KR100891952B1 - Oxide-based target for transparent conductive film and method for manufacturing the same, and oxide-based transparent conductive film - Google Patents

Abstract

An oxide-based target for a transparent conductive film is provided to manufacture a uniformly conductive film by using single phase or homogeneous phase oxide in a synthesizing process in order to prevent phase separation for a sintering process. An oxide-based target for a transparent conductive film comprises the following steps of: preparing a metal salt solution with a pH of 1~4 by adding a pH adjusting agent to a solution containing two different sorts of metal salts; adding alkali materials to the metal salt solution and adjusting the pH to a range of 7~10 while maintaining a temperature of 10~80°C to obtain metal hydroxide precipitate; drying the metal hydroxide precipitate to obtain metal hydroxide powder; heat-treating the metal hydroxide powder at 500~800°C to obtain metal oxide powder; and pulverizing the metal oxide powder.

Description

OXIDE-BASED TARGET FOR TRANSPARENT CONDUCTIVE FILM AND METHOD FOR MANUFACTURING THE SAME, AND OXIDE-BASED TRANSPARENT CONDUCTIVE FILM}

The present invention relates to an oxide-based target for a transparent conductive film, a method for manufacturing the same, and an oxide-based transparent conductive film. More particularly, in forming a target as an oxide sintered body, oxygen concentration is depleted to increase free electron concentration. The present invention relates to an oxide-based target for a transparent conductive film having excellent electrical conductivity, a method for producing the same, and an oxide-based transparent conductive film.

The transparent conductive film is not only used as an electrode of a solar cell, a liquid crystal display (LCD), and various light-sensitive elements, but also a heat reflecting film and an anti-static film for automobile windows or construction. In addition, it is widely used as an anti-fogging transparent body such as freezer show cases. The transparent conductive film (transparent electrode) is required to have high light transmittance and electrical conductivity. For example, the transparent conductive film (transparent electrode) should have a light transmittance of 85% or more in the visible light region, and a resistivity of less than 1 × 10 ⁻³ Pa · cm. The transparent conductive film having a low resistance is particularly suitable for surface elements or touch panels, such as solar cells, liquid crystals, organic electroluminescence (EL), and inorganic electroluminescence (EL).

As the transparent conductive film (transparent electrode), a tin oxide based (SnO ₂ ) based thin film, a zinc oxide based (ZnO) based thin film, an indium oxide (In ₂ O ₃ ) based thin film, and the like are known. The tin oxide-based transparent thin film mainly includes antimony as a dopant (ATO thin film) or fluorine as a dopant (FTO thin film). The zinc oxide transparent thin film mainly includes aluminum as a dopant (AZO thin film) or gallium as a dopant (GZO thin film). Indium oxide oxide thin films include indium tin oxide (ITO) thin films, and indium zinc oxide (IZO) thin films, and the ITO and IZO thin films. Silver is widely used as an electrode material because of its good optical and electrical properties.

The transparent conductive film (projection electrode) is mainly produced by the sputtering method or the ion plasma method. In particular, the sputtering method is effective when it is necessary to precisely control the film formation and the film thickness of a material having low vapor pressure, and its operation is very simple and convenient and widely used. In manufacturing a thin film by the sputtering method, a target, which is a raw material of the thin film, is used. The target is a solid containing a metal element constituting a thin film by film formation, and a sintered body such as metal, metal oxide, metal nitride, metal carbide, or the like is used, or a single crystal is used in some cases.

The sputtering method generally uses an apparatus having a vacuum chamber in which a substrate and a target can be disposed therein. The film formation of a thin film (transparent conductive film) by the sputtering method is as follows.

First, the base and the target are placed in a vacuum chamber, and then made into a high vacuum, and then a rare gas such as Irgon is injected to control the inside of the vacuum chamber to a gas pressure of about 10 Pa or less. The substrate is used as the anode, and the target is used as the cathode, so that an argon plasma is generated by glow discharge between the two. At this time, the argon cations in the plasma collide with the target, which is the cathode, and the target constituent particles bounced off by the collision are deposited on the substrate to form a thin film (transparent conductive film).

The sputtering method is classified into a high frequency sputtering method using a high frequency plasma and a DC sputtering method using a DC plasma. The DC sputtering method has a faster film forming speed, a lower power unit, and a simpler and easier film forming process than the high frequency sputtering method. That is, when the same electric power is charged with respect to the same target in the film-forming speed, the DC sputtering method is about 2-3 times faster. Therefore, in consideration of productivity and manufacturing cost, the DC sputtering method is advantageous over the high frequency sputtering method. In addition, since the DC sputtering method increases the deposition rate when charging high DC power, it is preferable to charge high DC power in order to increase productivity. At this time, the target should be stable for high DC power. That is, the target should be capable of stable film formation without abnormal sputtering even when charged with high DC power.

The deposition rate during sputtering is closely related to the chemical bonding of the target material. The sputtering method utilizes a phenomenon in which argon cations having kinetic energy collide with the target surface and materials on the target surface are energized and released. Thus, the weaker the ionic or atomic bonds of the materials constituting the target, the more likely it is to be released by sputtering.

Further, as a method for forming an oxide transparent conductive film such as an ITO thin film by sputtering, a reaction sputtering method for forming a film in a mixed gas of argon and oxygen using an alloy target (In-Sn alloy in the case of ITO film) of a film constituent metal, There are two methods of reaction sputtering, in which an oxide sintered body (In-Sn-O sintered body in the case of ITO film) made of an oxide of a film constituent metal is formed in a mixed gas of argon and oxygen.

In the method using the alloy target, all of the oxygen in the prepared transparent conductive film must be supplied from oxygen in the atmosphere. However, this method is difficult to keep the fluctuations in the amount of oxygen gas in the atmosphere small, making it difficult to produce a transparent conductive film having a uniform thickness and uniform characteristics. This is because the film formation rate or the characteristics (specific resistance and transmittance) of the manufactured thin film are extremely dependent on the oxygen gas introduced in the atmosphere.

