JP4457669B2 - Sputtering target and manufacturing method thereof - Google Patents

Description

  The present invention relates to a sputtering target for forming a thin film suitable for a transparent conductive film, particularly a transparent conductive film for a touch panel.

  With the development of information society in recent years, computers are spreading rapidly. For this reason, attention is being paid to displays and input devices as man-machine interfaces. Conventionally, as a method for inputting to a computer or the like, CUI (Character based User Interface) mainly using keyboard input has been mainly used, but recently, GUI (Graphical User Interface) using a pointing input device is becoming mainstream.

  Examples of pointing input devices include a mouse, a trackball, and a touch panel. In particular, the touch panel integrated with the display has a feature that input can be performed directly with a finger or a dedicated pen on the panel. For this reason, since the display and the input device can be integrated and the system can be reduced in size, it is often used in PDA (Personal Digital Assistant), HPC (Handheld PC) and the like. The touch panel market is expanding with the spread of these mobile devices.

  Touch panel systems are broadly classified into (1) resistive film system, (2) optical system, (3) electrostatic capacity system, (4) ultrasonic system, and (5) pressure system. Among these, the resistive film method has features such as thinness, lightness, resistance to cracking, and low cost, and is the most suitable touch panel for portable information terminals.

  A resistive touch panel has a structure in which an upper electrode formed of a transparent conductive film on the surface of a film such as plastic and a lower electrode made of a glass substrate or film on which a similar transparent conductive film is formed face each other through a spacer. ing. By touching the upper electrode with a finger or a pen, the upper electrode comes into contact with the lower electrode, and the touched location is detected from the current value at that time.

  In such a touch panel, a transparent conductive film having a relatively high sheet resistance (500 to 1000Ω / □) and a very high transmittance is required in order to improve the position accuracy when detecting the touch position.

  If the most common ITO (Tin doped Indium Oxide) thin film is used as the transparent conductive film to obtain a sheet resistance of 500 to 1000Ω / □ as described above, the film thickness becomes 2 to 4 nm. Such a thin film is formed in an island shape on the substrate and becomes a discontinuous film. Therefore, the resistance value on the substrate becomes non-uniform and is not suitable for a resistive film type touch panel.

  On the other hand, when the sheet resistance is controlled not by the film thickness but by the resistivity (volume resistivity) of the thin film, for example, in order to obtain the above sheet resistance at a film thickness of about 10 nm, the resistivity is about 500 to 1000 μΩ · cm. A membrane is suitable. However, if such a film is made using ITO, a region where the resistivity changes greatly with respect to the oxygen partial pressure has to be selected as a film forming condition. is not.

  A transparent conductive film in which ZnO is doped with Al instead of the ITO film has a resistance value of about 500 μΩ · cm, but this is also not preferable because the durability of the film is inferior.

  For this reason, a transparent conductive film capable of industrially producing a value of about 500 to 1000 μΩ · cm as a resistivity, which has a high transmittance and can be finely processed like ITO. It was desired.

  In order to solve such a problem, a method of adding magnesium to ITO has been reported (for example, see Patent Document 1). This magnesium-containing ITO film has a feature that the resistivity of the thin film is high, a sheet resistance of 500 to 1000 μΩ · cm can be secured with a film thickness of about 10 nm, and weather resistance (heat resistance and humidity resistance) is superior to the ITO film. Had.

  In the touch panel, in order to accurately detect the positions touched one after another, it is necessary to immediately separate the substrates facing each other at the touched portion. For this purpose, it is known that it is effective to form surface protrusions of 20 nm or more on the surface of one of the opposing glass substrate or film (for example, see Non-Patent Document 1). Since the surface of the magnesium-containing ITO film has no projections of 20 nm or more and is a flat film, when used as a touch panel, the part of the film touched by the pen or finger contacts the glass substrate or film on the opposite side A new problem has arisen that it is impossible to leave.

JP 2001-151572 A

10th Flat Panel Display Special Technology Exhibition Parts and Materials Course Special Technology Seminar Text P40, (2000)

  The subject of this invention is providing the sputtering target which can form 20 nm or more protrusion on the surface of the magnesium containing ITO thin film excellent in weather resistance as a touch panel.

