TWI814561B - Oxide sintered body, manufacturing method thereof, and sputtering target - Google Patents

Abstract

The present invention provides an oxide sintered body, which contains indium (In) element, tin (Sn) element and silicon (Si) element, and the Sn content is 50 mass% or more and 70 mass% or less in terms of _SnO2 , and the Si content is In terms of SiO ₂ , it is 3% by mass or more and 15% by mass or less. The remainder includes indium, oxygen and unavoidable impurities. The area ratio of the SiO ₂ phase observed in the cross section of the above-mentioned oxide sintered body is 3% or less. The present invention uses This oxide sintered body constitutes a sputtering target.

Description

Oxide sintered body and manufacturing method thereof and sputtering target material

The present invention relates to an oxide sintered body and a manufacturing method thereof. Furthermore, the present invention relates to a sputtering target.

Composite oxides containing indium and tin (hereinafter also referred to as "ITO (Indium Tin Oxides, indium tin oxide)") are widely used as materials for transparent conductive films. For example, the transparent conductive film used in a flat panel display (hereinafter also referred to as "FPD") is selected to have low resistance (resistivity of approximately 2×10 ^-4 Ωcm). On the other hand, transparent conductive films for resistive touch panels mounted on FPDs, etc., require high resistance (sheet resistance of about 700Ω to 1000Ω) as a required characteristic in principle.

Therefore, the applicant first proposed a sputtering target that has a low specific resistance capable of DC (Direct Current) sputtering and can form a transparent conductive film with a high film specific resistance (refer to patent documents 1). The target is composed of a composite oxide containing silicon in addition to indium and tin.

[Prior technical literature] [Patent Document]

[Patent Document 1] International Publication No. 2018/211792

In addition, when a thin film is formed by sputtering, abnormal discharge generated during sputtering is one of the phenomena cited as a problem. This phenomenon is not a problem if the target material described in Patent Document 1 is used, but from the viewpoint of improving film productivity, it is required to further reduce this phenomenon.

Therefore, an object of the present invention is to provide a sputtering target in which the occurrence of abnormal discharge is further suppressed compared to the above-described prior art. Furthermore, an object of the present invention is to provide an oxide sintered body suitable for such a target material and a method for producing the same.

The present invention provides an oxide sintered body, which contains indium (In) element, tin (Sn) element and silicon (Si) element, and the Sn content is 50 mass% or more and 70 mass% or less in terms of _SnO2 , and the Si content is In terms of SiO ₂ , it is 3 mass % or more and 15 mass % or less, and the remainder includes indium, oxygen, and unavoidable impurities. The area ratio of the SiO ₂ phase observed in the cross section of the above-mentioned oxide sintered body is 3% or less.

Furthermore, the present invention provides a sputtering target material including the above-mentioned oxide sintered body.

Furthermore, the present invention provides a method for manufacturing an oxide sintered body, which includes the following steps: preparing a raw material composition including an indium (In) element source, a tin (Sn) element source, and a silicon (Si) element source, and combining the above raw materials. The object is formed to obtain a shaped body, and the above shaped body is calcined; and The above-mentioned molded body is calcined at a temperature of not less than 1450°C and not more than 1500°C for not less than 4 hours but not more than 20 hours.

~

)的模式圖。 Figure 1 shows the measurement positions of the volume resistance of the sputtering targets obtained in the Examples and Comparative Examples (

~

) pattern diagram.

The oxide sintered body of the present invention and the sputtering target made using the same include indium (In) element, tin (Sn) element and silicon (Si) element. These elements alone form oxides, or two or more elements form composite oxides.

The Sn content ratio of the oxide sintered body of the present invention and the sputtering target produced using the same is 50 mass% or more and 70 mass% or less in terms of SnO ₂ , preferably 52 mass% or more and 68 mass% or less, still more preferably It is 55 mass % or more and 65 mass % or less, and it is more preferable that it is 57 mass % or more and 63 mass % or less.

By setting the content ratio of Sn to 50% by mass or more, the film specific resistance of the transparent conductive film obtained by sputtering the oxide sintered body and the sputtering target using the same can be increased, and can be used for installation in Transparent conductive film for resistive touch panels used in FPD, etc.

