JP5224073B2 - Oxide deposition material and method for producing the same - Google Patents

Description

The present invention relates to an oxide vapor deposition material used when producing a transparent conductive film by various vacuum vapor deposition methods such as an electron beam vapor deposition method, an ion plating method and a high density plasma assisted vapor deposition method, and a production method thereof , for example, The present invention relates to an improvement in an oxide vapor deposition material used for producing a transparent conductive film having a low resistance and a high transmittance in the visible region, which is useful as a transparent electrode of a solar cell.

  The transparent conductive film has high conductivity and high light transmittance in the visible light region. And taking advantage of this characteristic, the transparent conductive film is used for electrodes of solar cells, liquid crystal display elements, other various light receiving elements, etc., and further, utilizing the reflection / absorption characteristic in the near infrared region, it can be used for automobiles and buildings. It is also used as a heat-reflective film used for window glass, various antistatic films, and a transparent heating element for anti-fogging such as a frozen showcase.

The transparent conductive film generally has tin oxide (SnO ₂ ) containing antimony or fluorine as a dopant, aluminum, gallium, indium, zinc oxide (ZnO) containing tin as a dopant, tin, tungsten or titanium as a dopant. Indium oxide (In ₂ O ₃ ) and the like are widely used. In particular, an indium oxide film containing tin as a dopant, that is, an In ₂ O ₃ —Sn-based film is called an ITO (Indium tin oxide) film, and since a low-resistance transparent conductive film can be easily obtained, it has been industrially used so far. Widely used.

  And as a manufacturing method of these transparent conductive films, the vacuum evaporation method, sputtering method, the method of apply | coating the coating liquid for transparent conductive layer formation, etc. are generally used. Among them, the vacuum vapor deposition method and the sputtering method are effective methods when using a material having a low vapor pressure or when precise film thickness control is required, and because the operation is very simple, Is useful. Further, when the vacuum deposition method and the sputtering method are compared, the vacuum deposition method is superior in mass productivity because it can form a film at a higher speed.

By the way, in the vacuum deposition method, in general, in a vacuum of about 10 ⁻³ to 10 ⁻² Pa, a solid or liquid as an evaporation source is heated to be decomposed once into gas molecules and atoms, and then again on the substrate surface. It is a method of condensing as a thin film. Further, although there are various heating methods for the evaporation source, a resistance heating method (RH method) and an electron beam heating method (EB method, electron beam evaporation method) are common. A reactive vapor deposition method is also well known in which vapor deposition is performed while introducing a reactive gas such as O ₂ gas into a film forming chamber (chamber).

In the case of depositing an oxide film such as ITO, the electron beam evaporation method has been used historically. That is, an ITO oxide vapor deposition material (also referred to as an ITO tablet or an ITO pellet) is used as an evaporation source, an O ₂ gas as a reaction gas is introduced into a film forming chamber (chamber), and a thermoelectron generating filament (mainly W When the thermal electrons emitted from the line) are accelerated by an electric field and irradiated onto the ITO oxide vapor deposition material, the irradiated portion becomes locally high in temperature and evaporated to be deposited on the substrate. In addition, it is possible to produce a low-resistance film on a low-temperature substrate by generating plasma using a thermionic emitter or RF discharge and activating evaporates and reactive gases (O ₂ gas etc.) with this plasma. An activated reactive vapor deposition method (ARE method) that can be used is also a useful method for forming an ITO film. Furthermore, recently, it has become clear that a high-density plasma-assisted vapor deposition method (HDPE method) using a plasma gun is also an effective method for forming an ITO film, and has begun to be widely used industrially (see Non-Patent Document 1). . In this method, arc discharge using a plasma generator (plasma gun) is used, but arc discharge is maintained between a cathode built in the plasma gun and a crucible (anode) of an evaporation source. Electrons emitted from the cathode are guided (guided) by a magnetic field and are concentrated and irradiated on the local area of the ITO oxide deposition material charged in the crucible. The evaporated material is evaporated and deposited on the substrate from the portion where the electron beam is irradiated and locally heated. Since the evaporated vapor and the introduced O ₂ gas are activated in this plasma, an ITO film having good electrical characteristics can be produced. Further, as another classification method of these various vacuum deposition methods, those accompanied by ionization of evaporates and reaction gases are collectively referred to as an ion plating method (IP method), and ITO with low resistance and high light transmittance is used. It is effective as a method for obtaining a film (see Non-Patent Document 2).

  By the way, in any type of solar cell to which a transparent conductive film is applied, the transparent conductive film is indispensable for the front-side electrode that is exposed to light. Conventionally, the above-described ITO film, aluminum, and gallium are doped. Zinc oxide (ZnO) films have been utilized. These transparent conductive films are required to have characteristics such as low resistance and high light transmittance of sunlight. Further, as a method for producing these transparent conductive films, vacuum deposition methods such as the above-described ion plating method and high-density plasma assist deposition method are used.

  The oxide deposition material used in the vacuum deposition methods such as the electron beam deposition method, ion plating method, and high density plasma assisted deposition method has a small size (for example, a diameter of 10 to 50 mm and a height of about 10 to 50 mm). Therefore, there is a limit to the amount of film that can be formed with one oxide vapor deposition material. Then, when the consumption amount of the oxide vapor deposition material increases and the remaining amount decreases, the film formation is interrupted, the vacuum film formation chamber is introduced into the atmosphere and replaced with an unused oxide vapor deposition material, and the film is formed. It was necessary to evacuate the chamber again, which caused productivity to deteriorate.

  Therefore, a continuous supply method of the above-mentioned oxide deposition material is cited as an indispensable technique for mass production of transparent conductive films by vacuum deposition methods such as electron beam deposition, ion plating, and high density plasma assisted deposition. One example is described in Non-Patent Document 1. In this continuous supply method, columnar oxide vapor deposition materials are continuously stored inside a cylindrical hearth, and the oxide vapor deposition materials are sequentially extruded while maintaining the height of the sublimation surface constant. It comes to be supplied. And the mass production of the transparent conductive film by a vacuum evaporation method came to be realizable by the continuous supply method of an oxide vapor deposition material.

And regarding the oxide vapor deposition material used as a raw material, in patent document 1, the vapor deposition material of ITO is introduced. It is substantially an In ₂ O ₃ —SnO ₂ type particle composed of indium, tin and oxygen, and the volume of one particle is 0.01 to 0.5 cm ³ and the relative density is 55% or more. Further, an ITO vapor deposition material having a bulk density of 2.5 g / cm ³ or less when filled in a container has been proposed. With the above configuration, an ITO evaporation material that can stably form a low-resistance ITO film by electron beam evaporation, has a utilization efficiency of 80% or more, and can be continuously supplied without clogging in the supply machine. Is obtained.

Further, Patent Document 2 also introduces an ITO vapor deposition material made of indium oxide and tin oxide. The ITO vapor deposition material described in Patent Document 2 is composed of a cylindrical oxide sintered body having a density of 4.9 g / cm ³ , a diameter of 30 mm, and a thickness of 40 mm, and is continuous without being damaged in the feeder. It is stated that supply is possible.

JP-A-8-104978 (see claims, paragraphs 0009 and 0017) JP 2007-84881 A (see claims, paragraph 0007, paragraph 0091, paragraph 0108)

`` Vacuum '', Vol.44, No.4, 2001, p.435-439 "Technology of transparent conductive film", Ohmsha, 1999, p. 205-211

  By the way, by using various conventional vacuum evaporation methods such as an electron beam evaporation method, an ion plating method, and a high density plasma assisted evaporation method using a conventional ITO evaporation material (oxide evaporation material) described in the above-mentioned patent documents, etc. In the case of manufacturing a transparent conductive film having high light transmittance with resistance, it is necessary to introduce a large amount of oxygen gas into a film formation vacuum chamber during film formation (see, for example, description in paragraphs 0007 and 0108 of Patent Document 2). Therefore, the following problems arise mainly.