  The present inventors diligently studied a method for forming protrusions of 20 nm or more on the surface of a magnesium-containing ITO thin film. As a result, the inventors have found that the surface state of the magnesium-containing ITO thin film depends on the amount of oxygen gas introduced as a reactive gas during sputtering, and that protrusions are easily formed on the film surface by reducing the amount of oxygen. However, since the resistivity of the thin film depends on the amount of oxygen, the resistivity of the obtained film changes when the conventional magnesium-containing ITO target is used to reduce the amount of oxygen gas introduced. Therefore, the present inventors have further studied, and can contain protrusions of 20 nm or more on the surface of the resulting film by containing a large amount of oxygen in the target and reducing the amount of oxygen introduced into the chamber during sputtering. I found.

In such a target, an oxidizing gas is introduced into the firing furnace from at least 800 ° C. at the time of temperature increase to at least 800 ° C. at the time of temperature decrease in the firing process, and the temperature decrease rate is made slower than 50 ° C./hour. Accordingly, by incorporation of oxygen in the pseudo anion site _in 2 _{O 3} phase bixbyite structure is changed to _in 4 _Sn 3 _{O 12} phase fluorite structure, the _in 4 _Sn 3 _{O 12} phase of the fluorite structure ( integrated intensity of X-ray diffraction peak of 220) plane, obtained by such a the bixbite structure in ₂ O ₃ phase (211) 40% of the integral intensity of X-ray diffraction peaks of the surface above it The present invention has been completed.

That is, the present invention substantially consists of indium, tin, magnesium, and oxygen, and the (220) plane X-ray diffraction peak of the fluorite-structured In ₄ Sn ₃ O ₁₂ phase that is an intermediate compound of indium oxide and tin oxide. In particular, the present invention relates to a sputtering target made of a sintered body, characterized in that the integrated intensity is 40% or more of the integrated intensity of the X-ray diffraction peak of the (211) plane of the In ₂ O ₃ phase of the bixbite structure.

  Hereinafter, the present invention will be described in detail.

  A sputtering target for realizing the present invention can be manufactured, for example, by the following method.

  A target that uses a sintered body substantially made of indium, tin, magnesium, and oxygen is used. By doing so, high resistivity and weather resistance can be obtained. The density of the sintered body is preferably 98% or more in terms of relative density from the viewpoint of discharge stability, and such a sintered body can be produced, for example, by the following method.

  As the raw material powder, indium oxide, tin oxide, magnesium oxide, magnesium hydroxide, or the like can be used. Magnesium oxide can be used as the magnesium source. In this case, magnesium oxide in the molded body tends to react with moisture in the air to form magnesium hydroxide. Since the reaction from magnesium oxide to magnesium hydroxide is accompanied by volume expansion, the molded body is stressed and causes cracks. Use of magnesium hydroxide powder is preferable because it does not react with moisture in the air, and cracks do not occur in the molded body even in a situation where the molded body is exposed to air during the manufacturing process.

  Hereinafter, although the case where magnesium hydroxide is used is described, the effect of the present invention can be obtained even when magnesium oxide is used.

  Each powder to be used is preferably a powder having a maximum secondary particle size of 1 μm or less and an average particle size of 0.4 μm or less. The average particle size in the present invention means the particle size of the powder corresponding to 50% of the volume-based cumulative distribution of particle size. This makes it easier to obtain a high-density sintered body.

  Next, although these powders are mixed, it is preferable to perform this mixing process in two stages. Specifically, first, a predetermined amount of indium oxide powder, tin oxide powder, and magnesium hydroxide powder are weighed and mixed using, for example, a shaker mixer or the like without using a medium such as a ball. In this mixing, the degree of mixing of the powder is increased and the tertiary particles formed by aggregation of the secondary particles are loosened. Here, when a medium such as a nylon ball is used and mixed using, for example, a ball mill, the powder is not sufficiently loosened, and the powder is compacted in an insufficiently mixed state, which is not preferable. The mixing time in this step is preferably 10 minutes or more, and although there is no particular upper limit, it is sufficient to carry out for 1 hour.

  Subsequently, the mixed powder is put into a pot of a ball mill together with a medium such as a nylon ball to perform second mixing and compaction of the powder. The mixing time in this step is preferably 10 to 30 hours. Since the compacted powder obtained in this way may be aggregated into coarse particles, the obtained mixed powder is passed through a sieve having an opening of about 300 μm to remove aggregated particles that do not pass through the sieve. . By such a mixing method, the structure of the sintered body is 10 to 20 atomic% of tin, 0.5 atomic% or less of magnesium, the remainder is composed of indium and oxygen, 5 atomic% or less of tin, and 0 of magnesium. It is possible to produce a target composed only of particles of .8 to 1.5 atomic% and the balance being indium and oxygen. And by setting it as such a structure, the abnormal discharge during sputtering can be suppressed.