On the other hand, the method using the oxide target reduces the variation of the amount of oxygen gas in the atmosphere gas compared to the case of using the alloy target because only a part of oxygen supplied to the thin film is supplied from the target itself, and only oxygen deficiency is provided as the oxygen gas. You can. As a result, compared with the case of using an alloy target, manufacture of the transparent conductive film which has uniform thickness and a uniform characteristic is easy. Accordingly, in recent years, a method of using an oxide sintered body as a target has been widely adopted.

On the other hand, ITO is mainly used as an indium oxide as a target for a transparent conductive film, but ITO has a problem in that the manufacturing method is complicated and the manufacturing cost is high. Accordingly, non-indium targets are required. As described above, non-indium-based zinc oxides such as GZO and AZO, and tin oxides such as FTO and ATO are known, but have not yet reached the characteristics of ITO in electrical conductivity and transparency. When the film is formed by the DC sputtering method, a high voltage is required in the sputtering process, and therefore, the target must have high electrical conductivity.A conventional zinc oxide (GZO, AZO, etc.) or tin oxide (FTO, ATO, etc.) target has an electrical conductivity. Low problems include abnormal discharge, target cracking, and nodule.

In addition, in manufacturing the conventional oxide target, it is manufactured by the following method. First, two or more kinds of different oxide powders such as indium oxide powder and zinc oxide powder are quantitatively mixed, and then wet pulverized using water as a medium. Thereafter, the pulverized powder is dried and filtered, and then a binder is added to prepare a molded article having a desired target shape. The molded article is produced by high temperature sintering in an air atmosphere.

However, the manufacturing method according to the prior art as described above has a problem in that it is not homogeneous due to phase separation (oxides are separated from each other) during the sintering. Accordingly, cracks or nodules are generated during sputtering, and it is difficult to form a uniform conductive film. In addition, there is a problem that the electrical conductivity is lowered because the density of the target is not dense.

The present invention is to solve the problems of the prior art as described above, in constructing a target including an oxide sintered body, the oxide for the transparent conductive film having an excellent electrical conductivity by increasing the concentration of free electrons by deficiency of oxygen in the oxide sintered body It is an object to provide a system target and a transparent conductive film.

In addition, the present invention, in the production of an oxide-based target for a transparent conductive film, by synthesizing a single phase or a homogeneous oxide from two or more different metal salts using a coprecipitation method, phase separation in the sintering process is prevented and uniform conductivity An object of the present invention is to provide a method for producing an oxide-based target for a transparent conductive film which can form a film, has an oxygen deficient structure and has a dense density, and has excellent electrical conductivity.

In order to achieve the above object, the present invention provides an oxide-based target for a transparent conductive film comprising an oxide sintered body represented by the following general formula, which is partially deficient in oxygen.

[General Formula]

M _m O _{n -α} (M ' _x O _{y -β} ) _γ (M " _p O _{q -δ} ) _ε

(Wherein M and M 'and M "are different metals; m, n, x, y, p and q are integers greater than or equal to 1 and γ and ε are zero or greater than zero; α, β And δ is a number greater than 0; n> α, y> β, q> δ.)

At this time, M of the general formula is indium (In), zinc (Zn), aluminum (Al), gallium (Ga) germanium (Ge), magnesium (Mg), tin (Sn), zirconium (Zr), hafnium (Hf) ), Cerium (Ce), thallium (Tl), antimony (Sb), calcium (Ca), titanium (Ti), tungsten (W) and the like. More preferably, M of the general formula is indium (In) or zinc (Zn), M 'and M "are indium (In), zinc (Zn), aluminum (Al), gallium (Ga) germanium (Ge) ), Magnesium (Mg), tin (Sn), zirconium (Zr), hafnium (Hf), cerium (Ce), thallium (Tl), antimony (Sb), calcium (Ca), titanium (Ti) and tungsten (W ), And the weight ratio [M / (M + M '+ M ") of the general formula M is preferably 0.1 to 0.99.

In addition, the present invention,

A first step of obtaining a metal salt solution having a pH of 1 to 4 by adding a pH adjusting agent to a solution containing two or more different metal salts;

A second step of adding alkali to the metal salt solution of the first step so as to have a pH of 7 to 10 and then maintaining a 10 to 80 ° C. to obtain a metal hydroxide precipitate;

A third step of drying the precipitate of the second step to obtain a metal hydroxide powder;

A fourth step of obtaining the metal oxide powder by heat-treating the metal hydroxide powder of the third step at 500 to 800 ° C .;

A fifth step of grinding the metal oxide powder of the fourth step;

A sixth step of manufacturing a molded body using the powder of the fifth step;

A seventh step of sintering the molded body of the sixth step; And

It provides a method for producing an oxide-based target for a transparent conductive film comprising an eighth step of cooling the sintered body of the seventh step.

At this time, the sintering of the seventh step, it is preferable to include the step of maintaining the oxygen concentration in the sintering furnace lower than the oxygen concentration in the atmosphere and sintering. More preferably, the sintering of the seventh step, the first step (burn-out process) for raising the temperature inside the sintering furnace to 900 ℃ in the oxygen atmosphere, and maintaining the oxygen concentration in the sintering furnace lower than the oxygen concentration in the atmosphere And a second step (sintering step) of sintering by raising the temperature to 1000 ° C. or more, wherein the second step is maintained in a reducing or inert atmosphere of 200 to 500 l per 1.0 m 3 of the internal volume of the sintering furnace, and is 1250 to 1550 ° C. It is recommended to proceed for 10 to 20 hours at the temperature. In addition, the cooling of the eighth step is preferably carried out by keeping the oxygen concentration in the sintering furnace equal to the oxygen concentration in the atmosphere or lower than the oxygen concentration in the atmosphere.

Moreover, this invention provides the oxide type transparent conductive film containing the oxide represented by the said general formula.