  First, the composition deviation of a transparent conductive film and an oxide vapor deposition material becomes large, and the composition design of a transparent conductive film becomes difficult. This is because, generally, when the amount of oxygen introduced into the film-forming vacuum chamber increases, the difference in composition between the transparent conductive film and the oxide vapor deposition material tends to increase. In the film formation mass production process, the amount of oxygen in the film formation vacuum chamber is likely to fluctuate. Therefore, the film composition is likely to fluctuate due to the influence thereof, leading to variations in film characteristics.

  In reactive vapor deposition using oxygen gas, when the amount of oxygen increases, not only the density of the film decreases, but also the adhesion of the film to the substrate weakens. This is because if the evaporated metal oxide is oxidized before reaching the substrate, energy is lost, and if the rate of oxidation increases, it becomes difficult to obtain a dense and highly adhesive film with respect to the substrate.

  Furthermore, when a transparent conductive film is formed on a substrate covered with a metal film or organic film whose surface is easily oxidized, if there is a large amount of oxygen gas to the film formation vacuum chamber, the substrate surface will be oxidized before film formation. As a result, high-performance devices cannot be manufactured. This tendency becomes more prominent as the substrate temperature during film formation is higher. For example, when manufacturing a solar cell that converts energy by making light incident from the surface opposite to the substrate, it is necessary to form a transparent conductive film on the PIN element formed of a metal thin film. If a large amount of film is formed, the element is easily damaged and a high-performance device cannot be manufactured. The same applies to the formation of organic thin-film solar cells and top-emission type organic electroluminescence elements. When a transparent conductive film is formed on an organic light-emitting layer, the organic light-emitting layer is oxidized under conditions where a large amount of oxygen is introduced. Therefore, a high-performance element cannot be realized.

The present invention has been made paying attention to such problems, and the problem is that the main component is indium oxide to which tin is added, and even if the amount of oxygen introduced at the time of film formation is small, low resistance is achieved. It is another object of the present invention to provide an oxide vapor deposition material capable of stably producing a transparent conductive film having high light transmittance in the visible region, and to provide a method for producing this oxide vapor deposition material.

That is, the invention according to claim 1
In the oxide vapor deposition material used when producing a transparent conductive film by vacuum vapor deposition,
The main component is indium oxide, tin is included, and the oxide sintered body is manufactured by an atmospheric pressure sintering method. The tin content is 0.001 to 0.00 in terms of the Sn / In atomic ratio. 614, and the L ^* value in the CIE 1976 color system is 54 to 75,
The invention according to claim 2
In the oxide vapor deposition material according to claim 1,
Content of the said tin is 0.040-0.163 by Sn / In atomic ratio, It is characterized by the above-mentioned.

The invention according to claim 3
In the oxide vapor deposition material according to claim 1,
The above oxide sintered body is manufactured by an atmospheric pressure sintering method in which oxygen is burned at a temperature of 1150 to 1300 ° C. while introducing oxygen at a rate of 5 liters / minute or more per 0.1 m ^{3 of} the furnace volume . It is characterized by
The invention according to claim 4
In the manufacturing method of the oxide vapor deposition material of Claim 1,
Using each powder of indium oxide and tin oxide as raw materials, mixing so that the tin content is 0.001 to 0.614 in the Sn / In atomic ratio, and granulating to obtain a granulated powder, A molded body preparation step for molding the obtained granulated powder;
After performing the binder removal treatment at a temperature of 300 to 500 ° C. to the shaped body while introducing oxygen percentage in volume 0.1 m ³ per 5 liters / minute or more furnace into the furnace, furnace capacity 0.1 m ³ A debinding and baking step of performing a baking treatment at a temperature of 1150 to 1300 ° C. while introducing oxygen at a rate of 5 liters / minute or more into the furnace,
The oxygen and argon mixing ratio (volume ratio) is in the range of O ₂ / Ar = 40/60 to 90/10, and oxygen at a rate of 5 liters / minute or more per 0.1 m ^{3 of} the furnace volume An oxygen amount adjusting step for adjusting the oxygen amount for 10 hours or more at a temperature of 900 to 1100 ° C. with respect to the sintered body while introducing a mixed gas of argon into the furnace;
It comprises each of these processes.

The oxide vapor deposition material according to the present invention is composed of an oxide sintered body containing indium oxide as a main component and containing tin, and the tin content is 0.001 to 0.614 in terms of the Sn / In atomic ratio. The L ^* value in the CIE 1976 color system is 54 to 75.

Since the oxide vapor deposition material according to the present invention having an L ^* value of 54 to 75 in the CIE 1976 color system has an optimum oxygen amount, a film formation vacuum can be obtained by applying this oxide vapor deposition material. Even if the amount of oxygen gas introduced into the tank is small, it is possible to produce a transparent conductive film with low resistance and high transparency in the visible region by the vacuum deposition method, and the amount of oxygen gas introduced into the film forming vacuum tank Therefore, it is possible to reduce the difference in composition between the film and the oxide vapor deposition material, making it easy to obtain the desired film composition, as well as reducing fluctuations in film composition and characteristics during mass production. It becomes. In addition, since film formation with a small amount of oxygen gas introduced into the film formation vacuum chamber can reduce damage to the substrate due to oxygen gas, a high-performance device can be realized. In particular, a high-performance film useful for solar cells can be stably produced without damaging the substrate.

(1) Oxide vapor deposition material The oxide vapor deposition material of the present invention has a composition in which indium oxide is a main component and tin is contained at a ratio of 0.001 to 0.614 in terms of the Sn / In atomic ratio. . And since the composition of the transparent conductive film manufactured by the vacuum evaporation method using the oxide vapor deposition material of the present invention is very close to the composition of the oxide vapor deposition material, the film composition to be manufactured is also composed mainly of indium oxide. And it becomes the composition which tin contains only the ratio of 0.001-0.614 by Sn / In atomic ratio. The reason why tin is contained in the above proportion is that the mobility of the indium oxide film can be increased. When the film composition, that is, the tin content (Sn / In atomic ratio) of the oxide vapor deposition material composition is less than 0.001, the effect of increasing the carrier concentration (that is, the effect of increasing the mobility) is small and a low resistance film is obtained. I can't. On the other hand, if it exceeds 0.614, the amount of tin in the film is too large, and the scattering of neutral impurities during electron transfer becomes large, and the mobility is lowered, resulting in a low resistance film. I can't. A more preferable tin content for exhibiting a higher carrier concentration to obtain a low resistance film is 0.040 to 0.163 in terms of the Sn / In atomic ratio, and the film is a crystal film. It is.

  By the way, the transparent conductive film containing indium oxide as a main component is an n-type semiconductor, but an appropriate oxygen deficiency is required in order to exhibit high conductivity and high light transmittance. That is, when the amount of oxygen in the film is large and the amount of oxygen vacancies is small, even if it contains a dopant, it does not exhibit conductivity. In order to exhibit conductivity, it is necessary to introduce oxygen vacancies into the film. However, if the amount of oxygen vacancies is too large, light absorption of visible light increases, which causes coloring. Therefore, the film needs to have an optimal oxygen deficiency. Oxygen in the film is supplied not only from the oxide vapor deposition material as a raw material but also by oxygen gas introduced into the film formation vacuum chamber during film formation being taken into the film. And if there is little supply from an oxide vapor deposition material, it is necessary to increase the amount of oxygen gas introduced into the film-forming vacuum chamber, but as described above, the amount of oxygen gas introduced into the film-forming vacuum chamber is increased. Problems arise. Therefore, an oxide vapor deposition material having an optimal oxygen amount is useful.

And, the oxide vapor deposition material according to the present invention is characterized in that it is defined by the L ^* value in the CIE 1976 color system. Here, the CIE 1976 color system is a color space recommended by the CIE (International Commission on Illumination) in 1976. Color, lightness L ^* and black Manet ticks indices a ^*, since those expressed in coordinates on a uniform color space of b ^*, are abbreviated as CIELAB. ^{L *} is showing the lightness ^{indicates black,} the diffuse color of white in the L * = 100 in ^L * = 0. Further, a ^* is a negative value for green, a positive value for magenta, b ^* is a negative value for blue, and a positive value for yellow.