  The amount of tin oxide mixed is preferably 1.9 to 14% in terms of an atomic ratio of Sn / (Sn + In). More preferably, it is 4 to 11%. The mixing amount of the magnesium hydroxide powder is preferably 0.1 to 20% in terms of the atomic ratio of Mg / (In + Sn + Mg). More preferably, it is 0.3-10%, More preferably, it is 0.5-5%. If the amount of magnesium hydroxide powder added is less than the above range, the etching characteristics and durability may be inferior, and if it exceeds the above range, the resistivity may be too high.

Next, the obtained mixed powder is molded by a molding method such as a press method or a casting method to produce a molded body. In the case of producing a molded body by press molding, the mixed powder is filled into a mold having a predetermined size, and then pressed at a pressure of 100 to 500 kg / cm ² using a press machine to obtain a molded body. At this time, a binder such as PVA may be added as necessary.

  On the other hand, in the case of producing a molded body by a casting method, the raw material powder is mixed with water, a binder and a dispersing agent to form a slurry, and the slurry having a viscosity of 50 to 5000 centipoise thus obtained is formed into a desired water-absorbing property. A molded body is prepared by pouring into a porous mold.

The molded body thus obtained is treated by cold isostatic pressing (CIP) as necessary. At this time, since the pressure of the CIP to obtain a sufficient compaction effect 1 ton / cm ² or more, it is desirable that preferably is 2~5ton / cm ^2.

  When molding is performed by a casting method, a drying process and a debinding process are performed at a temperature of 300 to 500 ° C. for about 5 to 20 hours in order to remove moisture and organic substances such as a binder remaining in the molded body after CIP. It is preferable to apply. Even when the molding is performed by the press method, it is preferable to perform the same debinding process when a binder is used during the molding.

  Next, the molded body thus obtained is fired. The temperature raising rate is not particularly limited, but is preferably 10 to 400 ° C./hour from the viewpoint of shortening the sintering time and preventing cracking. When raising the temperature, at least from a temperature of 800 ° C., the ratio of the oxidizing gas flow rate (L / min) to the charged weight (kg) of the molded body (charged weight / oxidizing gas flow rate) is set in the furnace. , 1.0 or less. Preferably, it introduce | transduces at 600 degreeC or more, More preferably, it introduces at 400 degreeC or more. Below this temperature, the molded body does not sinter, and therefore, even if an oxidizing gas is introduced, the sintered body does not change in characteristics. As the oxidizing gas, oxygen is representative, but oxygen added with ozone may also be used.

  The sintering temperature is 1450 ° C. or higher and lower than 1650 ° C., preferably 1500 to 1600 ° C. The sintering time is 5 hours or more, preferably 5 to 30 hours in order to obtain a sufficient density increasing effect.

  When the temperature is lowered, the temperature is usually lowered at a rate of about 100 ° C./hour in consideration of productivity, but in the present invention, it is less than 50 ° C./hour, preferably 30 ° C./hour or less, more preferably 10 ° C./hour. Lower the temperature slowly at the following speed.

  In this temperature lowering step, the oxidizing gas having the above flow rate is kept flowing until at least the inside of the furnace reaches 800 ° C. or lower. Preferably, the flow is continued to 600 ° C. or lower, more preferably 400 ° C. or lower. Below this temperature, even if an oxidizing gas is introduced, the characteristic does not change with respect to the amount of oxygen in the sintered body after firing.

Oxygen is efficiently taken into the sintered body by controlling the temperature lowering rate and the process of continuously flowing the oxidizing gas, and the X of the (220) plane of the In ₄ Sn ₃ O ₁₂ phase having a fluorite structure suitable for the present invention. A sintered body in which the integrated intensity of the line diffraction peak is 40% or more of the integrated intensity of the X-ray diffraction peak of the (211) plane of the In ₂ O ₃ phase of the bixbite structure can be obtained.

