TW201638364A - ITO sputtering target material - Google Patents

Abstract

The ITO sputtering target material of this invention contains Sn in a content of, converted by SnO2, 2.8 to 3.5% by mass, which contains both of a phase of In2O3 solid-solved with SnO2 and a phase of In4Sn3O12, and has a relative density of 98% or more, and a change of length due to strain relaxation of 50[mu]m or less per 1m. Although the ITO sputtering target material of this invention contains Sn in a content of, converted by SnO2, 2.8 to 3.5% by mass, which is very easily to cause crack, the ITO sputtering target of the present invention is not easy to generate crack during bonding and has less generation of nodules, and therefor can efficiently form an ITO thin film.

Description

ITO sputtering target

The present invention relates to an ITO sputtering target, and more specifically, to an ITO sputtering target which is difficult to generate cracks upon bonding and which can form a film efficiently.

ITO (Indium-Tin-Oxide) film is widely used in transparent electrodes and touch panels of flat panel displays because of its high light transmittance and conductivity. The ITO film for a transparent electrode usually contains about 10% by mass of Sn in terms of SnO ₂ , but the ITO film used for the touch panel has a relationship with the heat treatment of the film, and the content of Sn is 2.5 to 8.0 in terms of SnO ₂ . The mass is about %.

The ITO film is generally formed by sputtering of an ITO sputtering target. The ITO sputtering target is generally used in conjunction with a support plate made of Cu. Therefore, when forming an ITO film for a touch panel, an ITO sputtering target which can achieve a Sn content of a target film impedance is generally bonded to a support plate made of Cu to perform sputtering.

However, it is known that the content of Sn is less than 10% by mass in terms of SnO ₂ , and the ITO sputtering target 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 remarkable, and it becomes a big obstacle in manufacturing a target. It is known that in such ITO sputtering targets, the reason for the firing of the manufacturing process is that residual stress is easily left, and the strength of the target is low. Therefore, these ITO sputtering targets are susceptible to cracking when they are bonded to a support plate made of Cu or the like.

Further, when the content of the sputtered Sn is less than 10% by mass in terms of SnO ₂ , the occurrence of nodule is also one of the problems. The occurrence of this small particle can be improved by increasing the density of the target. However, when the density of the target is increased, the residual stress becomes large, and the problem of cracking easily occurs.

Further, when the firing temperature is lowered and the firing density is as low as 97%, an ITO target having a small residual stress and being difficult to be cracked and having a small crystal structure can be obtained, but pinholes are increased in the target, which is a cause. There is a problem of an increase in the number of small particles at the time of sputtering. That is, it is difficult to crack the ITO target and suppress the relationship between the small granules.

Japanese Laid-Open Patent Publication No. Hei 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 diameter of the crystal or the maximum agglomerating diameter of the tin atom, but There is nothing to say about the cracked wire of the target.

In the ITO sintered body in which the content of tin oxide in indium oxide is 1.5% or more and 3.5% or less by mass ratio, the crystal phase of the sintered body is a single phase, 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 composed of the sintered body is not sufficiently suppressed in cracking.

[Previous Technical Literature] [Patent Literature]

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

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

An object of the present invention is to provide an ITO sputtering target which is 2.8 to 3.5% by mass in terms of Sn in terms of SnO ₂ in an ITO sputtering target, which is less likely to be cracked when combined, and is sputtered. The amount of small pellets is small.

The inventors of the present invention have found that an ITO sputtering target material has a content of Sn of 2.8 to 3.5% by mass in terms of SnO _{2 in} order to achieve the above object, wherein the target is in In ₂ O _{3 .} When the phase of the SnO ₂ phase and the _two phases of the In ₄ Sn ₃ O ₁₂ phase are solid-solved, the relative density of the target is 98% or more, and the change length due to the strain relaxation of the target is 50 μm or less per 1 m. purpose. Further, it has been found that in order to obtain physical properties thereof, it is necessary to cool the body after firing at 60 ° C / hr or less.

That is, 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 , and has a phase in which SnO ₂ is dissolved in In ₂ O ₃ and an In ₄ Sn ₃ O ₁₂ phase. In the two phases, the relative density is 98% or more, and the variation length due to strain relaxation is 50 μm or less per 1 m.

It is preferable that the ITO sputtering target has a variation length due to strain relaxation of 40 μm or less per 1 m.