And it is preferable that the color of the sintered body surface and the inside of the sintered body of the oxide vapor deposition material according to the present invention defined by the L ^* value in the CIE 1976 color system is the same, but it is temporarily different between the outermost surface and the inside. In the present invention, the L ^* value is determined for the inside of the sintered body.

According to experiments by the inventors, when the L ^* value inside the oxide vapor deposition material is 54 to 75, it has both high conductivity and high transmittance in the visible region even if the amount of oxygen introduced into the deposition vacuum chamber is small. A transparent conductive film can be obtained. Also, the whitish color has a higher L ^* value, while the darker the color, the lower the L ^* value. The L ^* value of the oxide vapor deposition material is considered to have a correlation with the amount of oxygen contained in the oxide vapor deposition material. The larger the L ^* value, the greater the amount of oxygen contained, and the smaller the L ^* value. It is considered that the oxygen content is small. The present inventors have changed the production conditions, was experimented to produce a transparent conductive film by a vacuum deposition method using an oxide evaporation materials of various L ^* values, as L ^* value is large, the film formation The optimum amount of oxygen to be introduced into it (the amount of oxygen for obtaining a film with low resistance and high transparency) was small. This is because the larger the L ^* value, the greater the amount of oxygen supplied from the oxide vapor deposition material itself. Further, the difference in composition between the film and the oxide vapor deposition material tends to increase as the amount of oxygen introduced increases. Therefore, the larger the L ^* value, the smaller the composition difference.

The oxide vapor deposition material according to the present invention has conductivity, and the conductivity of the oxide vapor deposition material depends on the oxygen content, but also on the density, crystal grain size, and tin dopant efficiency. Therefore, the conductivity and L ^* value of the oxide vapor deposition material do not correspond one to one.

And, from the oxide vapor deposition material according to the present invention containing indium oxide as a main component and containing tin, during vacuum deposition, evaporated particles are mainly generated in the form of In ₂ O _3-x and SnO _2-x , Oxygen is absorbed while reacting with oxygen in the chamber and reaches the substrate to form a film. Further, when the evaporated particles reach the substrate and deposit on the substrate, the energy becomes a driving source for mass transfer, contributing to densification of the film and enhancement of adhesion to the substrate. Since the smaller the L ^* value of the oxide vapor deposition material, the less oxygen in the oxide vapor deposition material, the greater the oxygen deficiency of the evaporated particles, so that a large amount of oxygen is introduced into the vacuum chamber before reaching the substrate. It is necessary to increase the rate of oxidation reaction. However, since the evaporated particles consume energy by being oxidized during the flight, it is difficult to obtain a dense film having high adhesion to the substrate in the reactive film in which a large amount of oxygen is introduced. On the contrary, the reactive vapor deposition film forming the oxygen gas to be introduced as much as possible is easier to obtain a highly adherent and high density film, and the oxide vapor deposition material of the present invention can realize this.

Here, when the L ^* value is less than 54, the amount of oxygen in the oxide vapor deposition material is too small, so the optimum amount of oxygen introduced into the film formation vacuum chamber for obtaining a film with low resistance and high transparency. This is not preferable because not only the compositional difference between the film and the oxide vapor deposition material increases, but also problems such as increased damage to the substrate occur during film formation. On the other hand, if the L ^* value exceeds 75, the amount of oxygen contained in the oxide deposition material is too large, and as a result, too much oxygen is supplied from the oxide deposition material to the film. It is impossible to obtain a highly conductive film.

By the way, JP-A-5-112866 (reference gazette) disclosing an invention related to the sputtering method introduces a sputtering target of an indium oxide sintered body containing tin, but is described in the reference gazette. The L ^* value of the indium oxide sintered body containing tin produced according to the production method is a low value of 38 to 49 (see Comparative Example 3). Therefore, when such a sintered body is used as an oxide vapor deposition material, it is necessary to increase the amount of oxygen introduced into a film formation vacuum chamber for obtaining an optimum film, and thus the above-described problem occurs. Therefore, the object of the present invention has not been achieved.

Here, the oxide sintered body for vapor deposition (oxide vapor deposition material) of the present invention having the L ^* value of 54 to 75 cannot be produced by a conventional technique for producing an ITO sintered body. An oxide vapor deposition material having an appropriate amount of oxygen (or oxygen deficiency) suitable for use in mass production by a vacuum vapor deposition method can be produced by the following method.

  That is, an oxide sintered body containing indium oxide as a main component and containing tin is made of indium oxide and tin oxide powders, mixed and molded to form a green compact, and fired at a high temperature. Then, it can be produced by reaction and sintering. Each powder of indium oxide and tin oxide is not special, and may be a conventionally used raw material for an oxide sintered body. Moreover, the average particle diameter of the powder used is 1.5 micrometers or less, Preferably it is 0.1-1.1 micrometers.

  A ball mill mixing method is used as a general raw material powder mixing method for manufacturing the oxide sintered body, but it is also effective in manufacturing the sintered body of the present invention. The ball mill is a device for making a fine mixed powder by grinding and mixing materials by putting a hard ball (ball diameter: 10 to 30 mm) such as ceramic and powder of the material into a container and rotating the container. Ball mills (grinding media) include steel, stainless steel, nylon, etc. as can bodies, and alumina, magnetic material, natural silica, rubber, urethane, etc. are used as linings. Examples of the balls include alumina balls containing alumina as a main component, natural silica, nylon balls with iron core, and zirconia balls. There are wet and dry pulverization methods, and they are widely used for mixing and pulverizing raw material powders to obtain sintered bodies.

  Further, as a method other than the ball mill mixing, a bead mill method or a jet mill method is also effective. In particular, since tin oxide powder is a hard material, it is very effective when a raw material having a large average particle diameter is used or when it is necessary to pulverize and mix in a short time. In the bead mill method, 70-90% of beads (crushed media, bead diameter: 0.005-3 mm) are filled in a container called a vessel, and the rotation axis at the center of the vessel is set at a peripheral speed of 7-15 m / sec. Giving motion to the beads by rotating. Here, a slurry in which a material to be crushed, such as raw material powder, is mixed with a liquid is fed by a pump and finely pulverized and dispersed by colliding beads. In the case of a bead mill, efficiency can be improved by reducing the bead diameter according to the object to be crushed. In general, a bead mill can achieve pulverization and mixing at an acceleration close to 1,000 times that of a ball mill. The bead mill with such a structure is called by various names. For example, sand grinder, aquamizer, attritor, pearl mill, avex mill, ultra visco mill, dyno mill, agitator mill, coball mill, spike mill, SC mill Etc. are known, and any of them can be used in the present invention. In addition, the jet mill is a method in which high-pressure air or steam injected from a nozzle at around the sonic velocity is collided with an object to be crushed such as raw material powder as an ultra-high speed jet, and pulverized into fine particles by impact between particles. .

  As described above, first, indium oxide powder and tin oxide powder are put into a ball mill pot at a desired ratio, and mixed powder is prepared by dry or wet mixing. And in order to obtain the oxide sintered compact of this invention, it prepares so that content of an indium and tin may become 0.001-0.614 by Sn / In atomic ratio about the mixture ratio of the said raw material powder. To do.

  A slurry is produced by adding water and an organic substance such as a dispersing agent / binder to the mixed powder thus prepared. The viscosity of the slurry is preferably 150 to 5000 cP, more preferably 400 to 3000 cP.

  A granulated powder can be obtained by drying the slurry thus obtained with a spray dryer or the like. However, in order to obtain a sintered body that is more uniform and has good sinterability, it is more effective to perform pulverization and mixing with the following bead mill.

  That is, the obtained slurry and beads are placed in a bead mill container and pulverized and mixed. Examples of the bead material include zirconia and alumina. Zirconia is preferable in terms of wear resistance. The diameter of the beads is preferably 1 to 3 mm from the viewpoint of grinding efficiency. The number of passes may be one, but it is preferably two or more, and a sufficient effect can be obtained by five or less. Moreover, as processing time, Preferably it is 10 hours or less, More preferably, it is 4 to 8 hours.

  By performing such treatment, the pulverization and mixing of the indium oxide powder and the tin oxide powder in the slurry are improved.