The X-ray diffraction peak of the (220) plane of the In ₄ Sn ₃ O ₁₂ phase of the present invention appears in the vicinity of 2θ = 50.7 ° (d value is 1.797) when Cu is used as the X-ray source. It is a peak. Further, the X-ray diffraction peak of the (211) plane of the In ₂ O ₃ phase appears in the vicinity of 2θ = 21.4 ° (d value is 4.151) when the same X-ray diffraction apparatus as described above is used. It is a peak. In the present invention, a sintered body subjected to polishing is used as a measurement sample, a CuX ray source, a graphite monochromator is used, and background cancellation is not performed on an XRD profile obtained by a continuous scan of θ-2θ, The influence of Kα ₂ was determined by simply using the Rachinger method and removing it as (Kα ₂ / Kα ₁ ) = 0.5 and then simply calculating the peak height ratio.

  The higher the sintered density (relative density), the better, preferably 95.0% or more. More preferably, it is 98.0% or more, and particularly preferably 99.0% or more.

Note that the relative density in the present invention (D) _shows the relative value with respect to In ₂ O 3, SnO ₂ and the theoretical density determined from the true density of the arithmetic mean of MgO (d). The theoretical density determined from the arithmetic mean (d), in the sintered body _composition, In ₂ O 3, SnO ₂ and mixtures of MgO powder (g), respectively a, b, when the c, _In 2 O ₃ , SnO ₂ and MgO true densities of 7.18, 6.95, 3.58 (g / cm ³ ) and d = (a + b + c) / ((a / 7.18) + (b / 6. 95) + (c / 3.58)). Then, when the measured density of the sintered body is d ₁ , the relative density D (%) is obtained by the formula: D = (d ₁ / d) × 100.

  When magnesium hydroxide is used as the raw material powder, the magnesium hydroxide contained in the added magnesium hydroxide is all converted to magnesium oxide, and calculated by converting the added weight of magnesium hydroxide into the added weight of magnesium oxide. do it.

  The sintered body thus obtained is shaped into a predetermined shape to obtain a sputtering target. In addition, you may process and polish as needed, and you may join on a backing plate which consists of oxygen-free copper etc. using indium solder etc.

  In sputtering, an oxygen gas or the like is added as necessary to an inert gas such as argon as a sputtering gas, and the gas pressure is usually controlled to 2 to 10 mTorr. As a power application method for sputtering, DC, RF, or a combination thereof can be used.

When the target of the present invention is used, the amount of oxygen introduced in addition to the above inert gas can be reduced, so that many protrusions are formed on the surface of the thin film. The protrusions referred to here are convex portions formed on the surface of the ITO thin film and having a width of about 30 to 100 nm and a height of about 20 to 100 nm. If there are 5 or more such protrusions per 1 μm ^2, it is preferable to prevent the touch panel from sticking.

  Further, these protrusions increase due to a decrease in oxygen partial pressure during film formation, and the height thereof increases. When the film is formed using only Ar, the number is maximum and maximum.

  In addition, the sputtering target according to the present invention is also effective in a target to which a fourth element is added for the purpose of providing an additional function. Examples of the fourth element include Al, Si, Ti, Zn, Ga, Ge, Y, Zr, Nb, Hf, and Ta. The addition amount of these elements is not particularly limited, but it does not deteriorate the excellent electro-optical characteristics of ITO. Therefore, (total of oxides of fourth element) / (total of oxides of ITO + fourth element) ) / 100, preferably exceeding 0% and not more than 20% (weight ratio).

  After the thin film formed on the substrate is etched into a desired pattern as necessary, it can constitute a device such as a touch panel.

As described above, according to the present invention, it is possible to obtain a transparent conductive film suitable for a touch panel having 5 or more protrusions of 20 nm or more per 1 μm ² and satisfying resistivity, heat resistance characteristics, and moisture resistance characteristics.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these.

Example 1
450 parts by weight of indium oxide powder (average particle size 0.4 μm), 50 parts by weight of tin oxide powder (average particle size 0.3 μm) and 0.25 parts by weight of magnesium hydroxide powder (average particle size 0.4 μm) (Mg / (In + Sn + Mg) = 0.12 atomic%) was mixed for 20 minutes using a shaker mixer.

  Next, the obtained mixed powder is put into a polyethylene pot together with nylon balls, mixed and compacted by a dry ball mill for 72 hours to prepare a mixed powder, and then the obtained powder is passed through a sieve having an opening of 300 μm to obtain coarse particles. Was removed.

The mixed powder thus obtained was put in a mold and pressed at a pressure of 300 kg / cm ² to obtain a molded body of 150 mm × 300 mm × 10 mmt. These molded bodies were subjected to CIP treatment at a pressure of 3 ton / cm ² .

