KR100455280B1 - Method of preparing indium tin oxide(ITO) - Google Patents

Abstract

The present invention comprises the steps of (a) injecting a precipitant into the In-containing salt solution and Sn-containing salt solution to form a precipitate; (b) aging the precipitates obtained from step (a), respectively; (c) filtering the resultant obtained from step (b), and then dispersing with a dispersant; And (d) drying the resultant obtained from step (c), respectively, and heat-treating the resultant to obtain In ₂ O ₃ powder and SnO ₂ powder, respectively, and mixing them. Indium Tin Oxide (ITO), comprising: It provides a method of manufacturing). According to the present invention, the primary particle size of the ITO powder is refined to 80 nm or less, and precipitation conditions and aging treatments such as concentration, pH, and temperature of the In-containing salt solution and the Sn-containing salt solution are prepared in the preparation of In ₂ O ₃ and SnO ₂ . By controlling the conditions within an appropriate range, the degree of Sn substitution in the cubic structure of In ₂ O ₃ during sintering is increased to prevent the formation of pores during densification, and the alcohol dispersion before drying after filtration during preparation of In ₂ O ₃ powder and SnO ₂ powder By the treatment, a densified ITO sintered body can be obtained.

Description

Method of preparing indium tin oxide (ITO) {Method of preparing indium tin oxide (ITO)}

The present invention relates to a method for producing indium tin oxide (ITO), and more particularly to a method for producing ITO powder for high density ITO target.

ITO transparent conductive film that is transparent and has high electric conductivity due to its large light transmittance in visible light is widely used in flat electrodes such as liquid crystal display, plasma display panel, field emission display device, electroluminescent device, transparent electrode such as solar cell and transparent heating wire. Is used. As the material for forming the transparent electrode, SnO ₂ , ZnO, or the like is used, and indium tin oxide (ITO) in which SnO ₂ is added to In ₂ O ₃ is widely used.

ITO is a transparent electrically insulating material in the visible wavelength region if the stoichiometric composition is correct, but free electrons are generated in the crystal when it is out of the stoichiometric composition due to lack of oxygen, thereby making it transparent and conductive in the visible wavelength region. The ITO film is a crystalline transparent film produced by a vapor deposition method, a sputtering method, or the like, and is used as a liquid crystal display electrode in a wide range from a high resistance region (over 200 Ω /?) To a low resistance region (10 Ω / □). This ITO thin film is manufactured by various thin film deposition methods. In the case of flat panel displays, the sputtering method is most widely used because a large area uniform thin film is required. In order to use this sputtering method, a high-density ITO sintered body is required and many developments have been made for this.

Recently, in order to increase the display screen of a flat panel display device and to increase the clarity of the screen, an ITO film having a low resistance is required. To achieve this, an ITO target with a high sintered density of at least 98% was required. In order to manufacture such a high density ITO target, it is necessary to establish a fine ITO powder production, molding and sintering technology.

Looking at the development of the ITO target, the initial dependence on the molding and sintering technology such as hot isostatic pressing (HIP), but gradually advances in powder manufacturing technology, the atmospheric pressure sintering using CIP (cold isostatic pressing) is possible. This atmospheric sintering is possible due to the improved powder manufacturing process. In addition, the refinement of the powder manufacturing process enabled the refinement of the powder, enabling the primary particle size to 100 nm or less. In the powder manufacturing process, an electrolysis method, a precipitation method, a spray method, or the like is used.

According to U.S. Patent No. 5,700,419, Japanese Laid-Open Patent Publication No. Hei 6-1918416, Hei 10-1821150, an ITO powder was prepared by focusing on miniaturization of particles using the precipitation method, and U.S. Patent No. 5,866,493 was crystallized. The high density ITO powder was prepared under normal pressure and oxygen atmosphere sintering using the prepared ITO powder. And U. S. Patent No. 5,417, 816 prepared ITO powder by electrolysis, and produced high density ITO sintered body from this powder.