By setting the Sn content ratio to 70% by mass or less, the specific resistance of the oxide sintered body and the sputtering target made using it can be prevented from increasing, DC sputtering can be easily performed, and the advantages of DC sputtering can be enjoyed. High-speed film formation and other advantages.

The Si content ratio of the oxide sintered body of the present invention and the sputtering target made using the same is 3 mass % or more and 15 mass % or less in terms of SiO ₂ , preferably 4 mass % or more and 13 mass % or less, more preferably It is 6 mass % or more and 12 mass % or less, and it is more preferable that it is 7 mass % or more and 11 mass % or less.

By setting the content ratio of Si to 3% by mass or more, the film specific resistance of the transparent conductive film obtained by sputtering the oxide sintered body and the sputtering target using the same can be increased, and can be used for installation in Transparent conductive film for resistive touch panels used in FPD, etc.

By setting the Si content ratio to 15% by mass or less, as explained below, the area ratio of the SiO ₂ phase in the oxide sintered body and the sputtering target made using the same can be reduced, that is, in the sintered body and the sputtering target. The area ratio in the target material is 3% or less, which can effectively suppress abnormal discharge when sputtering the target material. In addition, the specific resistance can be suppressed from increasing, DC sputtering can be easily performed, and DC sputtering can achieve high-speed film formation, etc. advantages.

Furthermore, the remainder of the oxide sintered body of the present invention and the sputtering target produced using the same contains In, O, and unavoidable impurities.

The content ratio of In in the sputtering target material is preferably 15 mass % or more and 47 mass % or less in terms of In ₂ O ₃ , more preferably 19 mass % or more and 44 mass % or less, and still more preferably 23 mass % or more 39 mass% or less, more preferably 26 mass% or more and 36 mass% or less.

Examples of unavoidable impurities include Fe, Cr, Ni, W, and Zr, and their contents are usually 100 ppm or less.

The oxide sintered body of the present invention and the sputtering target produced using the same preferably contain a composite oxide phase of In and Si, a composite oxide phase of In and Sn, an oxide phase of Sn, and an oxide phase of Si. , which can effectively suppress abnormal discharge when sputtering the target, which is preferable in this aspect. From the viewpoint of making this advantage more remarkable, it is preferable to include an In ₂ Si ₂ O ₇ phase as a composite oxide phase of In and Si. It is preferable to include an In ₄ Sn ₃ O ₁₂ phase as a composite oxide phase of In and Sn. Preferably, a SnO ₂ phase is included as the oxide phase of Sn. Preferably, a SiO ₂ phase is included as the oxide phase of Si.

Regarding the oxide sintered body of the present invention and the sputtering target made using the same, the area ratio of the SiO ₂ phase observed in the cross section of the oxide sintered body is preferably 3% or less, more preferably 0.1% or more. 2.8% or less, more preferably 0.5% or more and 2.5% or less, particularly preferably 0.6% or more and 2.4% or less. The smaller the area ratio of the SiO ₂ phase, the better. However, the lower limit of the above preferred range is determined by the fact that the oxide sintered body, etc. contains Si within the above range.

By setting the area ratio to 3% or less, abnormal discharge during DC sputtering on the sputtering target can be effectively suppressed. The reason for this is that since the SiO ₂ phase is an insulating layer, even when the resistivity of the oxide sintered body and the sputtering target made using the same is as low as about 10 ^-1 Ωcm, if the area ratio of the SiO ₂ phase If it exceeds 3%, the discharge stability will also become worse and abnormal discharge will easily occur.

The relative density of the oxide sintered body of the present invention and the sputtering target produced using the same is preferably 100% or more, more preferably 100.5% or more, and particularly preferably 101.0% or more. By setting the relative density to 100% or more, abnormal discharge during DC sputtering on the sputtering target can be effectively suppressed. The reason is that as the relative density increases, the volume resistance value of the oxide sintered body and the sputtering target made using it decreases, thereby suppressing charge concentration during DC sputtering. The reason is that there are high potential areas caused by charge concentration during DC sputtering and due to the lack of charge concentration. The formation of the resulting low-potential parts is suppressed, and discharge from the high-potential part to the low-potential part is less likely to occur. Therefore, it is believed that abnormal discharge is suppressed.