Next, it shape | molds using the slurry processed in this way. As the molding method, either a cast molding method or a press molding method can be employed. When cast molding is performed, the obtained slurry is injected into a casting mold to produce a molded body. The time from bead mill treatment to casting is preferably within 10 hours. It is because it can prevent that the slurry obtained by doing in this way shows thixotropic property. Moreover, when performing press molding, binders, such as polyvinyl alcohol, are added to the obtained slurry, moisture adjustment is performed as needed, and it is dried with a spray dryer etc. and granulated. The obtained granulated powder is filled into a mold having a predetermined size, and then subjected to uniaxial pressure molding at a pressure of 9.8 to 98 MPa (100 to 1000 kg / cm ² ) using a press machine. And The thickness of the molded body at this time is preferably set to a thickness capable of obtaining a sintered body having a predetermined size in consideration of shrinkage caused by the subsequent firing step.

  If the molded object produced from the above-mentioned mixed powder is used, the oxide sintered compact of this invention can be obtained by a normal pressure sintering method. In addition, when baking by an atmospheric pressure sintering method and obtaining an oxide sintered compact, it is as follows.

First, the obtained molded body is heated at a temperature of 300 to 500 ° C. for about 5 to 20 hours to perform a binder removal treatment. Thereafter, sintering is performed by raising the temperature, but the rate of temperature rise is 150 ° C./hour or less, preferably 100 ° C./hour or less, more preferably 80 ° C., in order to effectively release internal vacancies to the outside. / Hour or less. The sintering temperature is 1150 to 1300 ° C, preferably 1200 to 1250 ° C, and the sintering time is 1 to 20 hours, preferably 2 to 5 hours. It is important that the binder removal process to the sintering process be performed by introducing oxygen into the furnace at a rate of 5 liters / minute or more per 0.1 m ^{3 of} the furnace volume. The reason why oxygen is introduced in the sintering step is to prevent the sintered body from dissociating oxygen at 1150 ° C. or higher and easily proceeding to an excessive reduction state. Once a sintered body into which oxygen deficiency is excessively introduced is formed in this step, it becomes difficult to optimally adjust the oxygen deficiency amount of the sintered body in the subsequent oxygen amount adjusting step. If the calcination temperature is higher than 1300 ° C., oxygen dissociation becomes intense even in the oxygen atmosphere as described above, and it is easy to proceed to an excessive reduction state, which is not preferable for the same reason. Moreover, if the firing temperature is less than 1150 ° C., the temperature is too low and the sintering is poor, and a sintered body with sufficient strength cannot be obtained.

  After sintering, an oxygen content adjusting step of the sintered body is performed. It is important that the oxygen amount adjusting step is performed at a heating temperature of 900 to 1100 ° C., preferably 950 to 1050 ° C., and the heating time is 10 hours or more. Cooling to the heating temperature in the oxygen amount adjusting step is performed while continuing the introduction of oxygen, and the temperature is decreased at a temperature decreasing rate of 0.1 to 20 ° C./min, preferably 2 to 10 ° C./min.

In the process of adjusting the amount of oxygen in the sintered body, it is particularly important to control the atmosphere in the furnace, and the gas introduced into the furnace has a mixing ratio (volume ratio) of oxygen and argon of O ₂ / Ar = 40/60 to 90/10. Therefore, it is important to control the flow rate within a range of 5 liters / minute or more per 0.1 m ^{3 of} the furnace volume. By precisely adjusting the temperature, atmosphere, and time, a sintered body having the L ^* value defined in the present invention, which is useful when used as an oxide deposition material, can be obtained.

When the heating temperature in the oxygen amount adjusting step is less than 900 ° C., the oxygen dissociation / adsorption reaction is slow, and it takes time for uniform reduction treatment to the inside of the sintered body. If it is performed at a temperature, the dissociation of oxygen is too intense, and an optimal reduction treatment in the above atmosphere becomes impossible. Further, if the heating temperature in the oxygen amount adjusting step is less than 10 hours, it is not preferable because uniform reduction treatment cannot be performed to the inside of the sintered body. Further, if the mixing ratio of the gas introduced into the furnace (O ₂ / Ar) is less than 40/60, the reduction due to the dissociation of oxygen becomes too dominant, and the sintered body has an L ^* value of less than 54. Therefore, it is not preferable. On the other hand, if the mixing ratio of the gas introduced into the furnace (O ₂ / Ar) exceeds 90/10, the oxidation becomes too dominant and the sintered body having an L ^* value exceeding 75 is not preferable. .

  In order to obtain the oxide vapor deposition material of the present invention, as described above, annealing treatment is performed in a gas atmosphere in which oxygen gas is precisely diluted with argon gas, that is, in an atmosphere in which the amount of oxygen is precisely controlled. It is important that the atmosphere gas is not necessarily a mixed gas of oxygen and argon. For example, it is effective to use other inert gas such as helium or nitrogen instead of argon. Further, even when the atmosphere is used instead of argon, it is effective if the oxygen content is precisely and constantly controlled in the entire mixed gas. However, it is not effective to introduce oxygen gas into a furnace fired in the atmosphere as in the prior art because the oxygen content of the atmosphere in the furnace cannot be precisely controlled. As proposed in the present invention, an oxide vapor deposition material having an optimal reduced state is obtained by introducing a mixed gas with an inert gas whose oxygen gas content is precisely controlled to fill the furnace. Can be obtained.

  And after finishing an oxygen amount adjustment process, it can cool to room temperature at 10 degree-C / min, and can take out from a furnace at room temperature. The obtained sintered body can be processed into a predetermined dimension by grinding or the like to obtain an oxide vapor deposition material. Also, considering the shrinkage rate of sintering, if a molded body having a predetermined size after firing is used, it can be used as an oxide deposition material without performing grinding after sintering. it can.

Incidentally, it is known that the hot press method is effective as a method for obtaining a high-density sintered body as one of the methods for producing a sputtering target. However, when the hot pressing method is applied to the material of the present invention, only a sintered body having an L ^* value of 40 or less and an excessively strong reducing property can be obtained. With such a sintered body, the object of the present invention cannot be achieved.

  In addition, the oxide vapor deposition material of the present invention can be used, for example, in the form of a cylindrical tablet or pellet having a diameter of 10 to 50 mm and a height of 10 to 50 mm. Such a sintered body is pulverized. It can also be used in the form of granules of about 1 to 10 mm.

  In addition, for the oxide vapor deposition material according to the present invention, even if, for example, tungsten, molybdenum, zinc, cadmium, cerium, or the like is included as an element other than indium, tin, and oxygen, the characteristics of the present invention are impaired. It is allowed on condition that it is not possible. However, among metal ions, when the vapor pressure of the oxide is extremely higher than the vapor pressure of indium oxide or tin oxide, it is difficult to evaporate by various vacuum deposition methods, so it is preferable that the oxide is not contained. For example, metals such as aluminum, titanium, and silicon vaporize together with indium oxide and tin oxide when included in an oxide deposition material because the vapor pressure of these oxides is extremely high compared to indium oxide and tin oxide. It becomes difficult to make it. For this reason, it must not be contained because it remains in the oxide vapor deposition material and has a high concentration and ultimately has an adverse effect on the evaporation of indium oxide and tin oxide.

  And when applying the oxide vapor deposition material of the present invention to produce a transparent conductive film by various vacuum vapor deposition methods, the oxygen content in the oxide vapor deposition material is optimally adjusted. Even if the amount of oxygen introduced is small, an optimal oxygen deficient transparent conductive film can be obtained. Therefore, there is an advantage that the compositional difference between the transparent conductive film and the oxide vapor deposition material is small, and it is difficult to be affected by the characteristic variation accompanying the variation of the oxygen introduction amount.

(2) Transparent conductive film It is composed of an oxide sintered body containing indium oxide as a main component and containing tin, and the tin content is 0.001 to 0.614 in terms of the Sn / In atomic ratio, in the CIE 1976 color system. Applying the oxide vapor deposition material according to the present invention having an L ^* value of 54 to 75, oxidation containing tin is performed by various vacuum vapor deposition methods such as an electron beam vapor deposition method, an ion plating method, and a high density plasma assisted vapor deposition method. An indium crystal film (transparent conductive film) can be manufactured.