In view of the contents disclosed in the above patents, ITO powder production methods known to date are prepared by dissolving an In-Sn metal in an acid such as HNO ₃ , HCl, etc. to prepare ITO powder by coprecipitation method, In metal or In In ₂ O ₃ can be prepared from the containing salt, and it can be classified by the method of mixing SnO ₂ powder thereto. According to the above two methods, the size of the ITO primary powder was refined to 100 nm or less, and the sintered density was also improved. However, such fine powder has a high cohesive force between particles, which acts as another inhibitor of non-uniform densification and formation of pores during sintering.

The technical problem to be solved by the present invention is to provide a method for producing ITO that can obtain a high-density ITO sintered body by improving the dispersibility of the ITO particles by dispersing with alcohol while making the ITO powder finer by solving the above problems.

In order to achieve the above technical problem, in the present invention, the step of forming a precipitate by injecting a precipitant into the In-containing salt solution and Sn-containing salt solution, respectively;

(b) aging the precipitates obtained from step (a), respectively;

(c) filtering the resultant obtained from step (b), and then dispersing with a dispersant; And

(d) drying the resultant obtained from step (c), and then heat treating them to obtain In ₂ O ₃ powder and SnO ₂ powder, respectively, and mixing them; indium tin oxide (ITO), comprising: It provides a method of manufacturing.

The method for producing ITO according to the present invention may further include obtaining the ITO sintered body by sintering a mixture of In ₂ O ₃ powder and SnO ₂ powder obtained from the step (d) in an air atmosphere. Through this step, Sn is substituted in the In ₂ O ₃ powder cubic structure, thereby obtaining a higher density ITO sintered body.

In the present invention, the primary particle size of the ITO powder is refined to 80 nm or less, and the dispersibility of SnO ₂ , which has a decisive influence on the sintering of the ITO powder, is increased, thereby increasing the degree of SnO ₂ substitution in the In ₂ O ₃ upon sintering and porosity during densification It is characteristic to make the ITO sintered compact high by preventing the formation of. In addition, to improve the dispersibility of In ₂ O ₃ and SnO ₂ powder particles for forming ITO by dispersing with alcohol to prepare an ITO target having a high sintered density even in a normal atmosphere.

As described above, the particle shape of the SnO ₂ powder has a great influence on the sintering in the future, because the process of replacing Sn in the cubic structure of the In ₂ O ₃ powder occurs during the densification of the sintered body. And precipitation conditions, aging conditions and in the manufacture of a SnO ₂ powder is therefore exerts an important effect on the particle shape of the SnO ₂ powder is preferably adjusted within a predetermined range. That is, in the case of Sn, it is preferable that the aging treatment is performed at 20 to 60 ° C, the concentration of the aqueous solution containing Sn is 1 to 2N, and the precipitate of Sn is preferably formed at a pH of 4 to 10 and a temperature of 10 to 90 ° C. Do. The conditions for forming a precipitate from the In-containing salt solution are pH 4 to 10, the temperature is 10 to 90 ℃. And it is preferable that the density | concentration of an In containing salt solution is 0.1-2N. SnO ₂ is In ₂ O ₃ on the reason a great influence on the sintered density of the sintered body according to the manufacturing method is In ₂ O _3, with compaction since it has a cubic (cubic) structure, in the case of the sintered final sintered In ₂ O ₃ as compared This is because they go through the process of being replaced by.

In this way, if the precipitation and aging treatment conditions of In and Sn are controlled within the above range, the finely dispersed fine SnO ₂ powder is well substituted with In ₂ O ₃ upon sintering and does not cause pore generation during densification. If precipitation and aging treatment conditions are not properly controlled, strong agglomeration occurs and there is a clear limit to increase dispersibility even by subsequent dispersion treatment.

Hereinafter, the method for preparing ITO powder according to the present invention will be described in detail.