According to the present invention, in contrast to the conventional targets composed of oxides such as In ₂ O ₃ (ZnO) _γ or ZnO (In ₂ O ₃ ) _γ , oxygen conductivity is intentionally deficient and excellent electrical conductivity is achieved by increasing free electron concentration. Has In addition, according to the present invention, phase separation in the sintering process is prevented and has a dense density. Accordingly, cracks or nodules are prevented during sputtering and a uniform conductive film is formed.

In addition, in the DC sputtering method, high voltage is required, and at this time, the target should have high electrical conductivity. The oxide-based target for transparent conductive film according to the present invention has excellent electrical conductivity due to oxygen deficiency and thus abnormal discharge during high voltage DC sputtering. It has the effect of preventing cracks and nodule from occurring.

Hereinafter, the present invention will be described in detail.

The oxide target for transparent conductive films according to the present invention (hereinafter abbreviated as 'target') includes an oxide sintered body represented by the following general formula.

[General Formula]

M _m O _{n -α} (M ' _x O _{y -β} ) _γ (M " _p O _{q -δ} ) _ε

(Wherein M and M 'and M "are different metals; m, n, x, y, p and q are integers greater than or equal to 1 and γ and ε are zero or greater than zero; α, β And δ is a number greater than 0; n> α, y> β, q> δ.)

The oxide sintered body represented by the above general formula has a crystal structure deficient in oxygen, and according to the present invention, the oxide sintered body having the oxygen deficient structure as described above has excellent electrical conductivity by increasing free electron concentration. At this time, in the oxide sintered body of the general formula, M is the parent, M 'and M "doped structure, the weight ratio of M (M / (M + M' + M") based on the metal is 0.1 ~ 0.99 is good.

In addition, M which is a matrix of the oxide sintered body is indium (In), zinc (Zn), aluminum (Al), gallium (Ga) germanium (Ge), magnesium (Mg), tin (Sn), zirconium (Zr), It is preferably any one selected from the group consisting of metals such as hafnium (Hf), cerium (Ce), thallium (Tl), antimony (Sb), calcium (Ca), titanium (Ti) and tungsten (W). More preferably, M, which is a matrix of the oxide sintered body, is preferably selected from indium (In) or zinc (Zn) having excellent electrical conductivity. At this time, the general formula is represented by In ₂ O _{3 -α} (M _x 'O _{y -β} ) _γ (M " _p O _{q -δ} ) _ε when indium (In) is the mother (M = In), zinc ( When Zn) is the parent (M = Zn), ZnO _{1 -α} (M _x 'O _{y -β} ) _γ (M " _p O _{q -δ} ) _ε is represented. In the case of using indium (In) as a matrix, since the manufacturing cost can be increased due to the rareness of the indium (In) metal, the oxide sintered body is zinc-based which uses a small amount of indium (In) or does not use indium (In) at all. Even more preferred is an oxide sintered body.

M 'and M "of the general formula are indium (In), zinc (Zn), aluminum (Al), gallium (Ga) germanium (Ge), magnesium (Mg), tin (Sn), zirconium (Zr), hafnium (Hf), cerium (Ce), thallium (Tl), antimony (Sb), calcium (Ca), titanium (Ti) and tungsten (W) may be selected from the group consisting of metals. Is selected from the above-listed metals, for example, when indium (In) is the parent (M = In), the general formula is In ₂ O _{3 -α} (ZnO _{1 -β} ) _γ , In ₂ O _{3 -α} (Al ₂ O _{3 -β} ) _γ , In ₂ O _{3 -α} (Ga ₂ O _{3 -β} ) _γ , In ₂ O _{3 -α} (GeO _{2 -β} ) _γ , In ₂ O _{3 -α} (MgO _{1 -β} ) _γ , In ₂ O _3-α (SnO _{2 -β} ) _γ , In ₂ O _{3 -α} (ZrO _{2 -β} ) _γ , In ₂ O _{3 -α} (HfO _{2 -β} ) _γ , In ₂ O _{3 -α} (CeO _{2 -β} ) _γ , In ₂ O _{3 -α} (Tl ₂ O _{3 -β} ) _γ , In ₂ O _{3 -α} (Sb ₂ O _{3 -β} ) _γ , In ₂ O _{3 -α} (CaO _{1 -β} ) _γ , In ₂ O _{3 -α} (TiO _{2 -β} ) _γ , In ₂ O _{3 -α} (WO _{3 -β} ) _γ , In ₂ O _{3 -α} (ZnO _{1 -β} ) _γ ( SnO _{2 -δ} ) _ε , In ₂ O _{3 -α} (ZnO _{1 -β} ) _γ (Ga ₂ O _{3 -δ} ) _ε , In ₂ O _{3 -α} (ZnO _{1 -β} ) _γ (HfO _{2 -δ} ) _ε or In ₂ O _{3 -α} (SnO _{2 -β} ) _γ (CeO _{2 -δ} ) _ε When ZnO is the parent (M = Zn), the general formulas are ZnO _{1 -α} (In ₂ O _{3 -β} ) _γ , ZnO _{1 -α} (Al ₂ O _{3 -β} ) _γ , ZnO _{1 -α} (Ga ₂ O _{3 -β} ) _γ , ZnO _{1 -α} (Sb ₂ O _{3 -β} ) _γ , ZnO _{1 -α} (MgO _{1 -β} ) _γ , ZnO _{1 -α} (SnO _{2 -β} ) _γ , ZnO _{1 -α} (GeO _{2 -β} ) _γ , ZnO _{1 -α} (Al ₂ O _{3 -β} ) _γ (Ga ₂ O _{3 -δ} ) _ε or ZnO _{1 -α} (Al ₂ O _{3 -β} ) _γ ( It may be a binary oxide sintered body (γ is not 0 and ε is 0) or a tertiary oxide sintered body (when γ and ε are not 0) represented by various forms such as MgO _{1 -δ} ) _ε . In addition, the general formula may be a one-way oxide sintered body (when γ and ε are 0) represented by In ₂ O _{3 -α} or ZnO _{1 -α} .