  By using a crystalline film, high mobility can be exhibited when tin is substituted and dissolved in the indium sites of indium oxide. The crystal film (transparent conductive film) can be obtained by heating the substrate being formed to 180 ° C. or higher, but the film obtained by non-heating film formation without heating the substrate is annealed at 180 ° C. or higher. It can also be obtained by the method.

And since the said crystalline transparent conductive film can be manufactured from an oxide vapor deposition material with a small composition difference of a film | membrane and an oxide vapor deposition material, 0.001-0.614 tin is contained by Sn / In atomic ratio. An indium oxide film. When the tin content (Sn / In atomic ratio) of the film is less than 0.001, the effect of increasing the carrier concentration (that is, the effect of increasing the mobility) is small and a low resistance film cannot be obtained. On the other hand, if it exceeds 0.614, the amount of tin in the film is too large, and the scattering of neutral impurities during electron transfer becomes large, and the mobility is lowered, resulting in a low resistance film. Absent. In order to obtain a transparent conductive film having a higher carrier concentration, the more preferable tin content is 0.040 to 0.163 in terms of the Sn / In atomic ratio, and the film is a crystalline film. By obtaining a crystal film having such a composition range, a transparent conductive film having a carrier concentration of 7.2 × 10 ²⁰ cm ⁻³ or more and a specific resistance of 3.5 × 10 ⁻⁴ Ωcm or less can be realized. . The transparent conductive film has an extremely high average transmittance of 90% or more at a wavelength of 400 to 800 nm.

  Examples of the present invention will be specifically described below.

[Examples 1 to 4]
Preparation of oxide vapor deposition material In ₂ O ₃ powder having an average particle diameter of 0.8 μm and SnO ₂ powder having an average particle diameter of 1 μm as raw material powder, these In ₂ O ₃ powder and SnO ₂ powder were They were blended at a ratio such that the Sn / In atomic ratio was 0.048, placed in a resin pot, and mixed by a wet ball mill. At this time, hard ZrO ₂ balls were used, and the mixing time was 20 hours.

  After mixing, the slurry was taken out, and a polyvinyl alcohol binder was added to the resulting slurry, which was dried with a spray dryer or the like and granulated.

Using this granulated product, uniaxial pressure molding was performed at a pressure of 98 MPa (1 ton / cm ² ) to obtain a cylindrical molded body having a diameter of 30 mm and a thickness of 40 mm.

  Next, the obtained molded body was sintered as follows.

That is, after debinding treatment of the molded body by heating for about 10 hours at 300 ° C. in the atmosphere in the sintering furnace, oxygen is supplied at a rate of 5 liters / minute per 0.1 m ^{3 of} the furnace volume. In the atmosphere to be introduced, the temperature was increased at a rate of 1 ° C./min and sintered at 1250 ° C. for 2 hours (atmospheric pressure sintering method). At this time, the temperature was lowered to 1000 ° C. at a rate of 10 ° C./min while introducing oxygen during cooling after sintering.

  Next, the introduced gas is switched to a mixed gas of oxygen and argon, heated and held at 1000 ° C. for 15 hours (hereinafter, this step is referred to as a sintered body oxygen content adjusting step), and then the temperature is lowered to room temperature at 10 ° C./min. did.

And the oxide sintered compact (oxide vapor deposition material) of various L ^* value was able to be obtained by changing the mixing ratio of oxygen of the said mixed gas, and argon.

  That is, the oxide vapor deposition material according to Example 1 is manufactured under the condition that the oxygen gas / argon gas flow rate ratio (that is, the volume ratio) is “40/60”, and the oxide vapor deposition material according to Example 2 has the above volume ratio. Manufactured under the condition of “60/40”, the oxide vapor deposition material according to Example 3 is produced under the condition that the volume ratio is “80/20”, and the oxide vapor deposition material according to Example 4 has the above volume. It is manufactured under the condition of the ratio “90/10”.

When the density was calculated by measuring the volume and weight of the obtained oxide sintered body (oxide vapor deposition material), it was 4.8 to 5.7 g / cm ³ . Moreover, when the average value of 100 crystal grain diameters in an oxide sintered compact was calculated | required from the observation with the scanning electron microscope of the fracture surface of the said oxide sintered compact, all were 3-10 micrometers. Further, the specific resistance was calculated by measuring the surface resistance with respect to the electron beam irradiated surface of the oxide sintered body with a four-end needle method resistivity meter, and it was 1 kΩcm or less. Furthermore, composition analysis was performed on all oxide sintered bodies by ICP emission analysis, and it was found that they had a charged composition. Further, when the L ^* value in the CIE1976 color system was measured for the sintered body surface and the inside of the sintered body using a color difference meter (Spectroguide manufactured by BYK-Gardner GmbH, E-6834), almost the same value was obtained. showed that.

Table 1 shows the oxygen gas / argon gas flow rate ratio (that is, the volume ratio) of the mixed gas introduced in the sintered body oxygen content adjusting step and the L ^* value of the obtained oxide sintered body (oxide vapor deposition material). .

[Preparation of transparent conductive film, evaluation of film characteristics, evaluation of film formation]
(1) A magnetic field deflection type electron beam evaporation apparatus was used for the production of the transparent conductive film.

The evacuation system is composed of a low evacuation system using a rotary pump and a high evacuation system using a cryopump, and can evacuate up to 5 × 10 ⁻⁵ Pa. The electron beam is generated by heating the filament, accelerated by an electric field applied between the cathode and anode, bent in the magnetic field of a permanent magnet, and then irradiated onto an oxide deposition material installed in a tungsten crucible. The The intensity of the electron beam can be adjusted by changing the voltage applied to the filament. Further, the irradiation position of the beam can be changed by changing the acceleration voltage between the cathode and the anode.

  Film formation was performed under the following conditions.

Ar gas and O ₂ gas were introduced into the vacuum chamber to maintain the pressure at 1.5 × 10 ⁻² Pa. At this time, the characteristics of the transparent conductive film obtained by changing the mixing ratio of Ar gas and O ₂ gas introduced into the vacuum chamber were evaluated. A columnar oxide vapor deposition material of Examples 1 to 4 was placed upright on a tungsten crucible, and the central portion of the circular surface of the oxide vapor deposition material was irradiated with an electron beam on a Corning 7059 glass substrate having a thickness of 1.1 mm. A transparent conductive film having a thickness of 200 nm was formed on the substrate. The set voltage of the electron gun was 9 kV, the current value was 150 mA, and the substrate was heated to 250 ° C.

(2) The characteristics of the obtained thin film (transparent conductive film) were evaluated by the following procedure.

First, the surface resistance of the thin film (transparent conductive film) was measured with a four-end needle method resistivity meter Loresta EP (manufactured by Dia Instruments, MCP-T360 type). Using a roughness meter (manufactured by Tencor), evaluation was made based on the difference in level between the non-deposited portion and the deposited portion, and “specific resistance (μΩcm)” was calculated. Furthermore, the “carrier concentration (cm ⁻³ )” and “hole mobility (cm ² / Vs)” of the film at room temperature by the Van der Pauw method were measured using a Hall effect measuring device (ResiTest manufactured by Toyo Corporation). .

Next, the transmittance [T _{L + B} (%)] of the film (glass substrate B with film L) including the glass substrate is measured with a spectrophotometer (manufactured by Hitachi, Ltd., U-4000), and measured by the same method. The transmittance of the film itself was calculated from [T _{L + B} ÷ T _B ] × 100 (%) from the transmittance [(T _B (%)] of the glass substrate alone (glass substrate B).

  The crystallinity of the film was evaluated by X-ray diffraction measurement. As the X-ray diffractometer, X'Pert PROMPD (manufactured by PANalytical) was used, the measurement conditions were wide-area measurement, CuKα rays were used, and measurement was performed at a voltage of 45 kV and a current of 40 mA. The film crystallinity was evaluated from the presence or absence of an X-ray diffraction peak. This result is also shown in the “film crystallinity” column of Table 1.