Relative density is determined by Archimedes' method. Specifically, the mass of the target in the air is divided by the volume (mass of the target in water/specific gravity of water at the measurement temperature) to determine the percentage relative to the theoretical density ρ (g/cm ³ ) based on the following formula (X) Value as relative density (unit: %).

(In the formula, C ₁ ~C _i respectively represent the content (mass %) of the constituent materials of the target, and ρ ₁ ~ρ _i represent the density of each constituent material corresponding to C ₁ ~C _i (g/cm ³ ))

Regarding the constituent materials of the oxide sintered body and the sputtering target made using the same, as described below, in terms of In ₂ O ₃ , SnO ₂ , and SiO ₂ , for example, the following parameters can be applied to the formula ( X) to calculate the theoretical density ρ, C ₁ : mass % of In ₂ O ₃ of the target material

ρ ₁ : Density of In ₂ O ₃ (7.18g/cm ³ )

C ₂ : Mass % of SnO ₂ in the target material

ρ ₂ : Density of SnO ₂ (6.95g/cm ³ )

C ₃ : Mass % of SiO ₂ in the target material

ρ ₃ : Density of SiO ₂ (2.20g/cm ³ ).

The mass % of In ₂ O ₃ , the mass % of SnO ₂ and the mass % of SiO ₂ of the target material can be determined based on the ratio of each element of the target material obtained by ICP (Inductively Coupled Plasma, inductively coupled plasma) emission spectroscopy. Find out by analyzing the results.

The upper limit of the relative density is not particularly limited, but is, for example, 104.0%. Even if the relative density is further increased from 104.0%, it is difficult to effectively improve the above-mentioned effects, and the manufacturing cost of the oxide sintered body and the sputtering target made of it tends to increase.

Regarding the oxide sintered body of the present invention and the sputtering target made using the same, when the relative density of the oxide sintered body is ρ _T and the oxide sintered body is divided into a plurality of measurement pieces, these measurements are When the relative density of the sheet whose value deviates the most from the relative density ρ _T mentioned above is ρ _P , the difference in relative density defined by the following formula (1) is preferably ±1% or less, and further preferably ±0.5% or less, preferably ±0.3% or less.

ρ _T -ρ _P (1)

By reducing the above-mentioned difference in relative density, the charge concentration of the oxide sintered body and the sputtering target made using it is suppressed, and the high potential portion caused by the charge concentration and the low potential caused by the unconcentrated charge are suppressed. The formation of the parts makes it difficult for discharges from high potential parts to low potential parts, thereby suppressing abnormal discharges.

Regarding the oxide sintered body of the present invention and the sputtering target made using the same, the largest body resistance value among the body resistance values measured at a plurality of locations on the surface is set to Rmax, and the smallest resistance value is set to Rmax. When Rmin is used, the value of Rmax/Rmin is preferably from 1.0 to 2.0, more preferably from 1.1 to 1.8, and particularly preferably from 1.2 to 1.6. By setting the value of Rmax/Rmin to the upper The above range can effectively suppress abnormal discharge when DC sputtering is performed on the above sputtering target.

The reason for this is that if the deviation in the volume resistance of the oxide sintered body and the sputtering target made using it increases, the potential of the high-resistance part will increase and the potential of the low-potential part will decrease, so it is easy to occur from the high-potential part. On the other hand, if the variation in the body resistance value of a discharge to a low-potential part is reduced, the above-mentioned discharge is less likely to occur, and it is considered that abnormal discharge is suppressed.

Furthermore, the Vickers hardness of the surface of the oxide sintered body of the present invention and the sputtering target produced using the same is preferably 900 HV1 or more, more preferably 950 HV1 or more, and particularly preferably 1000 HV1 or more. It is preferable to set the Vickers hardness of the oxide sintered body and the sputtering target made using the oxide sintered body to 900 HV1 or more to prevent cracking of the sputtering target during sputtering.

The upper limit of the Vickers hardness of the oxide sintered body and the sputtering target made using the same is not particularly limited, but is, for example, 1100 HV1. Even if the surface hardness is further increased compared to 1100 HV1, it is difficult to effectively improve the above-mentioned effects, and the manufacturing cost of the oxide sintered body and the sputtering target made of it tends to increase.