The ITO sputtering target has a flexural strength of preferably 13.0 kgf/mm ² or more, more preferably 14.0 kgf/mm ² or more.

Another invention is a method for producing the ITO sputtering target, comprising the steps of: forming a shaped body from a raw material for ITO production containing a SnO ₂ raw material powder having an average particle diameter of 0.5 μm or more, in a firing furnace at 1500 to Firing at a firing temperature of 1600 ° C, the temperature in the firing furnace is from the above-mentioned firing temperature to a temperature range of 700 to 1100 ° C, so that the temperature in the firing furnace is lowered at a cooling rate of 60 ° C / hr or less. This cooled the resulting fired body.

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 , which is extremely susceptible to cracking, and is difficult to be cracked when combined, and the generation of small particles in sputtering is small. Therefore, the ITO film can be efficiently formed into a film. The method for producing an ITO sputtering target of the present invention can produce the aforementioned target extremely efficiently.

1‧‧‧ variable gauge

2‧‧‧Wiring

3‧‧‧ Target fragment

Fig. 1 is an explanatory view showing a method of measuring the length of change caused by strain relaxation.

The ITO sputtering target (hereinafter also referred to as ITO target) of the present invention is an ITO target having a content of Sn of 2.8 to 3.5% by mass in terms of SnO ₂ and having SnO dissolved in In ₂ O ₃ . The phase of ₂ and the _two phases of the 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 small.

As described above, the conventional ITO target having a content of Sn of 2.8 to 3.5% by mass in terms of SnO ₂ is likely to cause residual stress and low strength, so that it is fragile and easily cracked. When the ITO target is produced, when the firing temperature is lowered and the relative density of the target is 97% or less, the residual stress is small and cracking is unlikely, but the small particles at the time of sputtering increase. When the relative density of the ITO target is 98% or more, the small particles at the time of sputtering are reduced, but the residual stress is increased or cracking is likely to occur. In other words, in the conventional ITO target in which the content of Sn is 2.8 to 3.5% by mass in terms of SnO ₂ , the cracking difficulty and the suppression of the small particles are not able to coexist.

In the present invention, in the ITO target having a Sn content of 2.8 to 3.5% by mass in terms of SnO ₂ , the cracking difficulty and the suppression of the small particles are successfully coexisted. Difficulty and cracking suppressed coexist based measure of the initial particles by ITO target having an In ₂ O ₃ in a solid solution phase of SnO _2, and the Sn content than the In ₂ O ₃ in a solid solution phase having minute SnO ₂ of More phases of the In ₄ Sn ₃ O ₁₂ phase are achieved in a two-phase manner.

The production of ITO is usually carried out by producing a molded body from a mixed powder of In ₂ O ₃ powder and SnO ₂ powder, and firing the molded body. In this firing, SnO ₂ is gradually dissolved 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 It can be formed into an In ₄ Sn ₃ O ₁₂ phase rich in Sn phase. As a result, SnO ₂ content of SnO ₂ in terms of 10% based ITO having a two-phase matrix phase and In ₄ Sn ₃ O ₁₂ phase of. On the other hand, in the 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 is completely dissolved in In ₂ O ₃ , so that 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 The two phases, and the relative density of 98% or more, succeeded in producing an ITO target having a change length of strain relaxation which is an index of residual stress of 50 μm or less per 1 m. As a result, in the ITO target having a content of SnO ₂ of 2.8 to 3.5% by mass, cracking difficulty and suppression of small particles can be prevented.

The ITO target having a content of SnO ₂ of 2.8 to 3.5% by mass is a structure having a phase in which SnO ₂ is dissolved in In ₂ O ₃ and a phase of In ₄ Sn ₃ O ₁₂ phase, whereby the turtle can be made The reasons for the difficulty of cracking and the inhibition of the coexistence of small particles are not necessarily clear, but it is considered that in such a structure, the In ₄ Sn ₃ O ₁₂ phase exists in the grain boundary of the phase in which SnO ₂ is solid-dissolved in In ₂ O ₃ , and thus is not It is enhanced by the action of the wedge of In ₂ O ₃ solid solution in which the phases of SnO ₂ are bonded to each other. As a result, it is considered that the ITO target having two phases can be suppressed by the density of the ITO target, and on the other hand, even if residual stress is generated, if it is a certain value or less, it is not available. It is difficult to crack the characteristics. For example, ITO having a content of Sn of 10% in terms of SnO ₂ is generally more resistant to cracking than ITO having a content of SnO ₂ of 2.8 to 3.5% by mass. The former ITO is as described above, and is made of In ₂ O _{3 .} The _two phases of the SnO ₂ phase and the In ₄ Sn ₃ O ₁₂ phase are dissolved in the solid solution, and the In ₄ Sn ₃ O ₁₂ phase functions as described above.

