JP2009166324A - Indium oxide film laminate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an indium oxide film laminate low in volume resistivity, improved in surface smoothness by suppressing columnar growth and characterized in that a (400) plane and a (440) plane have strong orientation properties equal to or more than those of a (222) plane. <P>SOLUTION: The indium oxide film laminate is formed by making an indium oxide film 3 overlie a substrate 2, and the indium oxide film 3 is characterized in that the (400) plane and the (440) plane are strongly oriented to a degree equal to or more than the (222) plane. The indium oxide film laminate is manufactured by bringing an indium oxide film forming solution, which contains an indium salt and nitrate ions and also contains diketone or ketoester as a solvent, into contact with the substrate 2 heated to an indium oxide film forming temperature or above to form the indium oxide film 3 on the substrate 2. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an indium oxide film laminate excellent in surface smoothness used as a transparent conductive film and the like, and a method for producing the same.

Conventionally, an ITO transparent conductive film (hereinafter sometimes referred to as an ITO film) composed of indium oxide and a small amount of a tin compound is known to have both excellent light transmittance and conductivity. Taking advantage of these characteristics, it is used in a wide range of fields such as liquid crystal displays, touch panel displays, and dye-sensitized solar cells.
As a method for producing such an ITO film, for example, a surfactant is added to a coating solution in which indium chloride and stannous chloride or stannic chloride are dissolved in water, alcohol, or a water-alcohol mixed solution. And the method of forming an ITO film | membrane by the dip coating method is proposed (refer patent document 1). In this method, an ITO film having a thickness of 15 nm or less can be formed on the substrate by one-time dip coating after being applied to the substrate, and this operation is repeated twice or more to form a multilayer film. As a result, an ITO film having a volume resistivity of the order of 10 ⁻⁴ Ω · cm is manufactured.
Further, a method for producing an ITO transparent conductive film having a volume resistivity of 9.5 × 10 ⁻⁵ Ω · cm, which is lower than that of the above method, has been proposed (see Non-Patent Document 1). In this method, indium (III) chloride and tin (II) chloride are dissolved in ethanol, and this raw material solution is sprayed onto a heated substrate to produce a columnar ITO film (spray pyrolysis method).
In any of the ITO films, since the cubic plane index (222) plane derived from the indium oxide film appears very strongly, an ITO film having a large grain boundary was obtained. In particular, although the film obtained by the spray pyrolysis method has high performance, the crystal grows in a columnar shape, so when a new layer is further laminated thereon, the surface smoothness is poor, and surface polishing or the like is performed in advance. There was a problem that had to be done.

JP 2002-175733 A New Development of Transparent Conductive Film II (Publisher: CMC Publishing Co., Ltd.) Published October 2002, pages 113-121

  The present invention provides an indium oxide film laminate in which the (400) plane and the (440) plane have the same or higher strong orientation as the (222) plane, the volume resistivity is low, and the surface smoothness is improved. The purpose is to provide.

The present invention has been completed as a result of intensive research and development to solve the above-mentioned problems, and is an invention having the following contents.
1. An indium oxide film laminate produced on a substrate, wherein the (400) plane and the (440) plane are strongly oriented to be equal to or greater than the (222) plane.
2. 2. The indium oxide film laminate according to 1 above, wherein the indium oxide film further contains a doping metal source.
3. 3. The indium oxide film laminate according to 1 or 2, wherein the substrate is a porous substrate or a substrate provided with a porous film.
4). A method for producing an indium oxide film laminate, wherein an indium oxide film-forming solution containing an indium salt is brought into contact with a substrate heated to an indium oxide film formation temperature or higher to produce an indium oxide film on the substrate, A method for producing an indium oxide film laminate, wherein the indium oxide film forming solution contains nitrate ions and contains a diketone or ketoester solvent.
5. 5. The method for producing an indium oxide film laminate according to the above 4, wherein the indium salt is indium nitrate.

  The present invention uses columnar growth by using an indium oxide film made of an indium oxide crystal in which (400) plane and (440) plane both in the plane index of cubic indium oxide are strongly oriented to be equal to or higher than (222) plane. By suppressing as much as possible, it is possible to provide an indium oxide film laminate having a low volume resistivity, excellent surface smoothness, and few grain boundaries. As a result, since the surface is smooth, the desired coating amount can be accurately controlled when a functional layer is further laminated on the laminate.