The area of the sputtering surface of the sputtering target of the present invention is preferably 70,000 mm ² or more, more preferably 120,000 mm ² or more, further preferably 157,500 mm ² or more, particularly preferably 200,000 mm ² or more. By this, when a plurality of pieces of the sputtering target are used to produce a large-area divided sputtering target, the number of gaps between adjacent targets can be reduced, and the effects of gaps between adjacent targets during sputtering can be suppressed. particles produced.

The upper limit of the area of the sputtering surface is not particularly limited, but is usually 500000 mm ² .

By allowing the oxide sintered body of the present invention and the sputtering target made using the same to have the above characteristics, it is possible to provide a sputtering target in which the generation of abnormal discharge is further suppressed, and to provide a target suitable for such a target. Oxide sintered body.

The oxide sintered body of the present invention and the sputtering target using the same can be appropriately produced by the following method.

First, prepare an indium (In) element source, a tin (Sn) element source, and a silicon (Si) element source. Generally speaking, the indium (In) element source, tin (Sn) element source and silicon (Si) element source can be In ₂ O ₃ powder, SnO ₂ powder and SiO ₂ powder. In ₂ O ₃ powder, SnO ₂ powder and SiO ₂ powder are mixed so that the contents of In, Sn and Si in the obtained sintered body are respectively within the above ranges to prepare a raw material composition. Confirm the In content ratio of the indium (In) element source, tin (Sn) element source and silicon (Si) element source in the raw material composition to the In content in terms of In ₂ O ₃ and Sn content in terms of SnO ₂ in the oxide sintered body, respectively. The ratio is consistent with the Si content ratio converted to SiO ₂ .

Since particles usually agglomerate, each raw material powder is preferably pulverized and mixed in advance, or pulverized while mixing.

The method of grinding the raw material powder or the mixing method when obtaining the raw material composition is not particularly limited. For example, the raw material powder can be put into a tank and pulverized or mixed using a ball mill.

When preparing the above raw material composition, it is preferable to add fatty acids to the indium (In) element source, tin (Sn) element source and silicon (Si) element source, such as In ₂ O ₃ powder, SnO ₂ powder and SiO ₂ powder. , preferably a saturated fatty acid with a carbon number of 10 to 22. By adding fatty acids, the surface lubricity of each element source is increased, so each element source is included in the raw material composition in a uniform and dense state, and the uniformity and density of the raw material composition are improved. Therefore, uneven calcination of the raw material composition can be suppressed, and the relative density difference or Rmax/Rmin of the above-mentioned oxide sintered body can be simply brought into the above-mentioned preferred range, thereby improving the flexural strength.

Examples of saturated fatty acids include capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, and the like. These saturated fatty acids can be used individually by 1 type, or in combination of 2 or more types. In addition to saturated fatty acids, unsaturated fatty acids such as palmitoleic acid, oleic acid, elaidic acid, vaccenic acid, sinapic acid, linoleic acid, sublinolenic acid, and arachidonic acid can also be used. In particular, from the viewpoint of ease of acquisition, stearic acid is preferably used, and industrial stearic acid (stearic acid + palmitic acid) is more preferably used. These unsaturated fatty acids can be used individually by 1 type, or in combination of 2 or more types. Saturated fatty acids and unsaturated fatty acids may be used in combination of one or more types.

The obtained raw material composition can also be directly formed into a shaped body and sintered. However, if necessary, a binder can also be added to the raw material composition to be shaped into a shaped body. As the binder, one or two or more binders used when obtaining molded bodies by known powder metallurgy methods, such as polyvinyl alcohol and acrylate emulsion binders, can be used. Alternatively, a dispersion medium may be added to the mixed powder to prepare a slurry, and the slurry may be spray-dried to produce particles, and the particles may be formed.

The forming method may be a method previously used in powder metallurgy, such as cold pressing or CIP (cold equalization press forming).

Alternatively, the raw material composition may be temporarily pressurized to produce a temporary molded body, and then the pulverized powder obtained by pulverizing the raw material composition may be fully pressurized to produce a molded body. Furthermore, a wet molding method such as slip molding can also be used to produce the molded body. The relative density of the formed body is usually 50~75%.