The target according to the present invention, including the oxide sintered body intentionally deficient in oxygen, has excellent electrical conductivity and thin film properties. For example, in the case of In ₂ O _{3 -α} (ZnO _{1 -β} ) _γ having indium (In) as a parent (M = In), an oxide (ITO) target of the conventional In ₂ O ₃ (ZnO) _γ type Oxygen deficiency increases free electron concentration, resulting in excellent electrical conductivity. In addition, compared with conventional non-indium oxide targets such as ZTO, AZO, GZO and the like, it has excellent thin film characteristics as well as electrical conductivity.

The target according to the invention can be produced by the process of the invention described below. According to the production method of the present invention, it is possible to prevent the phase separation in the sintering process that is a problem in the prior art and to produce a target having a dense density. As a result, cracks or nodules can be prevented during sputtering and a uniform conductive film can be formed. Further, as represented by the above general formula, a target (oxide sintered body) having excellent electrical conductivity can be produced.

Hereinafter, the manufacturing method of the target which concerns on this invention is demonstrated. 1 shows a manufacturing process diagram of the present invention.

First, a solution containing two or more different metal salts is prepared. In this case, the metal salt may be selected from inorganic salts and organic salts as metal precursors. For example, the metal salt solution may include two or more different metal salts, and a metal salt as a parent selected from indium (In) or zinc (Zn), indium (In), zinc (Zn), aluminum (Al), and gallium. (Ga) Germanium (Ge), magnesium (Mg), tin (Sn), zirconium (Zr), hafnium (Hf), cerium (Ce), thallium (Tl), antimony (Sb), calcium (Ca), titanium ( Metal salts as one or more dopants selected from Ti), tungsten (W) and the like. In this case, the metal salt serving as the mother may be, for example, inorganic salts such as indium nitride, indium chloride, and indium sulfide, and zinc nitride, zinc chloride, zinc sulfide, and the like as zinc, and indium alkoxide and zinc alkoxide. Organic salts, such as these, can be used. In addition, the metal salt added to the dopant is, for example, indium nitride, indium chloride, indium sulfide, aluminum nitride, aluminum chloride, aluminum sulfide, gallium nitride, gallium chloride, gallium sulfide, zinc nitride, zinc chloride, zinc sulfide, or nitrided nitride. Inorganic salts such as tin, tin chloride and tin sulfide; One or two or more selected from organic salts such as indium alkoxide, aluminum alkoxide, gallium alkoxide, zinc alkoxide and tin alkoxide may be used in combination.

As described above, after preparing a solution containing two or more different metal salts, a pH adjusting agent is added to the solution so as to have a pH of 1 to 4, and stirred at 30 to 80 ° C. for 5 to 20 hours to obtain a metal salt solution. The pH adjusting agent may be ultrapure water or weak alkali, and in some cases a weak acid may be used. At this time, when the pH of the metal salt solution exceeds 4, the reaction rate is lowered so that the acidity of the metal salt solution is maintained at pH 4 or less. Next, alkali (NaOH aqueous solution, etc.) is added to the metal salt solution so as to have a pH of 7 to 10. After maintaining the pH in the range of 7 to 10, the temperature is maintained at 10 to 80 ℃ to obtain a metal hydroxide precipitate. By this coprecipitation reaction, a composite obtained by synthesizing two or more different metals is obtained. That is, the precipitates are precipitated (coprecipitated) under conditions in which two or more different metal salts coexist, and the precipitate has a structure in which two or more metals are synthesized. In addition, the synthesized precipitate particles have a uniform particle size distribution of 50 nm or less. At this time, in the coprecipitation reaction condition, when the pH is less than 7, it is difficult to crystallize and the yield of the metal hydroxide precipitate is lowered. When the pH exceeds 10, it is not preferable because a long time is required during the washing / filtration process. In addition, if the reaction holding temperature is less than 10 ℃ has a disadvantage in that the reaction time is long, when it exceeds 80 ℃ it is difficult to produce a fine synthetic powder of 50nm or less resulting in particle growth. This precipitation reaction is preferably performed for 10 to 40 hours in the above temperature range.

After obtaining a precipitate as described above (metal hydroxide precipitates of two or more metals), the precipitate is separated by filtration using a filter press or a centrifuge. The separated precipitate is washed with ultrapure water or alcohol, and then dried by hot air drying or the like. At this time, 80-200 degreeC is suitable for the temperature at the time of drying. The powder (metal hydroxide powder) which has undergone such a drying process is subjected to heat treatment (calcination) and then pulverized. If the drying temperature is too high, exceeding 200 ° C., the cohesive strength of the dry powder becomes so high that the pulverizing ability decreases and the crushing medium (ball It is not preferable because it may cause contamination by wheat).

After the drying process as described above is subjected to a heat treatment (calcination) at a temperature of 500 ~ 800 ℃. Metal hydroxide powder is formed into a metal oxide powder by the heat treatment. In addition, the remaining water and the chemically bound salts are decomposed and removed by the heat treatment. At this time, if the heat treatment (calcination) temperature is less than 500 ° C, volatilization of the remaining salt does not occur completely, and if it exceeds 800 ° C, the particles are sintered (particle growth), which is not preferable. At this time, when the particles are sintered (particle growth) due to the high temperature heat treatment (calcination), subsequent crushing ability is lowered, so that the sintered compact having a dense structure is difficult to increase by increasing the sintering driving force desired in the present invention. The metal oxide powder obtained through such a heat treatment preferably has a distribution having an average particle diameter of 1.0 to 10.0 µm. In addition, the heat-treated powder may have a specific surface area of 10 to 30 m 2 / g.