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

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

The ITO target of the present invention has a variation length due to strain relaxation of 50 μm or less per 1 m, and preferably 40 μm or less per 1 m. The length of change due to strain relaxation means the difference between the length of the ITO target before release and the length of the released ITO target when the residual stress of the ITO target is substantially completely released. The length of change due to strain relaxation is a physical property value that is an indicator of residual stress. The length of change due to strain relaxation can be determined using a strain gauge. The method for determining the length of change of the ITO target by strain relaxation is detailed in the examples. As described above, the ITO target of the present invention has _two phases of a phase in which SnO ₂ is dissolved and a phase of In ₄ Sn ₃ O ₁₂ in In ₂ O ₃ , so that even if residual stress is present, cracking is not easy, but there is When the length of change due to strain relaxation is a large residual stress exceeding 50 μm per 1 m, the probability of occurrence of cracks in the subsequent processing or bonding step becomes high.

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

The shape and size of the ITO target of the present invention are not particularly limited, and even if the ITO target of any shape and size satisfies the above conditions, it can achieve the object of the invention. The shape may be, for example, a flat plate shape or a cylindrical shape.

Hereinafter, a method of producing the ITO target of the present invention will be described in detail.

The method for producing an ITO target of the present invention comprises the steps of: firing a molded body obtained from a raw material for ITO production containing a SnO ₂ raw material powder having an average particle diameter of 0.5 μm or more at a temperature ranging from 1,500 to 1,600 ° C, The obtained fired body was further cooled at a temperature decreasing rate of 60 ° C / hr or less. By the above manufacturing method, the above ITO target can be produced.

The raw material for ITO production contains SnO ₂ powder, and usually contains In ₂ O ₃ powder and SnO ₂ powder. The In ₂ O ₃ powder of the raw material powder and the SnO ₂ powder were mixed so that the content of the SnO ₂ powder was 2.8 to 3.5% by mass to prepare a mixed powder. Since the particles of the respective raw material powders are usually aggregated, it is preferably pulverized and mixed beforehand or pulverized while being mixed.

The average particle diameter of the In ₂ O ₃ powder is usually from 0.2 to 1.5 μm, preferably from 0.4 to 1.0 μm. The SnO ₂ powder has an average particle diameter of 0.5 μm or more, preferably 0.5 μm to 5.0 μm, more preferably 0.6 μm to 2.0 μm. In the method for producing an ITO target of the present invention, in order to obtain an ITO target having _two phases of a SnO ₂ solid solution phase and an In ₄ Sn ₃ O ₁₂ phase in In ₂ O ₃ , the average particle diameter of the SnO ₂ powder must be 0.5 μm or more. When the average particle diameter of the SnO ₂ powder is 0.5 μm or more, an In ₄ Sn ₃ O ₁₂ phase in which a Sn-rich phase is formed is formed at the time of firing. When this system that the average particle diameter of SnO ₂ powder was 0.5μm or more, the formed body of the firing process, not completely dissolved in the SnO ₂ In ₂ O _3, without forming a complete solid solution of SnO ₂ 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 the SnO ₂ powder is less than 0.5 μm, SnO _{2 is} easily dissolved in In ₂ O ₃ during the firing of the formed body, and at least a majority of the SnO ₂ is dissolved in In ₂ O. ₃ reasons. Therefore, it is necessary to use a SnO ₂ powder having a large average particle diameter of 0.5 μm or more. Further, the above average particle diameter is a volume cumulative particle diameter D50 in a cumulative volume of 50% by volume obtained by a laser diffraction scattering type particle size distribution measurement method.

The pulverization method or the mixing method of the raw material powder is not particularly limited. For example, the raw material powder may be placed in a crucible and pulverized or mixed by a ball mill.