The present invention relates to an indium oxide film laminate formed on a substrate, wherein the (400) plane and the (440) plane are strongly orientated at least as strong as the (222) plane in the plane index of cubic indium oxide. This is an indium film laminate.
Such an indium oxide film in which the (400) plane and the (440) plane are strongly oriented to be equal to or greater than the (222) plane is obtained by allowing an indium salt and nitrate ions to coexist in the solution for forming an indium oxide film. Can be manufactured.
The indium salt used in the present invention is not particularly limited as long as it is usually an inorganic salt or an organic compound and can form an indium oxide film. Specifically, indium chloride and indium nitrate are used. , Tris (acetylacetonato) indium (III) and the like are preferable examples. In the present invention,
Two or more indium compounds may be used in combination.
Next, the nitrate ion used in the present invention is not particularly limited as long as the (400) plane and the (440) plane can be oriented to the same level or higher as the (222) plane, but nitric acid is added. It is preferable. If indium nitrate is used as the indium salt, indium and nitric acid are added at the same time, which is preferable. In this case, it is not necessary to add more nitric acid, but nitric acid may be further added if necessary. .

In the present invention, when a doping metal source is further added to the indium oxide film for the purpose of doping the indium oxide film, a functional indium oxide film such as an ITO film can be obtained.
The doping metal source may be appropriately selected according to the type of the target indium oxide film. For example, when obtaining an ITO film, a tin element is used as the doping metal source in addition to the indium element. Specific examples of the metal source having such a tin element include tin (II) chloride (SnCl ₂ ), tin (IV) chloride (SnCl ₄ ),
Examples thereof include dialkyltin compounds such as dimethyltin oxide, methylbutyltin oxide, dibutyltin oxide and dioctyltin oxide, and dialkyltin such as dibutyltin diacetate and dibutyltin dilaurate.

As described above, when the indium oxide film laminate is manufactured, it is necessary to heat the substrate to a certain temperature or higher as described above, so that the substrate is particularly limited as long as the substrate has heat resistance against the heating temperature. is not. For example, glass, silicon wafer, SUS, metal plate, ceramic substrate, heat-resistant plastic, etc. can be mentioned, among which glass, silicon wafer, SUS, metal plate, ceramic substrate are versatile and have sufficient heat resistance. Therefore, it is preferable.
The substrate used in the present invention is, for example, one having a smooth surface, one having a fine structure, one having a hole, one having a groove, one having a porous structure, or one having a porous film. It may be provided. Among these, a material having a smooth surface, a material having a fine structure, a material having grooves, a material having a porous structure, or a material having a porous film are preferably used.
In the above, examples of the porous film include those obtained by firing fine metal particles such as titanium oxide.
When the substrate is a porous substrate or a substrate having a porous film, indium oxide crystals usually grow easily from a specific point on the porous surface, and the interface between the substrate and the indium oxide film. In the present invention, even in such a case, the indium element and nitric acid dissolved in the indium oxide film forming solution are generated. By using ions, the (400) plane and the (440) plane of the indium oxide crystal can be made to have a strong orientation equivalent to or higher than the (222) plane. As a result, the surface has a low volume resistivity and the surface. Since an indium oxide film excellent in smoothness, adhesion and transparency and suppressing generation of grain boundaries is obtained, it is preferable.
In the present invention, the indium oxide film laminate is obtained by bringing the indium oxide film-forming solution containing the indium salt and nitrate ions into contact with the substrate a plurality of times.

  Since the indium oxide film laminate provided by the present invention is an indium oxide film laminate excellent in surface smoothness, when a functional layer is further laminated on the laminate, the desired coating amount is accurately set. Can be controlled.

Next, the manufacturing method of the indium oxide film laminated body of this invention is demonstrated.
In the method for producing an indium oxide film laminate according to the present invention, an indium oxide film forming solution in which an indium salt and nitrate ions coexist is brought into contact with a substrate heated to a temperature equal to or higher than an indium oxide film forming temperature. An indium oxide film is formed on the substrate. By performing this contact a plurality of times, a laminate is obtained.
The indium oxide film forming solution used in the present invention needs to contain an indium salt and nitrate ions.
As the indium salt, as described in paragraph 0006, an inorganic salt or an organic compound is used.
The concentration of the indium salt in the solution for forming an indium oxide film is not particularly limited. For example, the concentration is in the range of 0.001 to 1 mol / L, particularly in the range of 0.01 to 0.5 mol / L. It is preferable that If the indium salt concentration is within the above range, the indium oxide film can be formed in a relatively short time.

