder is coated on the respective bonding surfaces of the target material and the base material as bonding materials, and the respective bonding surfaces are bonded to each other, and then the two are pressed and then cooled. Visually observe the target for cracks during bonding. When the crack was confirmed, it was evaluated as "yes", but not confirmed Time evaluation is "none".

7. Evaluation of the amount of small particles

The ITO target without cracking during the bonding was cut with a wire cutter to a size for evaluation of small particles, and was sputtered under the following conditions. The surface of the target after sputtering was photographed, and the area of the small grains was determined from the obtained image by photography using an image analysis software (particle analysis version 3 Nippon Steel & Sumikin Technology Co., Ltd.). From the area of the obtained small pellets, the amount of small pellets was evaluated by the ratio (%) of the area of the small pellets on the target surface to the area of the target surface.

Sputtering is performed using DC magnetron sputtering.

Back pressure: 7.0 × 10 ^-5 [Pa]

Ar partial pressure: 4.0 × 10 ^-1 [Pa]

O ₂ partial pressure: 4.0 × 10 ^-5 [Pa]

Power: 300 [W] (1.6W / cm ² )

Target size: 203.2mm diameter, 6mm thickness

[Example 1]

In ₂ O ₃ powder with an average particle diameter of 0.6 μm and SnO ₂ powder with an average particle diameter of 0.8 μm obtained by pulverizing with a ball mill in advance were prepared so that the content of the SnO ₂ powder became 3.0% by mass as a binder. Add 0.3% by mass of the acrylic emulsion binder to the ceramic raw material powder, 0.5% by mass of the ammonium polycarboxylate as a dispersant to the ceramic raw material powder, and 20% by mass of the water as a dispersant to the ceramic raw material powder, and Mix to prepare a paste. This slurry was poured into a gypsum mold, and then drained to obtain a flat plate shaped body having a length of 350 mm, a width of 1000 mm, and a thickness of 10 mm.

Next, this formed body is dried and then fired to produce a fired body. The firing was performed in an oxygen environment at a temperature increase rate of 300 ° C / hour and a firing temperature of 1550 ° C for 10 hours. Thereafter, the temperature in the firing furnace was reduced to 30 ° C / hr until the temperature in the firing furnace reached 800 ° C to cool the fired body, and then the temperature in the firing furnace was brought to room temperature. Until then, the temperature in the firing furnace was lowered at a rate of 100 ° C / hr for cooling to obtain a sintered body.

Further, the obtained sintered body was cut to obtain a flat ITO target having a surface roughness Ra of 0.7 μm, a length of 280 mm, a width of 750 mm, and a thickness of 6 mm. The processing uses # 170's millstone.

The Sn content of the obtained ITO target was 3.0% by mass in terms of SnO ₂ , and it was confirmed that the Sn content was the same as that of the raw material.

This ITO target was evaluated as described above.

[Example 2]

Production and evaluation were performed in the same manner as in Example 1 except that SnO ₂ powder having an average particle diameter of 1.3 μm was used instead of SnO ₂ powder having an average particle diameter of 0.8 μm.

[Example 3]

Production and evaluation were performed in the same manner as in Example 1 except that SnO ₂ powder having an average particle diameter of 0.6 μm was used instead of SnO ₂ powder having an average particle diameter of 0.8 μm.

[Example 4]

Production and evaluation were performed in the same manner as in Example 1 except that the cooling rate after firing to 800 ° C was set to 50 ° C / hr.

[Example 5]

The production and evaluation were performed in the same manner as in Example 1 except that the content of the SnO ₂ powder was adjusted to 2.8% by mass.

[Example 6]

The production and evaluation were performed in the same manner as in Example 2 except that the content of the SnO ₂ powder was adjusted to 2.8% by mass.

[Example 7]

The production and evaluation were performed in the same manner as in Example 3 except that the content of the SnO ₂ powder was adjusted to 2.8% by mass.

[Example 8]

The production and evaluation were performed in the same manner as in Example 4 except that the content of the SnO ₂ powder was adjusted to 2.8% by mass.

[Example 9]

Production and evaluation were performed in the same manner as in Example 1 except that the content of the SnO ₂ powder was adjusted to 3.5% by mass.

[Example 10]

The production and evaluation were performed in the same manner as in Example 2 except that the content of the SnO ₂ powder was adjusted to 3.5% by mass.

[Example 11]

The production and evaluation were performed in the same manner as in Example 3 except that the content of the SnO ₂ powder was adjusted to 3.5% by mass.

[Example 12]

Production and evaluation were performed in the same manner as in Example 4 except that the content of the SnO ₂ powder was adjusted to 3.5% by mass.

[Comparative Example 1]

In addition to an average particle diameter of 0.8μm average particle diameter substituted SnO ₂ powder is a _powder of SnO 0.4μm, the rest of the system in the same manner as in Example 1 is manufactured, assessed.

[Comparative Example 2]

Production and evaluation were performed in the same manner as in Example 1 except that the cooling rate to 800 ° C after firing was set to 150 ° C / hr.

[Comparative Example 3]

The production and evaluation were performed in the same manner as in Example 1 except that the firing temperature was set to 1,450 ° C.

The evaluation results are shown in Table 1. In Comparative Examples 1 and 2 of Table 1, the targets were completely cracked during the bonding, so no small nodule generation was evaluated.

Claims (5)

An ITO sputtering target material, wherein the content of Sn is 2.8 to 3.5% by mass in terms of SnO _2. Among them, there are _two phases of a solid solution of SnO ₂ in In ₂ O ₃ and _two phases of In ₄ Sn ₃ O ₁₂ . The density is 98% or more, and the length of change due to strain relaxation is 50 μm or less per 1 m. The ITO sputtering target as described in the first item of the patent application scope, wherein the length of the change due to strain relaxation is 40 μm or less per 1 m. The ITO sputter target as described in the first or second scope of the patent application, wherein the flexural strength is 13.0 kgf / mm ² or more. The ITO sputter target as described in item 1 or 2 of the patent application scope, wherein the flexural strength is 14.0 kgf / mm ² or more. A method for manufacturing an ITO sputtering target is the method for manufacturing an ITO sputtering target according to any one of claims 1 to 4, and includes the following steps: The formed body made from the raw material for ITO production of the SnO ₂ raw material powder is fired in a firing furnace at a firing temperature of 1500 to 1600 ° C, and the temperature in the firing furnace reaches a temperature from the aforementioned firing temperature to 700 to 1100 ° C. Within the range, the temperature in the firing furnace is lowered at a temperature lowering rate of 60 ° C./hr or lower, thereby cooling the obtained fired body.