Next, the heat-treated powder is pulverized. Grinding may be performed by a method such as wet ball grinding, and through this grinding, a target having a higher density can be produced. At this time, according to the present invention, the powder is synthesized in the same manner as described above, it is possible to obtain a powder having an average particle size distribution of 0.5 ~ 1.0㎛ when wet grinding 20 hours or less, 90% or more of the obtained powder is 1.0㎛ or less It can have a particle size distribution.

As described above, after the grinding process is carried out to produce a target molded body of a predetermined shape. At this time, by adding a molding aid (binder) to the pulverized powder is coated on the surface of the particles, it is possible to proceed to the process of drying (powder processing step). When such a powder processing process is advanced, molding density and sintering density can be increased.

After the molded product is manufactured as described above, the molded product is sintered. At this time, the sintering is carried out by maintaining the oxygen concentration in the sintering furnace lower than the oxygen concentration in the atmosphere. The sintering is preferably performed in two processes. Specifically, first, a burn-out process (first process) of removing the binder used as the molding aid is performed. At this time, the first step (burn-out process) proceeds to the method of raising the temperature inside the sintering furnace (electric furnace chamber, etc.) up to 900 ℃ in the oxygen atmosphere (atmosphere atmosphere or injecting high purity air into the sintering furnace). . Next, a substantial sintering step (second step) is performed. At this time, the second step (sintering step) is to maintain the oxygen concentration in the sintering furnace lower than the oxygen concentration in the atmosphere, and proceeds to the method of raising the temperature (sintering) to 1000 ℃ or more, which can cause shrinkage behavior. In the second step (sintering step), the method of maintaining a low oxygen concentration in the sintering furnace may be selected from the method of maintaining the inside of the sintering furnace in a vacuum, or inert gas such as nitrogen. More preferably, the second step (sintering step) is maintained in a reducing or inert atmosphere (nitrogen atmosphere) of 200 to 500 L per 1.0 m 3 of the internal volume of the sintering furnace, for 10 to 20 hours at a temperature of 1250 ~ 1550 ℃ It is good to keep going. At this time, it is good to increase the temperature in the sintering furnace at a rate of 1.0 ~ 1.5 ℃ / min to be in the above temperature range.

After sintering in the same manner as described above, the obtained sintered body is cooled. At this time, the cooling is performed in a state where the sintered body is charged in the sintering furnace, but the oxygen concentration in the sintering furnace is preferably made equal to the oxygen concentration in the atmosphere, or lower than the oxygen concentration in the atmosphere. At this time, when maintaining lower than the oxygen concentration in the atmosphere, 0 to 21% of the oxygen concentration in the atmosphere is good. That is, it is preferable to proceed in an oxygen free atmosphere or 21% or less of oxygen concentration in air. According to the present invention, when sintering (the second step) and cooling are performed in the reducing atmosphere (atmosphere lower than the oxygen concentration in the air) as described above, a high density sintered body is produced, and oxygen is deficient and the electrical conductivity is improved.

According to the manufacturing method of the present invention described above, by the coprecipitation method, an ultrafine synthetic powder having a uniform particle size distribution of 50 nm or less is formed, and the ultrafine synthetic powder has a high sintering driving force and has a high density with excellent densification. A target (oxide sintered compact) can be manufactured. Specifically, a target having a density of 95% or more, preferably 98% or more of the theoretical density measured by the Archimedes method can be produced. In addition, after sintering after synthesis by coprecipitation, phase separation by high temperature does not occur, so that cracks or nodules do not occur during deposition (sputtering) and a uniform conductive film is formed. In addition, a target having a thermal resistivity of 1 × 10 ⁻³ Pa · cm or less, preferably 5 × 10 ⁻⁴ Pa · cm or less, having thermal and chemical stability and excellent electrical conductivity may be prepared.

The target according to the present invention is usefully used as a material for forming a transparent conductive film. In addition, the target according to the present invention may be formed on a substrate by a deposition method such as a sputtering method or an ion plasma method to produce a transparent conductive film. At this time, the target according to the present invention is thermally and chemically stable and is usefully applied to the DC sputtering method using high DC power. Specifically, the target according to the present invention has excellent electrical conductivity, so that abnormal discharge, crack generation, and nodule generation are prevented even when high voltage is applied by the DC sputtering method. Accordingly, the target according to the present invention can be usefully applied to the DC sputtering method having an advantage in the film forming speed, productivity and manufacturing cost, it is possible to produce a low-cost transparent conductive film and a product containing the same.

On the other hand, the transparent conductive film which concerns on this invention contains the oxide composition represented by the said general formula. Specifically, the transparent conductive film according to the present invention is formed by forming the target of the present invention as described above.

Hereinafter, the Example and comparative example of this invention are illustrated. The following examples are merely provided to aid the understanding of the present invention, whereby the technical scope of the present invention is not limited.

Example 1

Zinc nitrate (Zn (NO ₃ ) ₂ ) was mixed in an indium nitrate (In (NO ₃ ) ₃ ) solution so that the content of zinc oxide was 10% by weight, and ultrapure water was added and stirred at 50 ° C. for 12 hours to obtain a pH of 3 Phosphorus In / Zn mixed salt solution was obtained. Subsequently, an aqueous solution of NH ₃ OH was added to the mixed salt solution to pH 9, and then reacted at 40 ° C. for 20 hours to prepare an In / Zn synthetic hydroxide precipitate. The precipitate was separated by filtration, washed three times with ultrapure water, and then dried with hot air at 120 ° C. A particle size photograph of the dried powder is shown in FIG. 2. As shown in Figure 2, the powder by coprecipitation was found to have a uniform particle size distribution of 10 ~ 30nm. Next, the dried powder was put into an electric furnace and heat-treated (calcined) at a temperature of 750 ° C. for 2 hours to obtain an In—Zn—O synthetic oxide powder. A particle size distribution diagram of the In—Zn—O synthetic oxide powder obtained by heat treatment as described above is shown in FIG. 3. As shown in FIG. 3, the In—Zn—O synthetic oxide powder was found to have a uniform particle size distribution of 1 to 5 μm as fine particles of 20 μm or less. In addition, the specific surface area of the In-Zn-O synthetic oxide powder measured by BET method was found to be 17 m 2 / g.