On the other hand, the concentration of nitrate ions contained in the solution for forming an indium oxide film used in the present invention is not particularly limited. For example, the concentration is 0.01 mol / L or more, and particularly within the range of 0.05 to 1 mol / L. In particular, it is preferably in the range of 0.1 to 0.5 mol / L.
If this concentration is 0.001 mol / L or less, it takes time to form a film. Conversely, if it exceeds 1 mol / L, the thermal decomposition reaction may not be in time, and the film may be roughened.
As described above, indium nitrate is preferably used because indium and nitric acid are added simultaneously. In this case, if the concentration is insufficient in either case, it is sufficient to add only the insufficient component.
The nitrate ion in the present invention suppresses the selective growth of the (222) plane of the indium oxide crystal, and causes the (400) plane and (444) plane orientation to appear strongly. The reason why the orientation of the (222) plane is suppressed and the orientation of the (400) plane and the (440) plane appears in strength is not necessarily clear, but the indium element is surrounded by nitrate ions. It is estimated that the decomposition reaction occurs at a low temperature and grows evenly in all directions.

  Examples of the solvent for the indium oxide film forming solution used in the present invention include diketones such as acetylacetone, diacetyl, and benzoylacetone; ketoesters such as ethyl acetoacetate, ethyl pyruvate, ethyl benzoylacetate, and ethyl benzoylformate; A mixed solvent etc. can be mentioned. By using these solvents, the intended film can be obtained. Of course, other solvents that can dissolve indium salts and the like, for example, water; lower alcohols having a total carbon number of 5 or less, such as methanol, ethanol, isopropyl alcohol, propanol, butanol, etc. ; Toluene or the like may be mixed. The concentration of the diketone or ketoester in the solvent is preferably equal to or higher than the number of moles of metal ions in the indium oxide film forming solution.

In the present invention, as described above, when the doping metal source for doping the indium oxide film is added, the concentration of the doping metal source in the solution for forming the indium oxide film is not particularly limited. For example, it is preferably in the range of 0.001 to 0.5 mol / L, and more preferably in the range of 0.01 to 0.1 mol / L.
If this concentration is less than 0.001 mol / L, the doping effect may be deteriorated. Conversely, if it exceeds 0.5 mol / L, an oxide is formed by itself and the intended purpose is achieved. The possibility not to come out.

In the present invention, the indium oxide film forming solution is brought into contact with a substrate heated to a temperature equal to or higher than the indium oxide film forming temperature. Here, the indium oxide film forming temperature means that the indium element is combined with oxygen. The temperature at which the indium oxide film can be formed on the substrate. This temperature varies greatly depending on the type of indium element source such as an indium inorganic salt or an organic compound, and the composition of an indium oxide film forming solution such as a solvent.
In the present invention, such an indium oxide film formation temperature can be measured by the following method.
That is, an indium oxide film can be formed by preparing a solution for forming an indium oxide film that actually contains a desired indium salt, changing the heating temperature of the substrate, and bringing the solution into contact with the substrate. Measure the lowest substrate heating temperature. This lowest substrate heating temperature can be defined as the indium oxide film forming temperature in the present invention. At this time, whether or not an indium oxide film is formed can be determined from a result obtained from an X-ray diffraction apparatus (for example, RINT-1500, manufactured by Rigaku Corporation).
As described above, the indium oxide film formation temperature varies depending on the type of indium salt or solvent used, but is usually in the range of 200 to 600 ° C. In the present invention, the heating temperature of the substrate is not particularly limited as long as it is a temperature equal to or higher than the indium oxide film formation temperature. For example, the indium oxide film formation temperature + 300 ° C. or less, especially the indium oxide film formation temperature +200. It is preferable that the temperature is not higher than ° C., particularly the indium oxide film forming temperature + 100 ° C. or lower. As mentioned above, the heating temperature of a board | substrate is in the range of 300-600 degreeC normally.