First, a precipitant is injected into an In-containing salt solution and a Sn-containing salt solution, respectively, to form a precipitate. Here, ammonia water, ammonia carbonate water, or the like is used as the precipitant. In this case, as the In-containing salt solution, one obtained by dissolving indium nitrate (In (NO ₃ ) ₃ ) in water is used. The conditions for forming a precipitate from the In-containing salt solution are pH 4 to 10 and a temperature of 10 to 90 ° C. And it is preferable that the density | concentration of an In containing salt solution is 0.1-2N. If the concentration of the In-containing salt solution is less than 0.1N, it is not preferable because the amount of precipitation is too small and if it exceeds 2N, the viscosity is too high after precipitation, making it difficult to prepare uniformly. The Sn-containing salt solution is a solution of tin tetrachloride (SnCl ₄ ) dissolved in water. The conditions for forming a precipitate from the Sn-containing salt solution are pH 4 to 10 and a temperature of 10 to 90 ° C. as in the case of In. And it is preferable that the density | concentration of Sn solution is 1-2N. If the concentration of the salt solution containing Sn is less than 1N, the cohesive force between the particles is so strong that the sintered density is lowered, if it exceeds 2N, the viscosity is too high after precipitation is not preferable because it is difficult to produce uniformly.

Subsequently, the precipitated powders obtained from the above steps are respectively aged. In this case, In is preferably made at 20 to 100 ° C, and Sn is preferably made at 20 to 60 ° C. If the aging treatment temperature of In is out of the above range, additional temperature control device and hydrothermal reaction device should be installed during precipitation, and if the aging treatment temperature of Sn is less than 20 ℃, an additional low temperature control temperature control device is required. When it exceeds C, since it causes aggregation between particles, it is not preferable.

After the aging treatment is completed, the resultant is filtered, and then subjected to a dispersion process with a dispersant. In this case, the dispersant may be an alcohol having 1 to 4 carbon atoms, and specific examples thereof include methanol and ethanol. In the dispersion treatment, the temperature is preferably 10 to 50 ° C., and the processing time is performed for 5 to 50 hours. If the dispersion treatment temperature is less than 10 ℃ difficult to control the temperature, if the dispersion treatment temperature exceeds 50 ℃ alcohol is not preferred because it is volatilized.

Thereafter, the dispersed product is dried. At this time, the drying temperature is 70 to 120 ℃. Subsequently, when the dried product is heat-treated in an air atmosphere, corresponding oxides In ₂ O ₃ powder and SnO ₂ powder may be obtained, respectively. In this case, the primary particle diameter of the In ₂ O ₃ powder is 10 to 80 nm, the primary particle diameter of the SnO ₂ powder is 10 to 80 nm. Thus, the primary particle diameter of ITO powder is 80 nm or less, and it becomes finer compared with the conventional case.

The heat treatment temperature is preferably 500 to 900 ℃. If the heat treatment temperature is less than 500 ℃ remaining residual NO ₃ or Cl and if it exceeds 900 ℃ there is a problem of lowering the sintered density due to the generation of non-uniform and large particles.

When the In ₂ O ₃ powder and the SnO ₂ powder are mixed at a predetermined mixing ratio, the ITO powder of the present invention is obtained. At this time, the mixing ratio of the In ₂ O ₃ powder and SnO ₂ powder is preferably 85:15 to 95: 5 weight ratio. If the content of In ₂ O ₃ powder exceeds the above range the electrical conductivity is lowered, if less than the above range is left unsubstituted SnO ₂ .

In addition, according to the manufacturing method of the present invention, when the mixture of the In ₂ O ₃ powder and SnO ₂ powder is molded and sintered in an air atmosphere, a high density ITO sintered body, that is, an ITO target can be obtained. Here, sintering is performed at 1400 to 1600 ° C. In this sintering step, a process of replacing Sn in the cubic structure of In occurs and densifies.

Hereinafter, the present invention will be described in detail with reference to the following examples, but the present invention is not limited only to the following examples.