The mixed powder may be directly molded into a molded body and then sintered. However, if necessary, a binder may be added to the mixed powder to form a molded body. As the binder, a binder which is used in obtaining a molded body in a known powder metallurgy method, for example, a polyvinyl alcohol, an acrylic emulsion binder or the like can be used. Further, the obtained molding system can be degreased as needed in a known powder metallurgy method. The forming method can also be carried out by a method known in the powder metallurgy method, for example, casting molding. The density of the shaped body is usually from 50 to 75%.

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

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

After the completion of the firing, the temperature in the firing furnace is from a temperature range of 700 to 1100 ° C, for example, 800 ° C, and the temperature in the firing furnace is 60 ° C / hr or less. The obtained fired body was cooled by lowering at 30 ° C / hr or less. By cooling at a temperature drop rate in this range, the length of change in strain relaxation of the sintered body can be reduced, and it can be made 50 μm or less per 1 m. The rate of decrease in the temperature in the firing furnace is not particularly limited as long as it can prevent cracking of the fired body, and can be, for example, 50 to 150 ° C / hr.

The ITO sintered body obtained in this manner 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 sheet. The support plate is usually made of Cu, Al, Ti or stainless steel. The bonding material can use a bonding material such as In metal used in combination with a conventional ITO target. The bonding method is also the same as the conventional ITO target. For example, the ITO target and the support plate of the present invention are heated until the temperature at which the bonding material melts, for example, about 200 ° C, and the bonding materials are applied to the respective bonding faces of the target and the supporting plate, and the respective bonding faces are pressed to be pressed. After the two, cool down. Or, in The bonding surface of the ITO target and the support plate of the present invention is coated with a bonding material to adhere to the respective bonding faces, and the target and the supporting plate are heated until the bonding agent melts at a temperature of, for example, about 200 ° C. cool down.

[Examples]

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 (the weight of the water in the target / the specific gravity of the water in the measured temperature), and the percentage relative to the theoretical density ρ (g/cm ³ ) according to the following formula (X) The value is set to relative density (unit: %).

ρ=((C1/100)/ρ1+(C2/100)/ρ2+‧‧‧+(Ci/100)/ρi) ^-1 (X) (wherein C1 to Ci represent the content of the constituent materials of the target, respectively (wt%), ρ 1 ρ i lines to indicate corresponding to the density of the constituent substances of C1 to Ci (g / cm ^3).)

2. Average particle size of raw material powder

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

3. Determination of bending strength

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

4. Specificity of the target structure (crystalline phase)

The phase in which SnO _{2 was} dissolved in In ₂ O ₃ was observed by an electron microscope. Further, the specificity of the In ₄ Sn ₃ O ₁₂ phase is carried out by investigating the distribution of Sn by the Auger electron spectroscopy.

It was confirmed that the phase in which SnO ₂ was dissolved in In ₂ O ₃ and the In ₄ Sn ₃ O ₁₂ phase were evaluated as "two phases", and only when the phase in which SnO ₂ was dissolved in In ₂ O ₃ was confirmed. The assessment is "single phase".

5. The length of change caused by the strain relaxation of the target (1 gauge method 2-wire type)

Apply a variable gauge to the surface of the cleaned target with a special adhesive (N 11-FA-2-120-VSE 1, nominal resistance 120Ω, gauge rate 2.0/Avionics, Japan), with diamond sawtooth machine Cutting the target. As shown in Fig. 1, the cutting system is performed so as to obtain the target piece 3 of 20 × 20 mm in the direction parallel to the four sides of the strain gauge 1 centering on the strain gauge 1 on which the wiring 2 is attached. The change in the length of the target produced by the release of the strain by the cutting of the target was measured by a data recorder (remote scanner DC6100/manufactured by Avionics, Japan) to which the wiring 2 was connected. The measurement was carried out at room temperature (25 ° C).

6. Cracking of the target when combined

A plate-shaped support plate made of Cu having a sufficient area in combination with the target is combined with the target by the following method. The target and the support plate were heated to 160 ° C, and In solder was applied as a bonding material to the respective bonding faces of the target and the substrate, and the respective bonding faces were bonded to each other to be pressed, and then cooled. The target was visually observed for cracking at the time of bonding. When the crack was confirmed, it was evaluated as "Yes" and was not confirmed. The time is evaluated as "None."