  Next, the composition of the film (Sn / In atomic ratio) was measured by ICP emission analysis. Further, the adhesion of the film to the substrate was evaluated based on JIS C0021. The evaluation was good (strong) when there was no film peeling, and was insufficient (weak) when there was film peeling. These results are also shown in the columns of “Sn / In atomic ratio” and “Adhesive force of film to substrate” in Table 1.

The specific resistance and transmittance of each thin film (transparent conductive film) depended on the mixing ratio of Ar gas and O ₂ gas introduced into the film forming vacuum chamber during film forming. The mixing ratio of O ₂ gas [O ₂ / (Ar + O ₂ ) (%)] was changed from 0 to 50% in increments of 1%, and the mixing ratio of O ₂ gas showing the lowest specific resistance was determined as the optimum oxygen mixing amount As determined. The results are shown in the “optimum oxygen mixing amount” column of Table 1.

  A thin film (transparent conductive film) produced with an oxygen amount smaller than the optimum oxygen mixing amount was not only poor in conductivity but also low in the visible region. The thin film (transparent conductive film) produced with the optimum oxygen mixing amount not only has good conductivity, but also has high transmittance in the visible region.

(3) Using the oxide vapor deposition materials of Examples 1 to 4, when the above film formation evaluation is performed, the optimum oxygen mixing amount, the specific resistance of the film at that time, in the visible region (wavelength 400 to 800 nm) The average transmittance of the membrane itself was determined.

  These evaluation results are shown in Table 1 “specific resistance (μΩcm)” and “visible transmittance (%)” of the film itself.

  In the film formation using the oxide vapor deposition materials of Examples 1 to 4, the optimum oxygen mixing amount to be introduced into the film formation vacuum chamber in order to obtain the transparent conductive film having the lowest resistance and high permeability was very small. This is because each oxide vapor deposition material contained an optimal amount of oxygen. Further, the film produced at the optimum oxygen mixing amount showed the same composition as the oxide vapor deposition material, and not only showed a very low specific resistance but also a high transmittance in the visible range. Further, it was confirmed that the film was a crystal film of indium oxide having a bixbyite structure, and the adhesion to the substrate was strong, which was practically sufficient.

  Furthermore, the set voltage of the electron gun was 9 kV, and the current value was 150 mA. The oxide vapor deposition material after electron beam irradiation for 60 minutes was observed, and it was visually observed whether the oxide vapor deposition material was cracked or cracked (oxide vapor deposition material durability test). Even if it used continuously for the oxide vapor deposition material of Examples 1-4, a crack did not generate | occur | produce (evaluation of "no crack").

  Such a transparent conductive film can be said to be very useful as a transparent electrode of a solar cell.

[Comparative Examples 1-2]
In Examples 1 to 4, oxide sintered bodies were manufactured by changing only the mixing ratio of the introduced gas in the sintered body oxygen content adjusting step. That is, in Comparative Example 1, the O ₂ / Ar flow rate ratio was 30/70, and in Comparative Example 2, it was 100/0. About the obtained sintered compact, the density, the specific resistance, the crystal grain size, and the composition were evaluated in the same manner, but were equivalent to those of Examples 1 to 4. The obtained oxide sintered body had the same surface color and internal color, and when its L ^* value was measured, it showed the values shown in Table 1.

  Next, as in Examples 1 to 4, film formation evaluation was performed.

  The results are also shown in Table 1 above.

Comparative Example 1 is an oxide vapor deposition material whose L ^* value showed a value (49) smaller than the specified range (54 to 75) of the present invention, and was compared with the oxide vapor deposition materials of Examples 1 to 4. The optimum oxygen mixing amount at the time of filming was large (15). As for the characteristics of the membrane at the optimum oxygen mixing amount, the transmittance was the same as in Examples 1 to 4, but the specific resistance was slightly higher. This is probably because the compositional deviation of the film was large. Furthermore, the film of Comparative Example 1 had weaker adhesion to the substrate than Examples 1-4. This is probably because the film was formed by introducing a large amount of oxygen during film formation. Such an oxide vapor-deposited material has a large compositional deviation in the resulting film, and thus it is difficult to design the film composition. Further, since it is necessary to introduce a large amount of oxygen into the film formation vacuum chamber, when used in the mass production process of film formation, variations in composition and characteristics increase due to the influence of oxygen concentration variation in the vacuum chamber. Therefore, it is confirmed that the oxide vapor deposition material of Comparative Example 1 is not suitable for film formation mass production.

Moreover, the comparative example 2 is an example of the oxide vapor deposition material in which L ^* value showed the value (79) larger than the prescription | regulation range of this invention. The optimum oxygen mixing amount at the time of film formation was 0%, but the specific resistance of the film was higher than those in Examples 1 to 4. This is presumably because the amount of oxygen supplied from the oxide vapor deposition material to the film was too large and the amount of oxygen in the film was large, so that the optimum amount of oxygen deficiency could not be introduced. Therefore, it is confirmed that even if a film is formed using such an oxide vapor deposition material, a film exhibiting high conductivity inherent in the composition of the vapor deposition material cannot be obtained.

[Comparative Example 3]
Next, an indium oxide sintered body containing tin was manufactured in accordance with the sputtering target sintered body manufacturing technique introduced in Japanese Patent Application Laid-Open No. 5-112866 (reference publication).

First, the average particle size of _In 2 _{O 3} powder and the average particle size of less than or equal to 1μm is the following SnO ₂ powder 1μm as a raw material powder, _{an In} 2 O at a rate such as atomic ratio of Sn / an In becomes 0.048 ₃ powders and SnO ₂ powders were mixed, put into a resin pot, and mixed by a wet ball mill. At this time, hard ZrO ₂ balls were used, and the mixing time was 20 hours. After mixing, the slurry was taken out, filtered, dried and granulated.

Then, using the obtained granulated powder, a pressure of 196 MPa ( ² ton / cm ² ) is applied and molding is performed by a cold isostatic press, and the obtained molded body is put in a sintering furnace, Sintered at 1520 ° C. for 5 hours.

The obtained sintered body was processed into a cylindrical shape having a diameter of 30 mm and a thickness of 40 mm. The density of the sintered body was 6.0 g / cm ³ and the specific resistance was 0.6 mΩcm. The crystal grain size was 12 to 15 μm, and the composition was almost the same as the charged composition. The surface and internal color of the obtained sintered body were equivalent, and its L ^* value was measured. As a result, it was very low (38) as shown in Table 1. This indicates that the amount of oxygen in the oxide vapor deposition material is very small.

  Moreover, film-forming evaluation was implemented similarly to Examples 1-4.

  The results are also shown in Table 1 above.

Comparative Example 3 shows a value (38) in which the L ^* value is significantly smaller than the specified range (54 to 75) of the present invention. Compared with the oxide vapor deposition materials of Examples 1 to 4 having the same composition, the optimum oxygen mixing amount at the time of film formation is very large (42). As for the characteristics of the membrane at the optimum oxygen mixing amount, the transmittance was the same as in Examples 1 to 4, but the specific resistance was high. This is probably because the compositional deviation of the film was large. Furthermore, the film of Comparative Example 3 was weaker in adhesion to the substrate than in Examples 1 to 4. This is probably because the film was formed by introducing a large amount of oxygen during film formation. Such an oxide vapor deposition material is difficult to design the film composition because the composition deviation of the obtained film is large. Further, since it is necessary to introduce a large amount of oxygen into the film formation vacuum chamber, when used in the mass production process of film formation, variations in composition and characteristics increase due to the influence of oxygen concentration variation in the vacuum chamber. Moreover, when the oxide vapor deposition material durability test was performed on the same conditions as Examples 1-4, the oxide vapor deposition material after continuous film-forming had a crack (evaluation of "crack"). When film formation is continuously performed using such an oxide vapor deposition material having cracks, problems such as large fluctuations in the film formation speed occur and stable film formation cannot be achieved.

  Therefore, it was confirmed that the oxide vapor deposition material of Comparative Example 3 is not suitable for mass production of films.