Example 1

70 ml of precipitant 5N NH ₄ OH was added to 150 ml of 1N In (NO ₃ ) ₃ solution to adjust the pH to 5 at 25 ° C. to form a precipitate, followed by aging treatment at 80 ° C. at 400 rpm for 1 hour. It was.

Thereafter, the reaction mixture was filtered, washed with distilled water, and 100 ml of ethanol was added to the resultant, which was dispersed at 30 ° C. for 15 hours with stirring at 300 rpm. After the dispersion treatment was completed, dried at 80 ℃ for 24 hours, and then calcined at 600 ℃ to obtain an In ₂ O ₃ powder. In this case, the primary particle diameter of the In ₂ O ₃ powder was 20 to 40 nm.

Separately, 200 ml of precipitant 5N NH ₄ OH was added to 150 ml of 1N SnCl ₄ solution to adjust the pH to 9 at 25 ° C. to form a precipitate, followed by aging treatment at 25 ° C. at 400 rpm for 24 hours.

Thereafter, the reaction mixture was filtered and then washed with distilled water, and 100 ml of ethanol was added thereto, and the mixture was dispersed for 15 hours at 30 ° C. while stirring at 300 rpm. After the dispersion treatment was completed, dried at 80 ℃ for 24 hours, and then calcined at 600 ℃ to obtain a SnO ₂ powder. At this time, the primary particle diameter of the SnO ₂ powder was 20 to 40 nm.

The In ₂ O ₃ powder and SnO ₂ powder prepared according to the above process were mixed at a weight ratio of 9: 1, and molded at a pressure of 3 ton / cm 2 using CIP, and heated to 1500 ° C. at a temperature rising rate of 5 ° C./min. At this temperature, the mixture was sintered in an air atmosphere for 2 hours to obtain an ITO sintered body.

Example 2

Except the matter mentioned later, it carried out according to the same method as Example 1, and obtained the ITO sintered compact.

0.5N In (NO ₃ ) ₃ was used instead of 1N In (NO ₃ ) ₃ as the In source, and the temperature was adjusted to 25 ° C. and the final pH was 9 when forming precipitates from the In and Sn solutions. In the aging treatment, the In solution was maintained for 24 hours with stirring at 400 rpm at 80 ° C., and the Sn process was aged in the same manner as in the In solution except for 25 ° C. . However, the calcining temperature of In ₂ O ₃ was 700 ° C. At this time, the primary particle diameter of the In ₂ O ₃ powder was 30 to 50 nm, the primary particle diameter of the SnO ₂ powder was 20 to 40 nm.

Example 3

Except the matter mentioned later, it carried out according to the same method as Example 1, and obtained the ITO sintered compact.

Upon precipitate formation from In and Sn solutions, the temperature was adjusted to 25 at < RTI ID = 0.0 > 25 C. < / RTI > In the case of both In and Sn solutions, the aging treatment was performed by stirring at 25 ° C. at 400 rpm for 24 hours. After the aging treatment of the In solution and the Sn solution was carried out as described above, each reaction mixture was filtered, washed with distilled water, and 100 ml of ethanol was added, and the resultant was mixed at 300 rpm for 15 hours at 30 ° C. During the dispersion. After the dispersion treatment was completed, dried at 80 ℃ for 24 hours, and then calcined at 600 ℃ to obtain In ₂ O ₃ powder and SnO ₂ powder, respectively. At this time, the primary particle diameter of the In ₂ O ₃ powder was 20 to 40 nm, the primary particle diameter of the SnO ₂ powder was 20 to 40 nm.

Comparative Example 1

70 ml of 5N NH ₄ OH was injected into 150 ml of 1N In (NO ₃ ) ₃ solution to adjust the pH to 9 at 25 ° C. to form a precipitate.