Next, the In-Zn-O synthetic oxide powder was placed in a pot and wet ball mill pulverized with water as a medium. At this time, the shredding medium used a YTZ ball, and during grinding, a binder (polyvinyl alcohol) was added to the pot to grind / mix, and the grind / mix was performed for 20 hours. At this time, as a result of the grinding for 20 hours, it can be seen that the powder has an average particle size distribution of 0.5 ~ 1.0㎛, 90% or more was found to have a particle size distribution of 1.0㎛ or less. Thereafter, the mixed slurry was spray dried to obtain a spherical powder having a diameter of 50 to 80 μm, and a molded body having a predetermined shape (see FIG. 4) was prepared by applying a pressure of 2.5 ton / cm 2 using CIP. Thereafter, the molded body was charged with electricity, and then heated to 1450 ° C at a temperature increase rate of 1.2 ° C / mim, and then sintered by maintaining for 12 hours. At this time, the electric furnace was supplied with 400 L of nitrogen per 1 m 3 of the internal volume to maintain the interior of the electric furnace in a reducing atmosphere, and then cooled, while 200 L of nitrogen per 1 m 3 was added to the electric furnace and allowed to cool. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. A photo of the sputtering target thus produced is shown in FIG. 5. The target (sintered body) prepared according to the present example had a crystal structure of oxygen deficient In ₂ O _3-α (ZnO _1-β ) _γ and had a very dark green color as shown in FIG. 5. Could know.

As a result of measuring the density of the target (sintered body) manufactured as described above, it was found that it was 6.88 g / cm 3 corresponding to 98% of the relative density measured by the Archimedes method, and the surface resistivity was measured as 2.9 x 10 ^-4. It was found that it was Ω · cm.

Example 2

A molded article was prepared in the same manner as in Example 1, and then charged into an electric furnace, and then heated to 1450 ° C. at a temperature rising rate of 1.2 ° C./mim, followed by sintering for 12 hours. In this case, the electric furnace was supplied with 300 L of nitrogen per 1 m 3 of the internal volume to maintain the inside of the electric furnace in a reducing atmosphere. After cooling, 200 L of nitrogen per 1 m 3 was added to the electric furnace and allowed to cool. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. The target (sintered body) prepared according to the present example had a crystal structure of oxygen deficient In ₂ O _3-α (ZnO _1-β ) _γ and had a dark green color.

As a result of measuring the density of the target (sintered body) prepared as described above, it was found that it was 6.89 g / cm3 corresponding to 98.3% of the relative density measured by the Archimedes method, and the surface resistivity was measured 3.2 x 10 ^-4 It was found that it was Ω · cm.

Example 3

Example 1 and the composite powder obtained in the same manner and then, by the synthetic powder with a hydrogen / nitrogen (1/3) holding the gas 750 ℃, 3 hours in a vacuum furnace, an oxygen deficit is In ₂ O ₃ A powder having a crystal structure of _-α (ZnO _1-β ) _γ was obtained. Subsequently, under the same conditions as in Example 1, the slurry was pulverized / mixed for 15 hours by spray drying to obtain a spherical powder of 50 ~ 80㎛. Next, a molded article having a predetermined shape (see FIG. 4) was prepared by applying a pressure of 2.5 ton / cm 2 using CIP. Thereafter, the molded body was put into an electric furnace, and then heated to 1450 ° C. at a temperature rising rate of 1.2 ° C./mim, and then sintered by maintaining for 12 hours. At this time, the electric furnace was supplied with 400 L of nitrogen per 1 m 3 of the internal volume, and the inside of the electric furnace was configured as a reducing atmosphere. After cooling, 200 L of nitrogen per 1 m 3 was added to the electric furnace and cooled. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. The target (sintered body) prepared according to this example had a crystal structure of oxygen deficient In ₂ O _3-α (ZnO _1-β ) _γ and it was found that it had the same very dark green color as in Example 1. Could.

The target prepared as described above (for the sintered body, it was found that the result of measuring the density was 6.85g / ㎠, and the surface resistivity was measured, it was found that 4.5 x 10 ^-4 Pa.cm.

Example 4

Zinc nitrate (Al (NO ₃ ) ₃ ) was mixed in a zinc nitrate (Zn (NO ₃ ) ₂ ) solution so that the aluminum oxide content was 2% by weight, and the mixture was stirred at 50 ° C. for 12 hours, and the pH was 3.5. A phosphorus Zn / Al mixed salt solution was obtained. Next, after adding NH ₃ OH aqueous solution to the mixed salt solution to pH 9.8, and reacted at 40 ℃ 20 hours to prepare a Zn / Al synthetic hydroxide precipitate. The precipitate was separated, washed three times with ultrapure water, and then dried with hot air at 120 ° C. The dried powder was found to have a uniform particle size distribution of 30 ~ 50nm. Next, the dried powder was put into an electric furnace and heat-treated (calcined) at a temperature of 700 ° C. for 2 hours to obtain a Zn-Al-O synthetic oxide powder. The Al-Zn-O synthetic oxide powder thus obtained was found to have a uniform particle size distribution of 5 ~ 10㎛. In addition, it was found that the Al-Zn-O synthetic oxide powder was 11.5 m 2 / g as a result of measuring the specific surface area by the BET method.