[Examples 5 to 8]
Example 1 including the conditions for adjusting the oxygen content of the sintered body, except that when the In ₂ O ₃ powder and the SnO ₂ powder were prepared, the Sn / In atomic ratio was 0.102. The oxide sintered compact (oxide vapor deposition material) of Examples 5-8 was produced on the completely same conditions as -4.

  That is, the oxide vapor deposition material according to Example 5 is manufactured under the condition that the oxygen gas / argon gas flow ratio (that is, the volume ratio) is “40/60”, and the oxide vapor deposition material according to Example 6 has the above volume ratio. Manufactured under the condition of “60/40”, the oxide vapor deposition material according to Example 7 is produced under the condition where the volume ratio is “80/20”, and the oxide vapor deposition material according to Example 8 has the above volume. It is manufactured under the condition of the ratio “90/10”.

And about the obtained oxide sintered compact (oxide vapor deposition material) of Examples 5-8, when density, specific resistance, crystal grain size, and composition were evaluated similarly, all were equivalent to Examples 1-4. Met. Moreover, the surface and internal color of the obtained oxide sintered body were equivalent. The results of measuring the L ^* values are shown in Table 1 above.

  Moreover, film-forming evaluation was implemented similarly to Examples 1-4.

  The results are also shown in Table 1 above.

  In the film formation using the oxide vapor deposition materials of Examples 5 to 8, the optimum oxygen mixing amount to be introduced into the film formation vacuum chamber in order to obtain the transparent conductive film having the lowest resistance and the high permeability is as described in Examples 1 to 8. Like 4 it was very little. This is because the optimum amount of oxygen was contained in the oxide vapor deposition material. Further, the film produced at the optimum oxygen mixing amount showed the same composition as the oxide vapor deposition material, and not only showed a very low specific resistance but also a high transmittance in the visible range. In addition, all the films were indium oxide bixbite crystal structures, and the adhesion of the films to the substrate was strong and practically sufficient. Furthermore, even if the oxide vapor deposition material of Examples 5-8 was used continuously, a crack did not generate | occur | produce.

  Such a transparent conductive film can be said to be very useful as a transparent electrode of a solar cell.

[Comparative Examples 4 to 5]
In Comparative Examples 1 and 2, oxide deposition was performed under the same conditions as in Comparative Examples 1 and 2, except that the atomic ratio of Sn / In in preparing In ₂ O ₃ powder and SnO ₂ powder was set to 0.102. A material was prepared. That is, the conditions for adjusting the amount of oxygen in the sintered body were 30/70 in the O ₂ / Ar flow ratio in Comparative Example 4 and 100/0 in Comparative Example 5. About the obtained sintered compact, although the density, specific resistance, crystal grain size, and composition were evaluated similarly, it was equivalent to Examples 5-8. Further, the surface and the internal color of the obtained sintered body were the same, and when the L ^* value was measured, the values shown in Table 1 were shown.

  Next, as in Examples 1 to 4, film formation evaluation was performed.

  The results are also shown in Table 1.

Comparative Example 4 is an oxide vapor deposition material whose L ^* value showed a value (50) smaller than the specified range (54 to 75) of the present invention, and when the oxide vapor deposition materials of Examples 5 to 8 were used. In comparison, the optimum oxygen mixing amount during film formation was as large as (15). As for the characteristics of the membrane at the optimum oxygen mixing amount, the transmittance was almost the same as in Examples 5 to 8, but the specific resistance was slightly higher. This is presumably because the composition deviation of the film was large and tin was excessively contained in the film. Furthermore, the film of Comparative Example 4 had weaker adhesion to the substrate than Examples 5-8. The reason for such a large compositional deviation and low adhesion is that the film was formed by introducing a large amount of oxygen during film formation. Such an oxide vapor deposition material is difficult to design the film composition because the composition deviation of the obtained film is large. In addition, since it is necessary to introduce a large amount of oxygen into the film formation vacuum chamber, when used in the mass production process of film formation, the composition and characteristics are significantly susceptible to variations due to the influence of oxygen concentration variation in the vacuum chamber. . Therefore, it was confirmed that the oxide vapor deposition material of Comparative Example 4 is also unsuitable for film production.

Moreover, the comparative example 5 is an example of the oxide vapor deposition material in which L ^* value showed the value (82) larger than the prescription | regulation range of this invention. The optimum oxygen mixing amount at the time of film formation was 0%, but the specific resistance of the film was higher than those in Examples 5-8. This is presumably because the oxygen supplied from the oxide deposition material to the film was too much and the amount of oxygen in the film was so large that the optimum amount of oxygen deficiency could not be introduced. Therefore, it is confirmed that even if a film is formed using such an oxide vapor deposition material, a film exhibiting high conductivity inherent in the composition of the oxide vapor deposition material cannot be obtained.

[Comparative Example 6]
In Comparative Example 3, an oxide vapor deposition material was produced under the same conditions as in Comparative Example 3, except that the Sn / In atomic ratio at the time of preparing In ₂ O ₃ powder and SnO ₂ powder was set to 0.102. . The obtained sintered body was similarly evaluated in terms of density, specific resistance, crystal grain size, and composition, and was equivalent to Comparative Example 3. Further, the surface and the internal color of the obtained sintered body were equivalent, and the L ^* value was measured, and the values shown in Table 1 were shown.

  Next, as in Examples 1 to 4, film formation evaluation was performed.

  The results are also shown in Table 1.

Comparative Example 6 also shows a value (49) in which the L ^* value is significantly smaller than the specified range (54 to 75) of the present invention. Compared with the oxide vapor deposition materials of Examples 5 to 8 having the same composition, the optimum oxygen mixing amount at the time of film formation is very large (42). As for the characteristics of the membrane at the optimum oxygen mixing amount, the transmittance was the same as in Examples 5 to 8, but the specific resistance was high. This is probably because the compositional deviation of the film was large. Furthermore, the film of Comparative Example 6 had weaker adhesion to the substrate than Examples 5-8. This is because the film was formed by introducing a large amount of oxygen during film formation. Such an oxide vapor deposition material is difficult to design the film composition because the composition deviation of the obtained film is large. Further, since it is necessary to introduce a large amount of oxygen into the film formation vacuum chamber, when used in the mass production process of film formation, variations in composition and characteristics increase due to the influence of oxygen concentration variation in the vacuum chamber. Moreover, when the oxide vapor deposition material durability test was performed on the same conditions as Examples 1-4, the oxide vapor deposition material after continuous film-forming had a crack (evaluation of "crack"). When film formation is continuously performed using such an oxide vapor deposition material having cracks, problems such as large fluctuations in the film formation speed occur and stable film formation cannot be achieved.

  From the above, it is confirmed that the oxide vapor deposition material of Comparative Example 6 is also unsuitable for film formation mass production.

[Examples 9 to 14]
The blending ratio when blending In ₂ O ₃ powder and SnO ₂ powder is 0.001 (Example 9), 0.009 (Example 10), 0.028 (Example 11) in terms of the Sn / In atomic ratio. ), 0.163 (Example 12), 0.230 (Example 13), and 0.614 (Example 14). The same conditions as in Example 2 (ie, oxygen gas / The oxide sintered bodies (oxide vapor deposition materials) of Examples 9 to 14 were manufactured under the conditions of an argon gas flow rate ratio of “60/40”.

And about the obtained oxide sintered compact (oxide vapor deposition material) of Examples 9-14, when density, specific resistance, crystal grain size, and composition were evaluated similarly, all were equivalent to Example 2. It was. Moreover, the surface and internal color of the obtained oxide sintered body were equivalent. The results of measuring the L ^* values are shown in Table 1 above.

  Moreover, film-forming evaluation was implemented similarly to Examples 1-4.

  The results are also shown in Table 1 above.

  In the film formation using the oxide vapor deposition materials of Examples 9 to 14, the optimum oxygen mixing amount to be introduced into the film formation vacuum chamber in order to obtain the transparent conductive film having the lowest resistance and the high permeability is the values of Examples 1 to Like 4 it was very little. This is because the optimum amount of oxygen was contained in the oxide vapor deposition material. In addition, the film manufactured at the optimum oxygen mixing amount showed the same composition as the oxide vapor deposition material, and not only showed a very low specific resistance, but also showed a high transmittance in the visible region. Further, it was confirmed that all the films were indium oxide bixbite type crystal structures, and the adhesion of the films to the substrate was strong and practically sufficient. Moreover, although the oxide vapor deposition material durability test was done on the conditions similar to Examples 1-4, the oxide vapor deposition material of Examples 9-14 did not generate | occur | produce a crack even if it used continuously.