Thereafter, the reaction mixture was filtered and then washed with distilled water and ethanol was used as a washing solution in the final filtration. After the filtration process, the resultant was dried for 24 hours at 80 ℃ and calcined at 600 ℃ to obtain an In ₂ O ₃ powder. In this case, the primary particle diameter of the In ₂ O ₃ powder was 20 to 40 nm.

Separately, it was dissolved in 150 ml of 1N SnCl ₄ solution, and then, 140 ml of precipitant 5N NH ₄ OH was added thereto to adjust the pH to 5 at 25 ° C. to form a precipitate.

Thereafter, the reaction mixture was filtered and then washed with distilled water and ethanol was used as a washing solution in the final filtration. After the filtration process, the resultant was dried for 24 hours at 80 ℃ and calcined at 600 ℃ to obtain a SnO ₂ powder. At this time, the primary particle diameter of the SnO ₂ powder was 20 to 40 nm.

The In ₂ O ₃ powder and SnO ₂ powder prepared according to the above process were mixed at a weight ratio of 9: 1, and molded at a pressure of 3 ton / cm 2 using CIP, and heated to 1500 ° C. at a temperature rising rate of 5 ° C./min. At this temperature, the mixture was sintered in an air atmosphere for 2 hours to obtain an ITO sintered body.

Comparative Example 2

70 ml of precipitant 5N NH ₄ OH was added to 150 ml of 1N In (NO ₃ ) ₃ solution, and the pH was adjusted to 5 at 25 ° C. to form a precipitate, and the resultant was stirred for 24 hours at 400 rpm at 25 ° C. aging) treatment.

Thereafter, the reaction mixture was filtered and then washed with distilled water and ethanol was used as a washing solution in the final filtration. After filtration, the resultant was dried at 80 ° C. for 24 hours and calcined at 600 ° C. to obtain an In ₂ O ₃ powder. In this case, the primary particle diameter of the In ₂ O ₃ powder was 20 to 40 nm.

Separately, 200 ml of precipitant 5N NH ₄ OH was added to 150 ml of 1N SnCl ₄ solution to adjust the pH to 9 at 25 ° C. to form a precipitate, and the resultant was stirred for 24 hours at 400 ° C. at 25 ° C. for aging treatment. Was carried out.

Thereafter, the reaction mixture was filtered and then washed with distilled water and washed with ethanol as a washing solution in the final filtration. After filtration, the resultant was dried at 80 ° C. for 24 hours and then calcined at 600 ° C. to obtain a SnO ₂ powder. At this time, the primary particle diameter of the SnO ₂ powder was 20 to 40 nm.

The In ₂ O ₃ powder and SnO ₂ powder prepared according to the above process were mixed at a weight ratio of 9: 1, and molded at a pressure of 3 ton / cm 2 using CIP, and heated to 1500 ° C. at a temperature rising rate of 5 ° C./min. At this temperature, the mixture was sintered in an air atmosphere for 2 hours to obtain an ITO sintered body.

Comparative Example 3

145 ml of precipitant 5N NH ₄ OH was added to 150 ml of 1N In (NO ₃ ) ₃ solution to adjust the pH to 9 at 25 ° C. to form a precipitate, and the resultant was aged by stirring at 400 ° C. at 25 ° C. for 24 hours. aging) treatment.

Thereafter, the reaction mixture was filtered, washed with distilled water, and 100 ml of ethanol was added, and the resultant was dispersed for 15 hours at 30 DEG C while mixing at 300 rpm. After the dispersion treatment was completed, the resultant was dried at 80 ° C. for 24 hours and calcined at 600 ° C. to obtain an In ₂ O ₃ powder. In this case, the primary particle diameter of the In ₂ O ₃ powder was 20 to 40 nm.

Separately, 200 ml of precipitant 5N NH ₄ OH was added to 150 ml of 1N SnCl ₄ solution to adjust the pH to 9 at 25 ° C. to form a precipitate, and the resultant was stirred for 24 hours at 80 ° C. at 400 rpm for 24 hours. Was carried out.