Next, as a method for contacting the substrate and the indium oxide film forming solution in the present invention, as long as the above-described indium oxide film forming solution and the above substrate can be efficiently contacted, particularly, Although not limited, it is preferable that the method does not lower the temperature of the substrate when the indium oxide film forming solution and the substrate are brought into contact with each other. When the temperature of the substrate is lowered, a film formation reaction does not occur, and a desired indium oxide film may not be obtained.
As a method for preventing the temperature of the substrate from being lowered, for example, a method of bringing the indium oxide film forming solution into contact with the substrate as droplets can be mentioned. In the case of this method, it is preferable that the diameter of the droplet is smaller. If the diameter of the droplet is small, the solvent of the solution for forming the indium oxide film can be instantly evaporated, and the decrease in the substrate temperature can be effectively suppressed. Further, the small diameter of the droplet enables uniform indium oxide. A membrane can be obtained.
The method of bringing the droplets of the indium oxide film forming solution having a small diameter into contact with the substrate is not particularly limited. Specifically, the indium oxide film forming solution is sprayed on the substrate. Examples thereof include a contact method and a method in which a substrate is passed through a space in which a solution for forming an indium oxide film is made into a mist.
Examples of the method of bringing the substrate into contact with the substrate by spraying the indium oxide film forming solution described above include, for example, a method of continuously moving and spraying the substrate with a heatable roller, a method of spraying on a fixed substrate, The method of spraying on a pipe-shaped flow path etc. are mentioned.
As a method for continuously moving and spraying the substrate with the roller, for example, the substrate is continuously moved using a roller heated to a temperature equal to or higher than the indium oxide film forming temperature, and the spray device is used to indium oxide. Examples thereof include a method of spraying a film forming solution to form an indium oxide film. This method is preferable because it has an advantage that an indium oxide film can be continuously formed.
Further, as a method of spraying on the fixed substrate, for example, the substrate is heated to a temperature equal to or higher than the indium oxide film forming temperature, and the indium oxide film forming solution is sprayed onto the substrate using a spray device. By doing so, a method of forming an indium oxide film can be exemplified.
Furthermore, as a method of passing the substrate through the space in which the above-mentioned solution for forming an indium oxide film is made mist, for example, in the space in which the solution for forming an indium oxide film is made into a mist, Examples thereof include a method of forming an indium oxide film by passing a substrate heated to a temperature.

  Examples of the method of bringing the indium oxide film forming solution into contact with the substrate by spraying include a spraying method using a spray device or the like. When spraying using the said spray apparatus etc., it is preferable that the diameter of a droplet is in the range of 0.01-1000 micrometers normally, especially in the range of 0.1-300 micrometers. If the diameter of the droplet is within the above range, a significant decrease in the substrate temperature can be suppressed, and a uniform indium oxide film can be obtained.

  The spray gas of the spray device is not particularly limited as long as it does not inhibit the formation of the indium oxide film, and examples thereof include air, nitrogen, argon, helium, and oxygen. Among these, inert gases such as nitrogen, argon, and helium are preferable because they do not affect the indium oxide film. Further, the injection amount of the injection gas is, for example, preferably in the range of 0.1 to 50 L / min, and more preferably in the range of 1 to 20 L / min. Further, the spray device may be a fixed type, a movable type, a rotary type, or a type that sprays only the solution by pressure. As such a spray device, a commonly used spray device can be used, for example, hand spray (spray gun No. 8012, manufactured by ASONE), ultrasonic nepriser (NE-U17, manufactured by OMRON), etc. It can be illustrated.

  In the method of passing the substrate through the mist-like space of the solution for forming an indium oxide film according to the present invention, the diameter of the droplet is usually within a range of 0.01 to 300 μm, and more preferably within a range of 0.1 to 100 μm. It is preferable to be within. If the diameter of the droplet is within the above range, a significant decrease in the substrate temperature can be suppressed, and a uniform indium oxide film can be obtained.

  The method for heating the substrate is not particularly limited, and examples thereof include a heating method such as a hot plate, an oven, a baking furnace, an infrared lamp, a hot air blower, etc. Among them, the substrate temperature is maintained at the above temperature. However, a method capable of contacting the solution for forming the indium oxide film is preferable, and specifically, a hot plate or the like is preferably used.