7. Evaluation of the occurrence of small pellets

The ITO target which was not cracked at the time of bonding was cut into a small particle size by a wire cutter, and sputtered under the following conditions. The surface of the target material after the photolithography was imaged, and the area of the small particle was obtained from the obtained image by image analysis software (particle analysis version, manufactured by Tiejinjin 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 particles on the surface of the target with respect to the area of the surface of the target.

Sputtering is performed using DC magneto-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]

Electricity: 300 [W] (1.6 W / cm ² )

Target size: diameter 203.2mm, thickness 6mm

[Example 1]

In ₂ O ₃ powder having an average particle diameter of 0.6 μm obtained by pulverizing in a ball mill in advance, and SnO ₂ powder having an average particle diameter of 0.8 μm were blended so as to have a content of SnO ₂ powder of 3.0% by mass, as a binder. The acrylic emulsion binder is added to the ceramic raw material powder in an amount of 0.3% by mass, the polycarboxylate as a dispersing agent is added to the ceramic raw material powder in an amount of 0.5% by mass, and the water as a dispersing agent is added in an amount of 20% by mass based on the ceramic raw material powder, and Mixing is carried out to prepare a paste. This slurry was poured into a plaster mold, and then drained to obtain a flat molded body having a length of 350 mm, a width of 1000 mm, and a thickness of 10 mm.

Next, the molded body is dried and then fired to prepare a fired body. The firing was carried out in an oxygen atmosphere at a heating rate of 300 ° C / hour and a firing temperature of 1550 ° C for 10 hours. Thereafter, the temperature in the firing furnace is lowered at a rate of 30 ° C/hr by the temperature in the firing furnace to reach a temperature of 30 ° C to cool the fired body, and then the temperature in the furnace is heated to room temperature. The temperature in the firing furnace was lowered at a rate of 100 ° C / hr to cool, and a sintered body was obtained.

Further, the obtained sintered body was subjected to a cutting process to obtain a flat ITO target having a surface roughness Ra of 0.7 μm and a longitudinal direction of 280 mm, a width of 750 mm, and a thickness of 6 mm. The processing system uses a #170 millstone.

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

For this ITO target, the above evaluation was performed.

[Embodiment 2]

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

[Example 3]

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

[Example 4]

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

[Example 5]

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

[Embodiment 6]

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

[Embodiment 7]

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

[Embodiment 8]

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

[Embodiment 9]

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

[Embodiment 10]

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

[Embodiment 12]

The production and evaluation were carried out 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]

The production and evaluation were carried out in the same manner as in Example 1 except that the SnO ₂ powder having an average particle diameter of 0.4 μm was used instead of the SnO ₂ powder having an average particle diameter of 0.8 μm.

[Comparative Example 2]

The production and evaluation were carried out in the same manner as in Example 1 except that the cooling rate to 800 ° C after firing was 150 ° C / hr.

[Comparative Example 3]

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

The evaluation results are shown in Table 1. In Comparative Examples 1 and 2 of Table 1, the target was completely cracked at the time of bonding, so that the amount of small particle generation was not evaluated.

1‧‧‧ variable gauge

2‧‧‧Wiring

3‧‧‧ Target fragment

Claims (5)

An ITO sputtering target material having a content of Sn of 2.8 to 3.5% by mass in terms of SnO ₂ , wherein the phase of the solid solution of SnO _{2 and} the phase of the In ₄ Sn ₃ O ₁₂ phase in In ₂ O ₃ is relatively 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 according to the first aspect of the invention, wherein the length of change due to strain relaxation is 40 μm or less per 1 m. The ITO sputtering target according to claim 1 or 2, wherein the bending strength is 13.0 kgf/mm ² or more. The ITO sputtering target according to any one of claims 1 to 3, wherein the bending strength is 14.0 kgf/mm ² or more. A method for producing an ITO sputtering target according to any one of claims 1 to 4, further comprising the steps of: containing an average particle diameter of 0.5 μm or more SnO ₂ ITO raw material powder for producing the raw material of the molded body produced in a firing furnace at a firing temperature of 1500 to 1600 ℃ firing, the firing temperature in the furnace from the sintering temperature reaches the temperature of 700 to 1100 ℃ In the range, the temperature in the firing furnace is lowered at a cooling rate of 60 ° C / hr or less, whereby the obtained fired body is cooled.