Next, the obtained molded body was placed in a pure oxygen atmosphere sintering furnace and fired under the following conditions.
(Sintering conditions)
Temperature increase rate: 25 ° C./hour, sintering temperature: 1500 ° C., sintering time: 6 hours, temperature decrease rate: 10 ° C./hour, atmosphere: pure oxygen gas in the furnace from 800 ° C. during temperature increase to 400 ° C. during temperature decrease Introduced at (charged weight (kg) / oxygen flow rate (L / min)) = 0.8 The sintered density of the obtained sintered body was examined by Archimedes method and the crystal structure was examined by XRD.
(XRD measurement conditions)
X-ray source: Cukα, diffraction peak due to Kα1 only, power: 50 kV, 200 mA
Measurement method: 2θ / θ, continuous scan, scan speed: 2 degrees / minute (scan range (2θ): 20 to 60 degrees)
The measurement results are summarized in Table 1.

  Further, the composition ratio of each particle was measured using EPMA. Particles composed of 13 to 17 atomic% tin, 0 to 0.3 atomic% magnesium, 25 atomic% indium, and the balance oxygen, tin 2-3 atomic%, magnesium 0.9-1. Particles composed of 3 atomic%, indium from 36 to 39 atomic% and the balance consisting of oxygen were observed.

The obtained sintered body was bonded to a backing plate made of oxygen-free copper using indium solder. A thin film was formed using this target.
(Sputtering conditions)
Sputtering method: DC magnetron, substrate temperature: 200 ° C., sputtering gas: Ar only, gas pressure: 5 mTorr, DC power density: 2.3 W / cm ²
Table 1 summarizes the resistivity of the film obtained and the number of protrusions of 20 nm or more per 1 μm ² . The number of protrusions was determined by counting from images obtained using AFM: Nano-Scope IIIa manufactured by Digital Instruments.

Next, a heat resistance test and a moisture resistance test of the obtained thin film were performed under the following conditions, and the rate of change in resistivity was examined. In addition, the change rate of the resistivity was obtained by (Resistivity after test−Resistivity before test) × 100 / Resistivity before test.
(Heat resistance test)
Atmosphere: In air, temperature: 250 ° C., retention time: 30 minutes (moisture resistance test)
Temperature: 60 ° C., humidity 90% RH, retention time: 500 hours The results are summarized in Table 1. A film having good results over all of the resistivity, the number of surface protrusions, heat resistance and moisture resistance could be obtained.

Example 2
Example 1 except that the mixing ratio of the powder was 450 parts by weight of indium oxide powder, 50 parts by weight of tin oxide powder and 1.05 parts by weight of magnesium hydroxide powder (Mg / (In + Sn + Mg) = 0.52 atomic%). A magnesium-containing ITO target was prepared by the same method.

  The sintered density of the obtained sintered body was examined by the Archimedes method, and the crystal structure was examined by XRD. The results are summarized in Table 1.

  Using the obtained target, a film was formed by the same method as in Example 1, and the resistivity and surface state were examined. The results are summarized in Table 1.

  Next, a heat resistance test and a moisture resistance test were performed under the same conditions as in Example 1. The results are summarized in Table 1. Films with good results could be obtained over all of resistivity, surface condition, heat resistance test and moisture resistance test.

Example 3
Example 1 except that the mixing ratio of the powder was 450 parts by weight of indium oxide powder, 50 parts by weight of tin oxide powder and 10.85 parts by weight of magnesium hydroxide powder (Mg / (In + Sn + Mg) = 4.7 atomic%). A magnesium-containing ITO target was prepared by the same method.

  The sintered density of the obtained sintered body was examined by the Archimedes method, and the crystal structure was examined by XRD. The results are summarized in Table 1.

  Using the obtained target, a film was formed by the same method as in Example 1, and the resistivity and surface state were examined. The results are summarized in Table 1.

  Next, a heat resistance test and a moisture resistance test were performed under the same conditions as in Example 1. The results are summarized in Table 1. Films with good results could be obtained over all of resistivity, surface condition, heat resistance test and moisture resistance test.

Example 4
Example 1 except that the mixing ratio of the powder was 450 parts by weight of indium oxide powder, 50 parts by weight of tin oxide powder and 22.42 parts by weight of magnesium hydroxide powder (Mg / (In + Sn + Mg) = 9.7 atomic%). A magnesium-containing ITO target was prepared by the same method.