By calcining the formed body obtained in the above manner, a sintered body can be obtained. The calcining furnace used for calcining is not particularly limited as long as it can control the heating rate and cooling rate during calcining and cooling. It can be a calcining furnace commonly used in powder metallurgy. The calcining atmosphere is preferably an oxygen-containing atmosphere.

From the viewpoint of high density and prevention of cracking, the heating rate is usually 50 to 400°C/h, and the cooling rate is usually 300°C/h or less, preferably 100°C/h or less.

The calcination temperature is not less than 1450°C and not more than 1500°C, preferably not less than 1460°C and not more than 1490°C. Moreover, the calcination time is from 4 hours to 20 hours, preferably from 8 hours to 18 hours. By setting the calcination temperature and calcination time within the above range, it is possible to suppress the transformation of the In ₂ Si ₂ O ₇ phase into the SiO ₂ phase. As mentioned above, the SiO ₂ phase observed in the cross section of the oxide sintered body is The area ratio is set to 3% or less.

The sputtering target material can be obtained by cutting the sintered body obtained in the above manner into a desired shape and grinding it if necessary.

The shape of the sputtering target is flat plate, cylindrical, etc., and is not particularly limited.

Sputtering targets are generally used bonded to a base material. The base material is usually made of Cu, Al, Ti or stainless steel. The joining material used in the past for joining ITO targets, such as In metal, can be used. The bonding method is also the same as that of the previous ITO target.

Since the above-mentioned sputtering target has a low specific resistance, DC sputtering can be performed and high-speed film formation can be achieved. Furthermore, since the above characteristics are satisfied, the occurrence of abnormal discharge can be further suppressed.

[Example] [Evaluation of sputtering targets] 1. Elemental analysis of sputtering targets

The elemental analysis in the sputtering target material uses a measuring machine (name, model): ICP emission spectrometer analysis device 720 ICP-OES (machine manufacturer: Agilent Technologies), and is based on JIS (Japanese Industrial Standards, Japanese Industrial Standards) standards : ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometer, Inductively Coupled Plasma Atomic Emission Spectrometer) method (JIS K 0116-2014).

2. Crystal phase of sputtering target material

The crystal phase of the sputtering target was measured under the following conditions using SmartLab (registered trademark) of Rigaku Co., Ltd.

‧Radioactive source: CuKα rays

‧Tube voltage: 40kV

‧Tube current: 30mA

‧Scan speed: 5deg/min

‧Step size: 0.02deg

‧Scanning range: 2θ=20 degrees ~ 80 degrees

3. SiO ₂ phase area ratio of sputtering target

Use sandpaper #180, #400, #800, #1000, and #2000 to grind the cut surface obtained after cutting the sputtering target material in stages, and finally polish and grind it to a mirror surface.

Then, for the surface that appeared, a scanning electron microscope (SU3500, manufactured by Hitachi High-Technology Co., Ltd.) was used to randomly capture BSE-COMP images of 10 fields of view with a magnification of 3000 times and a range of 41.6 μm × 59.2 μm. Obtain SEM (scanning electron microscope, scanning electron microscope) image. Next, Pictbear (manufactured by Fenrir Corporation) was used to draw and color the range occupied by the SiO ₂ phase in different colors. Next, using particle analysis software (Particle Analysis Version 3.0, manufactured by Sumitomo Metal Technology Co., Ltd.), the image obtained by coloring the SiO ₂ phase was recognized, and the image was binarized. At this time, set the conversion value so that one pixel is expressed in μm units. Thereafter, particle analysis software was used to calculate the areas of the SiO ₂ phase and the whole, respectively, and the percentage of the SiO ₂ phase relative to the whole was calculated as the area ratio. The average value of the area ratios obtained in 10 visual fields was used as the area ratio of the SiO ₂ phase in the sintered body.

4. Relative density of sputtering target and its deviation

Determined by Archimedes' method. Specifically, the mass of the target in the air is divided by the volume (mass of the target in water/specific gravity of water at the measurement temperature) to determine the percentage relative to the theoretical density ρ (g/cm ³ ) based on the following formula (X1) Value as relative density (unit: %).