The contact time between the indium oxide film forming solution and the substrate in the present invention depends on the contact means such as the concentration of indium element in the indium oxide film forming solution, the desired thickness of the laminate, and the type of spray used. Although it can be determined appropriately, it is usually about 1 to 60 minutes.
It is preferable to continuously spray using the spraying means because a continuously thick laminate can be easily manufactured.

The indium oxide film forming solution used in the present invention may further contain additives such as ceramic fine particles and a surfactant in addition to the above essential components.
By using ceramic fine particles, an indium oxide film is formed so as to surround the ceramic fine particles, and a mixed film of different ceramics can be obtained. In addition, the volume of the indium oxide film can be increased. What is necessary is just to select suitably the addition amount of the said ceramic fine particle according to the use etc. of the laminated body to be used.
Examples of the ceramic fine particles include ITO, aluminum oxide, zirconium oxide, silicon oxide, titanium oxide, tin oxide, cerium oxide, calcium oxide, manganese oxide, magnesium oxide, and barium titanate. Etc.
On the other hand, the surfactant acts on the interface between the indium oxide film forming solution and the substrate surface. By using such a surfactant, the wettability of the substrate is improved, the contact area between the solution for forming the indium oxide film and the substrate surface can be improved, and a uniform indium oxide film can be obtained. it can.
In particular, when the indium oxide film forming solution is brought into contact by spraying, the droplets of the indium oxide film forming solution can be sufficiently brought into contact with the substrate surface due to the effect of the above-mentioned surfactant, so that it is preferably used. The
Examples of the surfactant include nonionic surfactants, anionic surfactants, cationic surfactants, and amphoteric surfactants, and are used as appropriate according to the type of solution. can do.
Among these, nonionic surfactants include polyoxyalkylene glycol alkyl ether, fatty acid alkanolamide, polyoxyalkylene glycol, aliphatic alcohol alkylene oxide adduct, polyoxyalkylene glycol alkyl phenyl ether, alkyl monoglyceryl ether, polyoxy Examples include alkylene sorbitan fatty acid esters.
Examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, sulfosuccinates, monoalkyl phosphates, polyoxyalkylene glycol alkyl ether phosphates, and the like.
Examples of the cationic surfactant include alkyl trimethyl ammonium salt, dialkyl dimethyl ammonium salt, alkyl dimethyl benzyl ammonium salt, and the like.
Furthermore, examples of amphoteric surfactants include alkyl betaine type surfactants, alkyl amide betaine type surfactants, and amine oxide type surfactants.
These surfactants include, for example, Surfinol 485, Surfinol SE, Surfinol SE-F, Surfinol 504, Surfinol GA, Surfinol 104A, Surfinol 104BC, Surfinol 104PPM, Surfinol 104E, Surfinol 104PA. Such as Surfynol series (all manufactured by Nissin Chemical Industry Co., Ltd.), NIKKOL AM301, NIKKOL AM313ON (all manufactured by Nikko Chemical Co., Ltd.), etc., and these can be used. In addition, it is preferable to select and use the usage-amount of the said surfactant suitably according to the indium salt etc. to be used.

  Moreover, in the manufacturing method of the indium oxide film laminated body which concerns on this invention, you may wash | clean the indium oxide film obtained by the contact method mentioned above. The cleaning of the indium oxide film is performed to remove impurities present on the surface of the film, and examples include a method of cleaning using a solvent used in the solution for forming the indium oxide film. Can do. Cleaning may be performed by spraying or by dipping in a cleaning solution.

Next, an example of an apparatus for manufacturing an indium oxide film laminate according to the present invention will be described with reference to FIG.
As shown in FIG. 1, the manufacturing apparatus 1 has a substrate 2 placed in a hermetically sealed container, and a spray 7 for spraying a support portion 7 containing a heater 6 and an indium oxide film forming solution 5 toward the substrate 2. Device 4.
In this manufacturing apparatus, the substrate 2 is heated by the heater 6 to a temperature equal to or higher than the indium oxide film formation temperature, and then the indium oxide film forming solution 5 containing indium nitrate is directed toward the substrate 2 using the spray device 4. The conductive film 3 made of an indium oxide film is formed on the substrate 2 by spraying for a certain time. The heater is provided with a temperature control means so that the temperature equal to or higher than the indium oxide film formation temperature can be maintained, and the spraying device also has a control means that makes the operating time and the spray amount as desired. Is provided. For this reason, an indium oxide film and other functional films can be further laminated on the surface of the indium oxide film by intermittently operating the spray device.