Next, the Al-Zn-O synthetic oxide powder was placed in a pot and wet ball mill pulverized with water as a medium. At this time, the shredding medium used a YTZ ball, and during grinding, a binder (polyvinyl alcohol) was added to the pot to grind / mix, and the grind / mix was performed for 20 hours. At this time, as a result of the grinding for 20 hours, it was found that the powder has an average particle size distribution of 0.6 ~ 1.0㎛, 90% or more was found to have a particle size distribution of 1.0㎛ or less. Thereafter, the mixed slurry was spray dried to obtain a spherical powder having a diameter of 40 to 70 μm, and a molded body having a predetermined shape was prepared by applying a pressure of 2.5 ton / cm 2 using CIP. Thereafter, the molded body was charged with electricity, and then heated to 1350 ° C at a temperature increase rate of 1.2 ° C / mim, and then sintered by maintaining for 12 hours. At this time, the electric furnace was supplied with 400 L of nitrogen per 1 m 3 of the internal volume to maintain the inside of the electric furnace in a reducing atmosphere, and after cooling, 200 L of nitrogen per 1 m 3 was added to the electric furnace and cooled. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. A photo of the sputtering target thus produced is shown in FIG. 6. The target (sintered body) prepared according to the present example had a crystal structure of ZnO _{1 -α} (Al ₂ O _{3 -β} ) _γ lacking oxygen and had a very dark blue color as shown in FIG. 6. Could know.

As a result of measuring the density of the target prepared as described above (the sintered body was found to be 5.70 g / cm 3, which corresponds to 99.3% of the relative density measured by the Archimedes method, and the surface resistivity was measured 4.7 x 10 ^-4 Ω. It was found that it was cm.

Example 5

Gallium nitrate (Ga (NO ₃ ) ₃ ) was mixed with zinc nitrate (Zn (NO ₃ ) ₂ ) solution so that the content of gallium oxide was 3% by weight. A phosphorus Zn / Ga mixed salt solution was obtained. Subsequently, NH ₃ OH aqueous solution was added to the mixed salt solution to pH 9.8, and then reacted at 40 ° C. for 20 hours to prepare a Zn / Ga synthetic hydroxide precipitate. The precipitate was separated, washed three times with ultrapure water, and then dried with hot air at 120 ° C. The dried powder was found to have a uniform particle size distribution of 30 ~ 50nm. Next, the dried powder was put into an electric furnace and subjected to heat treatment (calcination) at a temperature of 700 ° C. for 2 hours to obtain a Ga—Zn—O synthetic oxide powder. The Ga-Zn-O synthetic oxide powder obtained by heat treatment as described above has a uniform particle size distribution of 2 to 10 µm. In addition, it was found that the Ga-Zn-O synthetic oxide powder was 13.5 m 2 / g as a result of measuring the specific surface area by the BET method.

Next, the Ga-Zn-O synthetic oxide powder was placed in a pot and wet ball mill pulverized using water as a medium. At this time, the shredding medium used a YTZ ball, and when grinding, a binder (polyvinyl alcohol) was added to the pot together to grind / mix, and the grind / mix was performed for 15 hours. At this time, as a result of the grinding for 15 hours, it was found that the powder has an average particle size distribution of 0.6 ~ 1.0㎛. Thereafter, the mixed slurry was spray dried to obtain a spherical powder having a diameter of 40 to 70 μm, and a molded body having a predetermined shape was prepared by applying a pressure of 2.5 ton / cm 2 using CIP. Thereafter, the molded body was charged with electricity, and then heated to 1450 ° C at a temperature increase rate of 1.2 ° C / mim, and then sintered by maintaining for 12 hours. At this time, the electric furnace was supplied with 400 L of nitrogen per 1 m 3 of the internal volume to maintain the inside of the electric furnace in a reducing atmosphere, and after cooling, 200 L of nitrogen per 1 m 3 was added to the electric furnace and cooled. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. A photo of the sputtering target thus produced is shown in FIG. 7. The target (sintered body) prepared according to the present example had a crystal structure of ZnO _{1 -α} (Ga ₂ O _{3 -β} ) _γ deficient in oxygen, and as shown in FIG. there was.

As a result of measuring the density of the target prepared as described above (the sintered body was found to be 5.51 g / cm 3 corresponding to 98% of the relative density measured by the Archimedes method, and the surface resistivity was measured to be 4.29 x 10 ^{-4 4} It was found that it was cm.

Comparative Example 1

After the molded product was obtained in the same manner as in Example 1, the molded product was put into an electric furnace. Then, the temperature was raised to 1450 ° C. at a temperature rising rate of 1.2 ° C./mim, and then sintered while maintaining for 12 hours. At this time, the electric furnace was supplied with 400 L of oxygen per 1 m 3 of the internal volume to maintain the inside of the electric furnace in an oxidizing atmosphere. After cooling, 200 L oxygen per 1 m 3 of volume was put into the electric furnace and allowed to cool. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. A photo of the sputtering target thus produced is shown in FIG. 5. The target (sintered body) prepared according to the comparative example had a crystal structure of In ₂ O ₃ (ZnO) _γ , and as shown in FIG. 5, light green (light green) color and transparency were seen. there was.

As a result of measuring the density of the target (sintered body) prepared as described above, it was found that it was 6.95 g / cm 3 corresponding to 99.1% of the relative density measured by the Archimedes method, and the surface resistivity was measured as 6.3 x 10 ^-4. It was found that it was Ω · cm.

Comparative Example 2

The same process as in Comparative Example 1 was carried out, but the sintering furnace was sintered at 1250 ° C for 5 hours. The target (sintered body) prepared according to the present comparative example had a crystal structure of In ₂ O ₃ (ZnO) _γ and was found to have a dark green color.

As a result of measuring the density of the target (sintered body) prepared as described above, it was found that it was 6.88 g / cm 3, and it was found that the surface resistivity was measured to be 4.7 × 10 ⁻⁴ Pa · cm.

Comparative Example 3

The same molded article as in Example 4 was put into an electric furnace, heated to 1350 ° C. at a temperature rising rate of 1.2 ° C./mim, and then held for 12 hours to sinter. At this time, the electric furnace was supplied with 400 L of oxygen per 1 m 3 of the internal volume to maintain the inside of the electric furnace in an oxidizing atmosphere. After cooling, 200 L of oxygen per 1 m 3 was added to the electric furnace and allowed to cool. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. A photo of the sputtering target thus produced is shown in FIG. 6. The target (sintered body) prepared in this comparative example had a crystal structure of ZnO (Al ₂ O ₃ ) _γ , and it was found that it had a light green color as shown in FIG. 6.