  The sintered density of the obtained sintered body was examined by the Archimedes method, and the crystal structure was examined by XRD. The results are summarized in Table 1.

  Using the obtained target, a film was formed by the same method as in Example 1, and the resistivity and surface state were examined. The results are summarized in Table 1.

  Next, a heat resistance test and a moisture resistance test were performed under the same conditions as in Example 1. The results are summarized in Table 1. Films with good results could be obtained over all of resistivity, surface condition, heat resistance test and moisture resistance test.

Example 5
Example 1 except that the mixing ratio of the powder was 450 parts by weight of indium oxide powder, 50 parts by weight of tin oxide powder and 50.63 parts by weight of magnesium hydroxide powder (Mg / (In + Sn + Mg) = 19.5 atomic%). A magnesium-containing ITO target was prepared by the same method.

  The sintered density of the obtained sintered body was examined by the Archimedes method, and the crystal structure was examined by XRD. The results are summarized in Table 1.

  Using the obtained target, a film was formed by the same method as in Example 1, and the resistivity and surface state were examined. The results are summarized in Table 1.

  Next, a heat resistance test and a moisture resistance test were performed under the same conditions as in Example 1. The results are summarized in Table 1. Films with good results could be obtained over all of resistivity, surface condition, heat resistance test and moisture resistance test.

Example 6
A magnesium-containing ITO target was produced in the same manner as in Example 2 except that the temperature lowering rate in the firing step was 30 ° C./hour.

  The sintered density of the obtained sintered body was examined by the Archimedes method, and the crystal structure was examined by XRD. The results are summarized in Table 1.

  Using the obtained target, a film was formed by the same method as in Example 1, and the resistivity and surface state were examined. The results are summarized in Table 1.

  Next, a heat resistance test and a moisture resistance test were performed under the same conditions as in Example 1. The results are summarized in Table 1. Films with good results could be obtained over all of resistivity, surface condition, heat resistance test and moisture resistance test.

Comparative Example 1
A magnesium-containing ITO target was prepared in the same manner as in Example 3 except that the temperature lowering rate was 80 ° C./hour in the firing step.

  The sintered density of the obtained sintered body was examined by the Archimedes method, and the crystal structure was examined by XRD. The results are summarized in Table 1.

  A film was formed by the same method as in Example 1 except that the oxygen partial pressure during film formation was changed to 0.2% using the obtained target, and the resistivity and surface state were examined. The results are summarized in Table 1.

  Next, a heat resistance test and a moisture resistance test were performed under the same conditions as in Example 1. The results are summarized in Table 1. In the resistivity and weather resistance, good results were obtained, but the film was flat without protrusions.

Claims (5)

Lee indium, tin, made of magnesium and oxygen, the integrated intensity of the X-ray diffraction peak of In ₄ Sn ₃ O ₁₂ phase (220) plane of the fluorite structure is an intermediate compound of indium oxide and tin oxide is, bixbyite structure A sputtering target comprising a sintered body that is 40% or more of the integrated intensity of the X-ray diffraction peak of the (211) plane of the In ₂ O ₃ phase. 2. The sputtering target according to claim 1, wherein the sputtering target is made of a sintered body containing magnesium at a ratio of 0.1 to 20.0% in terms of an atomic ratio of Mg / (In + Sn + Mg). The structure of the sintered body is 10 to 20 atom% tin, 0.5 atom% or less magnesium, the balance is indium and oxygen, tin is 5 atom% or less, and magnesium is 0.8 to 1.5 atom. The sputtering target according to claim 1, wherein the balance is composed of particles made of indium and oxygen. In a method for producing a sputtering target, comprising forming a powder comprising indium oxide, tin oxide and magnesium oxide or magnesium hydroxide and then firing the molded body in an oxidizing atmosphere to obtain a magnesium-containing ITO sintered body. During firing to obtain the magnesium-containing ITO sintered body, an oxidizing gas is introduced into the firing furnace from at least 800 ° C. at the time of temperature rise to at least 800 ° C. at the time of temperature fall, and the temperature drop rate is 50 ° C./hour. The manufacturing method of the sputtering target characterized by making it slower. The method for producing a sputtering target according to claim 4, wherein indium oxide powder, tin oxide powder, or magnesium hydroxide powder is used as a raw material.