Thereafter, the reaction mixture was filtered, washed with distilled water, and 100 ml of ethanol was added, and the resultant was dispersed for 15 hours at 30 DEG C while mixing at 300 rpm. After the dispersion treatment was completed, the resultant was dried at 80 ° C. for 24 hours and calcined at 800 ° C. to obtain a SnO ₂ powder. At this time, the primary particle diameter of the SnO ₂ powder was 60 to 80 nm.

The In ₂ O ₃ powder and SnO ₂ powder prepared according to the above process are mixed at a weight ratio of 9: 1, and molded using a CIP at a pressure of 3 ton / cm 2 and heated to 1500 ° C. at a temperature rising rate of 5 ° C./min. At this temperature, the mixture was sintered in an air atmosphere for 2 hours to obtain an ITO sintered body.

Comparative Example 4

145 ml of precipitant 5N NH ₄ OH was injected into 150 ml of 1N In (NO ₃ ) ₃ solution, and the precipitate was formed at 25 ° C. by adjusting the pH to 9, and the resultant was stirred at 400 rpm for 1 hour at 24 ° C. at 24 ° C. The aging treatment was performed while keeping the time.

Thereafter, the reaction mixture was filtered, washed with distilled water and ethanol was added, and the mixture was dispersed for 15 hours at 30 ° C. while mixing at 300 rpm. After the dispersion treatment was completed, the resultant was dried at 80 ° C. for 24 hours and calcined at 600 ° C. to obtain an In ₂ O ₃ powder. In this case, the primary particle diameter of the In ₂ O ₃ powder was 20 to 40 nm.

Separately, 150 ml of 0.5 N SnCl ₄ solution was injected with 100 ml of precipitant 5N NH ₄ OH to adjust pH to 9 at 25 ° C. to form a precipitate. Aging was performed by stirring at 400 rpm at 80 ° C. for 24 hours.

Thereafter, the reaction mixture was filtered, washed with distilled water and ethanol was added, and the resultant was dispersed for 15 hours at 30 DEG C while mixing at 300 rpm. After the dispersion treatment was completed, the resultant was dried at 80 ° C. for 24 hours and calcined at 600 ° C. to obtain a SnO ₂ powder. At this time, the primary particle diameter of the SnO ₂ powder was 30 to 50 nm.

The In ₂ O ₃ powder and SnO ₂ powder prepared according to the above process were mixed at a weight ratio of 9: 1, and molded at a pressure of 3 ton / cm 2 using CIP, and heated to 1500 ° C. at a temperature rising rate of 5 ° C./min. At this temperature, the mixture was sintered in an air atmosphere for 2 hours to obtain an ITO sintered body.

According to Examples 1 to 3, the aging treatment was performed by maintaining for 1 hour or 24 hours while stirring at 400 rpm at 25 ° C or 80 ° C. After filtration, dispersibility between powders was increased by dispersing for 15 hours at 30 ° C. using ethanol.

On the contrary, in Comparative Example 1, neither the aging treatment nor the alcohol dispersion treatment was performed. In the case of Comparative Example 2, the alcohol dispersion treatment was performed while the aging treatment was carried out by maintaining the reaction mixture for 24 hours with stirring at 400 rpm. Did not do it. In Comparative Examples 3 and 4, both the aging treatment and the alcohol dispersion treatment were performed. In Comparative Example 3, the temperature of Sn was high at 80 ° C., and the initial concentration of the Sn-containing salt solution was 0.5N. Low.

The densities of the ITO sintered bodies prepared according to Examples 1 to 3 and Comparative Examples 1 to 4 were measured.

As a result of the measurement, the density of the ITO sintered compact of Example 1 was 98.36% compared with the theoretical density, the density of the ITO sintered compact of Example 2 was 98.12% compared with the theoretical density, and the density of the ITO sintered compact of Example 3 was 97.4% compared with the theoretical density , The density of the ITO sintered compact of Comparative Example 1 is 84% of the theoretical density, the density of the ITO sintered compact of Comparative Example 2 is 92% of the theoretical density, the density of the ITO sintered compact of Comparative Example 3 is 93% of the theoretical density, The density | concentration of the ITO sintered compact of Example 4 is 86% with respect to theoretical density.