In the case of the present invention, the theoretical density ρ can be calculated by applying the following parameters to the formula (X1), for example, in terms of In ₂ O ₃ , SnO ₂ , and SiO ₂ as constituent substances of the target.

C ₁ : Mass % of In ₂ O ₃ of the target material

ρ ₁ : Density of In ₂ O ₃ (7.18g/cm ³ )

C ₂ : Mass % of SnO ₂ in the target material

ρ ₂ : Density of SnO ₂ (6.95g/cm ³ )

C ₃ : Mass % of SiO ₂ in the target material

ρ ₃ : Density of SiO ₂ (2.20g/cm ³ )

In addition, the mass % of In ₂ O ₃ , the mass % of SnO ₂ , and the mass % of SiO ₂ can be determined based on the analysis results of each element of the target material obtained by ICP-OES analysis.

Regarding the deviation of the relative density, the rectangular target was divided into 3 vertical and 5 horizontal squares, and the relative density was measured for each divided measurement piece by the above method. Among the 15 measured relative densities, determine the relative density ρ _P of the measurement piece with the largest deviation from the relative density ρ _T of the target material before segmentation, and calculate it according to the formula ρ _T - ρ _P Relative density deviation.

5. Bulk resistance and Rmax/Rmin of sputtering target

The bulk resistance of the sputtering target is LORESTA (registered trademark)-GX MSP-T700 (series four-probe probe TYPE ESP) manufactured by MITSUBISHI CHEMICAL ANALYTECH. The probe is placed in contact with the surface of the processed sintered body to AUTO RANGE mode to test Certainly. The measurement locations were set to 15 locations approximately equally on the surface of the oxide sintered body (see FIG. 1 ), and the arithmetic mean value of each measured value was used as the volume resistance value of the sintered body.

The Rmax/Rmin of the sputtering target is calculated by taking the maximum bulk resistance value as Rmax and the minimum resistance value as Rmin among the bulk resistance values measured at the above 15 locations.

6. Vickers hardness of sputtering target material

Vickers hardness tester MHT-1 (machine manufacturer: MATSUZAWA SEIKI) is used and measured in accordance with JIS standard: JIS-R-1610: 2003 (hardness test method for precision ceramics).

Specifically, the cut surface obtained by cutting the oxide sintered body is ground in stages using sandpaper #180, #400, #800, #1000, and #2000, and finally polished and polished to a mirror surface, thereby producing into a measurement surface. In addition, the surface opposite to the observation surface from the measurement surface was polished using the above-mentioned sandpaper #180 so as to be parallel to the measurement surface. Using the above test piece, the hardness measurement method was carried out in accordance with JIS-R-1610:2003 (Hardness Test Method for Precision Ceramics) with a load of 1kgf.

7. Bending strength of sputtering target material

Measurement was performed using Autograph (registered trademark) AGS-500B (machine manufacturer: Shimadzu Corporation) and in accordance with JIS standard: JIS-R-1601 (Bending strength test method for precision ceramics). Specifically, a sample piece (total length 36 mm or more, width 4.0 mm, thickness 3.0 mm) cut from an oxide sintered body was used, and the 3-point bending strength of JIS-R-1601 (bending strength test method of precision ceramics) was used. The measurement method is used to measure.

8. Evaluation of abnormal discharge of sputtering targets

DC sputtering was performed under the following conditions using a DC magnetron sputtering device (high-speed sputtering device manufactured by Vacuum Instrument Industry Co., Ltd.), an exhaust-type cryogenic pump, and a rotary pump.

Ultimate vacuum degree: 3×10 ^-6 [Pa]

Sputtering pressure: 0.65[Pa]

Argon gas flow: 50[cc]

Oxygen flow: 2.0[cc]

Input power: 0.72[kW]

Time: 24 hours

The number of abnormal discharge occurrences was evaluated in the following manner using an arc counter (model: μArc Moniter MAM Genesis MAM data collector Ver.2.02 (manufactured by LANDMARK TECHNOLOGY)).

A: Less

B: Slightly more

C: More

[Examples 1~5]

In ₂ O ₃ powder, SnO ₂ powder, and SiO ₂ powder were prepared at the ratios shown in Table 1, and then put into a resin tank and mixed with a dry ball mill for 21 hours to prepare a raw material composition. Furthermore, when performing dry ball milling, zirconia balls are used as the medium.