As a result of measuring the density of the target (sintered body) prepared as described above, it was found that it was 5.51 g / cm 3 corresponding to 98.2% of the relative density measured by the Archimedes method, and the surface resistivity was measured as 1.1 x 10 ^-3. It was found that it was Ω · cm.

[Comparative Example 4]

The same molded article as in Example 5 was put into an electric furnace, heated to 1450 ° C. at a temperature rising rate of 1.2 ° C./mim, and then held for 12 hours and sintered. At this time, the electric furnace was supplied with 400 L of oxygen per 1 m 3 of the internal volume to maintain the inside of the electric furnace in an oxidizing atmosphere. After cooling, 200 L of oxygen per 1 m 3 was added to the electric furnace and allowed to cool. The sintered body obtained through the above process was prepared through the grinding and cutting process to produce a sputtering target. A photo of the sputtering target thus produced is shown in FIG. 7. The target (sintered body) prepared in this Comparative Example had a crystal structure of ZnO (Ga ₂ O ₃ ) _γ , and it was found to have a dark green color as shown in FIG. 7.

As a result of measuring the density of the target (sintered body) prepared as described above, it was found that 5.52 g / cm 3 corresponding to 98.2% of the relative density measured by the Archimedes method, and the surface resistivity was measured 9.7 x 10 ^-4. It was found that it was Ω · cm.

The above results are shown in the following [Table 1]. FIG. 8 shows XRD pattern results of the sintered bodies prepared by Examples 1 and 3 of the present invention, and FIG. 8 shows that XRD peaks are shifted due to lattice structure change due to oxygen deficiency.

             <Comparison of physical property results of manufactured targets> Remarks color Density [g / cm 3] Target Specific Resistance [Ω · cm] Example 1 Very dark green 6.88 2.9 x 10 ^-4 Example 2 Dark green 6.89 3.2 x 10 ^-4 Example 3 Dark green 6.85 4.5 x 10 ^-4 Example 4 Dark green 5.70 4.7 x 10 ^-4 Example 5 Dark green 5.51 4.29 x 10 ^-4 Comparative Example 1 Transparent pale green 6.95 6.3 x 10 ^-4 Comparative Example 2 Dark green 6.88 4.7 x 10 ^-4 Comparative Example 3 Light green 5.51 1.1 x 10 ^-3 Comparative Example 4 Dark green 5.52 9.7 x 10 ^-4

As shown in Table 1, it was found that the embodiment according to the present invention had a high density. In addition, it can be seen that it has excellent electrical conductivity because the specific resistance is lower than in the case of oxygen-deficient structure (example), otherwise (comparative example).

1 is a manufacturing process diagram of the present invention.

2 is a particle size photograph of a dried powder according to Example 1 of the present invention.

3 is a particle size distribution diagram of a synthetic oxide powder according to Example 1 of the present invention.

Figure 4 is a photograph of the molded article produced by Examples 1 and 3 of the present invention.

5 is a photograph of the target prepared by Example 1 and Comparative Example 1 of the present invention.

6 is a photograph of a target prepared by Example 4 and Comparative Example 3 of the present invention.

7 is a photograph of the target prepared by Example 5 and Comparative Example 4 of the present invention.

8 is an XRD pattern result of the sintered body prepared by Examples 1 and 3 of the present invention.

Claims (16)

delete delete delete delete delete delete A first step of obtaining a metal salt solution having a pH of 1 to 4 by adding a pH adjusting agent to a solution containing two or more different metal salts; A second step of adding alkali to the metal salt solution of the first step so as to have a pH of 7 to 10 and then maintaining a 10 to 80 ° C. to obtain a metal hydroxide precipitate; A third step of drying the precipitate of the second step to obtain a metal hydroxide powder; A fourth step of obtaining the metal oxide powder by heat-treating the metal hydroxide powder of the third step at 500 to 800 ° C .; A fifth step of grinding the metal oxide powder of the fourth step; A sixth step of manufacturing a molded body using the powder of the fifth step; A seventh step of sintering the molded body of the sixth step; And And an eighth step of cooling the sintered body of the seventh step. The method of claim 7, wherein The second step of obtaining the metal hydroxide precipitate is a method for producing an oxide-based target for a transparent conductive film, characterized in that for 10 to 40 hours at a temperature of 10 ~ 80 ℃. The method of claim 7, wherein The metal oxide powder obtained in the fourth step has a mean particle size of 1.0 to 10.0 μm, characterized in that the method for producing an oxide-based target for a transparent conductive film. The method according to claim 7 or 9, The metal oxide powder obtained in the fourth step has a specific surface area of 10 to 30 m 2 / g. The method of claim 7, wherein The sintering of the seventh step comprises the step of maintaining the oxygen concentration in the sintering furnace lower than the oxygen concentration in the atmosphere and sintering, characterized in that the manufacturing method of the oxide-based target for a transparent conductive film. The method of claim 7, wherein The sintering of the seventh step, the first step of raising the temperature inside the sintering furnace to 900 ℃ in the oxygen atmosphere, and the second sintering by maintaining the oxygen concentration lower than the oxygen concentration in the atmosphere and raising the temperature above 1000 ℃ A process for producing an oxide-based target for a transparent conductive film, comprising the step. The method of claim 12, The second step is maintained in a reducing or inert atmosphere of 200 ~ 500L per 1.0㎥ of the internal volume of the sintering furnace, and proceeds for 10 to 20 hours at a temperature of 1250 ~ 1550 ℃ of the oxide-based target for transparent conductive film Manufacturing method. The method of claim 7, wherein The cooling of the eighth step is performed by maintaining the oxygen concentration in the sintering furnace equal to the oxygen concentration in the atmosphere or lower than the oxygen concentration in the atmosphere. delete delete

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