From the above results, in particular, when comparing the results of Examples and Comparative Examples 1 and 2, it was found that the aging treatment and the alcohol dispersion treatment were effective in increasing the density of the ITO sintered compact. However, in Comparative Examples 3 and 4 In the case of, for aging treatment and even if carried out all the alcohol dispersion treatment according to the manufacturing conditions of the SnO ₂ is particularly the case for manufacturing the aging temperature of the SnO ₂ as high as 80 ℃ when the initial concentration lowered to 0.5 It was confirmed that the sintered density of the ITO sintered compact was sharply lowered. It was found that, in the case of SnO ₂ , the dispersibility of the particles could not be increased even by dispersing when initially aggregated. Therefore, in the case of SnO ₂ , the concentration of Sn should be controlled to 1 to 2N during precipitation as in the case of Example 1-3, and the aging treatment should also be controlled to be in the range of 20 to 60 ° C. Highly dispersed ITO powder in the calcination process could be prepared.

According to the present invention, the primary particle size of the ITO powder is refined to 80 nm or less, and precipitation conditions and aging treatments such as concentration, pH, and temperature of the In-containing salt solution and the Sn-containing salt solution are prepared in the preparation of In ₂ O ₃ and SnO ₂ . By controlling the conditions within an appropriate range, the degree of Sn substitution in the cubic structure of In ₂ O ₃ during sintering is increased to prevent the formation of pores during densification, and the alcohol dispersion before drying after filtration during preparation of In ₂ O ₃ powder and SnO ₂ powder By the treatment, a densified ITO sintered body can be obtained.

Claims (9)

(a) injecting a precipitant into the In-containing salt solution and the Sn-containing salt solution, respectively, to form a precipitate; (b) aging the precipitates obtained from step (a), respectively; (c) filtering the resultant obtained from step (b), and then dispersing the mixture at 10 to 50 ° C. with an alcohol having 1 to 4 carbon atoms as a dispersant; And (d) drying the resultant obtained from step (c), and then heat-treating them to obtain In ₂ O ₃ powder and SnO ₂ powder, respectively, and mixing them. In the step (b), in the case of In the aging treatment is made at 20 to 100 ℃, in the case of Sn is the method of producing indium tin oxide (ITO), characterized in that made in 20 to 60 ℃. The method of claim 1, further comprising the step of sintering the mixture of In ₂ O ₃ powder and SnO ₂ powder obtained from the step (d) in a molding and air atmosphere to obtain an ITO sintered body. The method of claim 1, wherein the mixed weight ratio of In ₂ O ₃ powder and SnO ₂ powder in step (d) is 85:15 to 95: 5. The method according to claim 2, wherein in the step of obtaining the ITO sintered compact, the sintering temperature is 1400 to 1600 ° C. The method of claim 2, wherein in step (b), in the case of In, the aging treatment is performed at 20 to 100 ° C, and in the case of Sn, the aging treatment is performed at 20 to 60 ° C. The method of claim 2, wherein the dispersing agent of step (c) is an alcohol having 1 to 4 carbon atoms and the dispersing treatment is carried out at 10 to 50 ℃. The method of claim 1 or 2, wherein the heat treatment temperature of the step (d) is performed at 500 to 900 ℃. According to claim 1 or 2, wherein the concentration of the In-containing salt solution of the step (a) is 0.1 to 2N, the concentration of the Sn-containing salt solution is 1 to 2N, The precipitate of In and Sn is formed at pH 4-10, temperature 10-90 degreeC. The method of claim 1, wherein the primary particle diameter of the In ₂ O ₃ powder and SnO ₂ powder obtained in the step (d) is 80nm or less.