Then, the medium and the raw material composition were classified by sieving, and 8.0 mass % of polyvinyl alcohol diluted with pure water to 5.5 mass % with respect to the total mass of the raw material composition was added to the raw material composition, and then , add 0.5 mass% stearic acid.

The above-mentioned raw material composition was mixed using a mortar until the additives were combined, and passed through a 5.5-mesh sieve. The obtained raw material composition was temporarily pressurized by the cold pressing method under conditions of 200 kg/cm ² , and the obtained temporary formed body was pulverized using a mortar.

The powder obtained by crushing was filled into a pressing mold, and molded by a cold pressing method at a pressurizing pressure of 600 kg/cm ² for 60 seconds to obtain a molded body.

The obtained molded body was put into a calcining furnace, oxygen was flowed into the furnace at 1 L/h, and it was calcined at 1480° C. for 16 hours. Thereafter, cooling was performed at a cooling rate of 50°C/h. The obtained oxide sintered body was subjected to plane cutting using a #170 grindstone to produce a sputtering target with a surface Ra of 1.0 μm. The sputtering target is rectangular, with the long side dimension being 490mm and the short side dimension being 370mm.

The cracking of the target material was confirmed visually, and each characteristic was evaluated according to the above-mentioned evaluation method. In addition, a Φ4-inch sample was cut out from the target material and evaluated for abnormal discharge. The results are shown in Table 1.

[Example 6]

Except that the calcining temperature was changed from 1480°C to 1500°C, a 490mm×370mm rectangular sputtering target was manufactured using the same manufacturing method as in Example 3.

The cracking of the target material was confirmed visually, and each characteristic was evaluated according to the above-mentioned evaluation method. In addition, a Φ4-inch sample was cut out from the target material and evaluated for abnormal discharge. The results are shown in Table 1.

[Example 7]

Except that no stearic acid was added, a 490mm×370mm rectangular sputtering target was manufactured using the same manufacturing method as in Example 3.

The cracking of the target material was confirmed visually, and each characteristic was evaluated according to the above-mentioned evaluation method. In addition, a Φ4-inch sample was cut out from the target material and evaluated for abnormal discharge. The results are shown in Table 1.

[Comparative example 1]

Except that the calcining temperature was changed from 1480°C to 1550°C, a 490mm×370mm rectangular sputtering target was manufactured using the same manufacturing method as in Example 3.

In this comparative example, the target material was cracked, so a Φ4-inch sample was cut out from the unbroken part for evaluation of abnormal discharge. In addition, the cracking of the target material was confirmed visually, and each characteristic was evaluated according to the above-mentioned evaluation method. The results are shown in Table 1.

[Comparative example 2]

Except that the calcining temperature was changed from 1480°C to 1550°C, a 490mm×370mm rectangular sputtering target was manufactured using the same manufacturing method as in Example 4.

In this comparative example, the target material was cracked, so a Φ4-inch sample was cut out from the unbroken part for evaluation of abnormal discharge. In addition, the cracking of the target material was confirmed visually, and each characteristic was evaluated according to the above-mentioned evaluation method. The results are shown in Table 1.

It is clear from Table 1 that in Examples 1-5, the In, Sn and Si contents are within the range of the present invention, and the area ratio of the SiO ₂ phase observed in the cross section of the oxide sintered body constituting the target material is less than 3%, so the number of abnormal discharges is less, and good DC sputtering can be achieved. However, compared with Examples 1-5, the calcination temperature of Example 6 is as high as 1500°C and the area ratio of the SiO ₂ phase is as high as 3%, so a slight abnormal discharge was observed during DC sputtering.

In Example 7, since stearic acid was not added to the raw material composition, each element source was included in the raw material composition in a relatively uneven and dispersed state, and the uniformity and density of the raw material composition were reduced. Therefore, some abnormal discharge was observed in DC sputtering. Furthermore, in Table 1, the relative density difference, Rmax/Rmin and flexural strength are reduced compared to Examples 1-5, which shows that the uniformity and density of the raw material composition are reduced.