  Such a transparent conductive film can be said to be very useful as a transparent electrode of a solar cell.

[Comparative Example 7]
Next, an ITO oxide vapor deposition material introduced in JP-A-8-104978 (Patent Document 1) was produced and evaluated in the same manner.

That is, tin oxide powder with an average particle diameter of 1 μm is blended in an indium oxide powder with an average particle diameter of 0.1 μm so that the Sn / In atomic ratio is 0.102, and a 2 mass% vinyl acetate binder is added. did. This was mixed in a wet ball mill for 16 hours, dried and pulverized to obtain a granulated powder. Furthermore, using this granulated powder, a pressure of 49 MPa (500 kgf / cm ² ) was applied by a cold isostatic press to form a cylindrical molded body. This molded body was sintered in the atmosphere. In the sintering process, the temperature was raised from room temperature to 600 ° C. in 10 hours, and the temperature was increased to 1450 ° C. in 4 hours and 40 minutes. And it hold | maintained at 1450 degreeC for 10 hours, and obtained the sintered compact.

The obtained sintered body was processed into a cylindrical shape having a diameter of 30 mm and a thickness of 40 mm to obtain an ITO oxide vapor deposition material. The density of the sintered body was 4.4 g / cm ³ and the specific resistance was 1.2 mΩcm. The crystal grain size was 12-16 μm, and the composition was almost the same as the charged composition. The surface color and the internal color of the sintered body were the same, and when the L ^* value was measured, it was an extremely low value (49) as shown in Table 1. This indicates that the amount of oxygen in the oxide vapor deposition material is very small.

  Moreover, film-forming evaluation was implemented similarly to Examples 1-4.

  The results are also shown in Table 1 above.

In Comparative Example 7, the L ^* value also shows a significantly small value (49) as described above compared with the specified range (54 to 75) of the present invention, and film formation is performed as compared with the oxide vapor deposition materials of Examples 5 to 8. The optimum oxygen mixing amount at that time is very large (42). As for the characteristics of the membrane at the optimum oxygen mixing amount, the transmittance in the visible region was the same as in Examples 5 to 8, but the specific resistance was high. This is probably because the compositional deviation of the film was large. Furthermore, the film of Comparative Example 7 had weaker adhesion to the substrate than Examples 5-8. This is because the film was formed by introducing a large amount of oxygen during film formation. Such an oxide vapor deposition material is difficult to design the film composition because the composition deviation of the obtained film is large. Further, since it is necessary to introduce a large amount of oxygen into the film formation vacuum chamber, when used in the mass production process of film formation, variations in composition and characteristics increase due to the influence of oxygen concentration variation in the vacuum chamber. Moreover, when the oxide vapor deposition material durability test was performed on the same conditions as Examples 1-4, the oxide vapor deposition material after continuous film-forming had a crack (evaluation of "crack"). When film formation is continuously performed using such an oxide vapor deposition material having cracks, problems such as large fluctuations in the film formation speed occur and stable film formation cannot be achieved.

  From the above, it is confirmed that the oxide vapor deposition material of Comparative Example 7 is also unsuitable for film formation mass production.

[Comparative Example 8]
Moreover, the ITO oxide vapor deposition material introduced by Unexamined-Japanese-Patent No. 2007-84881 (patent document 2) was manufactured, and the same evaluation was performed.

That is, tin oxide powder with an average particle size of 1 μm or less is blended in an indium oxide powder with an average particle size of 1 μm or less so that the Sn / In atomic ratio is 0.102, and a 2 mass% vinyl acetate binder is added. did. This was mixed for 18 hours in a wet ball mill using hard ZrO ₂ balls, dried and ground, and then granulated powder. Furthermore, using this granulated powder, a pressure of 94 MPa (3 ton / cm ² ) was applied by a cold isostatic press to obtain a cylindrical shaped body.

The obtained molded body was put into a sintering furnace, an atmosphere was created by introducing oxygen at a rate of 5 liters / minute per 0.1 m ^{3 of} the furnace volume, and atmospheric pressure sintering was performed at 1100 ° C. for 2 hours. At this time, the temperature was raised at 1 ° C./min. During cooling after sintering, the introduction of oxygen was stopped and the temperature was lowered to 1000 ° C. at 10 ° C./min.

  The obtained oxide sintered body was processed into a cylindrical shape with a diameter of 30 mm and a thickness of 40 mm using a vertical machining center, and the volume and weight were measured to calculate the density.

The density of the sintered body was 4.8 g / cm ³ . Further, the surface color and the internal color of the sintered body are the same, and when the L ^* value thereof was measured, as shown in Table 1, a larger value (79) than the specified range (54 to 75) of the present invention was obtained. Indicated. This indicates that the amount of oxygen in the oxide deposition material is very large.

  Film formation evaluation was carried out in the same manner as in Examples 1 to 4 using the oxide vapor deposition material thus prepared.

  The optimum oxygen mixing amount at the time of film formation was 0% as in Comparative Example 2, but the specific resistance of the film was higher than in Examples 5-8. This is presumably because the amount of oxygen supplied from the oxide vapor deposition material to the film was too large and the amount of oxygen in the film was large, so that the optimum amount of oxygen deficiency could not be introduced. Therefore, it is confirmed that even if a film is formed using such an oxide vapor deposition material, a film exhibiting high conductivity inherent in the composition of the vapor deposition material cannot be obtained.

  By applying the oxide vapor deposition material according to the present invention, it becomes possible to produce a transparent conductive film exhibiting high conductivity while exhibiting high light transmittance in the visible range by a vacuum vapor deposition method. It has industrial applicability to be used as an oxide vapor deposition material for forming a transparent electrode.

Claims (4)

In the oxide vapor deposition material used when producing a transparent conductive film by vacuum vapor deposition,
The main component is indium oxide, tin is included, and the oxide sintered body is manufactured by an atmospheric pressure sintering method. The tin content is 0.001 to 0.00 in terms of the Sn / In atomic ratio. The oxide vapor deposition material characterized by being 614 and having an L ^* value of 54 to 75 in the CIE 1976 color system.   2. The oxide vapor deposition material according to claim 1, wherein the tin content is 0.040 to 0.163 in terms of the Sn / In atomic ratio. The oxide sintered body has a furnace internal volume of 0.1 m. ^Three 2. The oxide vapor deposition material according to claim 1, wherein the oxide vapor deposition material is manufactured by an atmospheric pressure sintering method in which oxygen is fired at a temperature of 1150 to 1300 ° C. while introducing oxygen at a rate of 5 liters / minute or more into the furnace. . In the manufacturing method of the oxide vapor deposition material of Claim 1,
Using each powder of indium oxide and tin oxide as raw materials, mixing so that the tin content is 0.001 to 0.614 in the Sn / In atomic ratio, and granulating to obtain a granulated powder, A molded body preparation step for molding the obtained granulated powder;
After performing the binder removal treatment at a temperature of 300 to 500 ° C. to the shaped body while introducing oxygen percentage in volume 0.1 m ³ per 5 liters / minute or more furnace into the furnace, furnace capacity 0.1 m ³ A debinding and baking step of performing a baking treatment at a temperature of 1150 to 1300 ° C. while introducing oxygen at a rate of 5 liters / minute or more into the furnace,
The oxygen and argon mixing ratio (volume ratio) is in the range of O ₂ / Ar = 40/60 to 90/10, and oxygen at a rate of 5 liters / minute or more per 0.1 m ^{3 of} the furnace volume An oxygen amount adjusting step for adjusting the oxygen amount for 10 hours or more at a temperature of 900 to 1100 ° C. with respect to the sintered body while introducing a mixed gas of argon into the furnace;
The manufacturing method of the oxide vapor deposition material characterized by comprising each process of these.