On the other hand, in Comparative Examples 1 and 2, the area ratio of the SiO ₂ phase observed in the cross section of the oxide sintered body constituting the target exceeded 3%. Therefore, it was found that abnormal discharge occurred frequently and good DC sputtering could not be achieved. plated.

Furthermore, the same manufacturing method as in Examples 1 to 7 and Comparative Examples 1 to 2 was used to manufacture targets with the following sizes. As a result, no cracks were found in any of the targets in the manufacturing methods of Examples 1 to 7. In the manufacturing methods of Comparative Examples 1 and 2, cracks were observed in all target materials.

‧400mm×500mm=200000mm ²

‧350mm×450mm=157500mm ²

‧300mm×400mm=120000mm ²

‧250mm×350mm=87500mm ²

‧200mm×350mm=70000mm ²

[Industrial availability]

According to the present invention, it is possible to provide an oxide sintered body suitable for a sputtering target in which the occurrence of abnormal discharge is further suppressed, and a manufacturing method thereof. Furthermore, according to the present invention, it is possible to provide a sputtering target in which the occurrence of abnormal discharge is further suppressed.

If the oxide sintered body of the present invention is used for sputtering, compared with the case of using the conventional oxide sintered body, abnormal discharge during sputtering can be suppressed and film formation can be performed. Therefore, many problems can be suppressed. The generation of defective products can even reduce the generation of waste. That is, the energy cost of processing such waste can be reduced. This can achieve sustainable management and effective utilization of natural resources, as well as decarbonization (carbon neutrality).

Claims (13)

An oxide sintered body containing indium (In) element, tin (Sn) element and silicon (Si) element, and the Sn content is 50 mass % or more and 70 mass % or less in terms of SnO ₂ , and the Si content is 50 mass % or more and 70 mass % or less in terms of SiO ₂ Converted to 3% by mass or more and 15% by mass or less, and the remainder includes indium, oxygen, and unavoidable impurities, the area ratio of the SiO ₂ phase observed in the cross section of the above-mentioned oxide sintered body is 3% or less. For example, the relative density of the oxide sintered body of claim 1 is above 100%. The oxide sintered body of Claim 1 or 2, wherein the relative density of the above-mentioned oxide sintered body is ρ _T , and when the above-mentioned oxide sintered body is divided into a plurality of measuring pieces, the relative density of the measuring pieces is When the relative density whose median value is farthest from the above relative density ρ _T is set to ρ _P , the difference between the relative densities defined by ρ _T - ρ _P is less than ±1%. For example, the oxide sintered body of claim 1 or 2, wherein the maximum body resistance value among the body resistance values measured at a plurality of locations on the surface of the above-mentioned oxide sintered body is set as Rmax, and the minimum resistance value is set as Rmin. When, the value of Rmax/Rmin is above 1.0 and below 2.0. The oxide sintered body of claim 1 or 2, wherein the area ratio of the SiO ₂ phase observed in the cross section of the oxide sintered body is 0.1% or more and 2.8% or less. For example, _the oxide sintered body of Claim 1 or 2, wherein the Sn content is 55 mass % or more and 65 mass % or less in terms of SnO ₂ , and the Si content is 6 mass % or more and 12 mass % or less in terms of SiO 2 . For example, the Vickers hardness of the oxide sintered body of claim 1 or 2 is above 900 HV1. A sputtering target material comprising the oxide sintered body of claim 1 or 2. For example, if the sputtering target material in claim 8 is used, the area of its sputtering surface is more than 70000 ^mm2 . A method for manufacturing an oxide sintered body, which includes the following steps: preparing a raw material composition including an indium (In) element source, a tin (Sn) element source, and a silicon (Si) element source, The above raw material composition is molded to obtain a molded body, Calcining the above shaped body; and The above-mentioned molded body is calcined at a temperature of not less than 1450°C and not more than 1500°C for not less than 4 hours and not more than 20 hours. The manufacturing method of Claim 10, wherein the above-mentioned shaped body is calcined at a temperature of not less than 1460°C and not more than 1490°C. The manufacturing method of claim 10 or 11, wherein the raw material composition contains fatty acid. The production method of claim 12, wherein the fatty acid is a saturated fatty acid with a carbon number of 10 to 22.

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