  The present invention will be further described with reference to the following examples. However, the present invention is not limited to the following examples.

Example 1
An ITO film was prepared using an indium oxide film forming solution containing indium nitrate.
First, a silicon wafer and fine particle titanium oxide were prepared as substrates. A homogenizer was used so that TiO ₂ fine particles having a primary particle diameter of 20 nm (Nippon Aerosil Co., Ltd., P25) 37.5% by mass, acetylacetone 1.25% by mass, polyethylene glycol (weight average molecular weight 3000) 1.88% by mass were obtained. Then, it was dissolved and dispersed in water and isopropyl alcohol (1: 1 mixed solvent) to prepare a slurry. The slurry was applied onto the silicon wafer with a doctor blade, allowed to stand at room temperature for 20 minutes, and then dried at 100 ° C. for 30 minutes. Thereafter, using an electric muffle furnace (P90, manufactured by Denken), firing was performed at 500 ° C. for 30 minutes in an atmospheric pressure atmosphere. Thus, a substrate having a titanium oxide porous film formed on a silicon wafer was obtained.
Next, indium nitrate (manufactured by Kanto Chemical Co., Inc.) and tin chloride (manufactured by Kanto Chemical Co., Ltd.) and a mixed solvent in which methanol was 40% by mass and ethyl acetoacetate was 60% by mass were prepared. In this mixed solvent, indium nitrate was dissolved at 0.1 mol / L and tin chloride at 0.005 mol / L to obtain 100 mL of an indium oxide film forming solution. Since it was previously known that the indium oxide film forming temperature produced from this indium oxide film forming solution was 300 ° C., the substrate was heated to 400 ° C. with a hot plate (manufactured by ASONE), The indium oxide film forming solution was sprayed on the titanium oxide surface and the silicon wafer surface of this substrate by 100 mL with an ultrasonic nebulizer (manufactured by OMRON Corporation) to obtain an indium oxide film on the substrate.
When the indium oxide film obtained on the silicon wafer substrate by the above method was measured using an X-ray diffraction apparatus (Rigaku, RINT-1500), as shown in FIG. 2, the (400) plane (35.5) was measured. It can be seen that an ITO film having a higher orientation strength in the (°) and (440) planes (51.0 °) than in the (222) plane (30.6 °) is obtained.
When the volume resistivity of the ITO film was measured by a four-terminal method using “Loresta GP” manufactured by Dia Instruments, it was 9.4 × 10 ⁻⁵ Ω · cm. Further, when the average surface roughness was measured by Nanopics 1000 (manufactured by Seiko Instruments Inc.), Ra = 6.7 nm.
Further, the results of observation of the substrate provided with the fine particle titanium oxide layer and the indium oxide film produced on the silicon wafer substrate with a scanning electron microscope (product name: S4500, manufactured by Hitachi, Ltd.) are shown in FIG. ) And FIG. 4 (substrate is titanium oxide) (both magnifications are 50,000 times).
As described above, the laminate obtained by the present invention is an ITO having a very good surface smoothness and few grain boundaries, whether it is a flat substrate such as a wafer or a porous substrate such as titanium oxide. It turns out that it is a film | membrane.

Example 2
In Example 1 above, an ITO film was prepared in the same manner as in Example 1 except that acetylacetone was used instead of ethyl acetoacetate as the solvent. As a result, the same results as in Example 1 were obtained.

Comparative Example 1
In the above Example 1, indium oxide film lamination was performed in the same manner as in Example 1 except that indium chloride (manufactured by Kanto Chemical Co., Inc.) was used instead of indium nitrate and the solvent was methanol (no addition of nitrate ions). Got the body.
FIG. 5 shows the results of measuring the indium oxide film obtained on the silicon wafer substrate in the same manner as described above using an X-ray diffraction apparatus (RINT-1500, manufactured by Rigaku). From FIG. 5, it can be seen that an ITO film exhibiting strong orientation on the (222) plane (30.6 °) is obtained.
When the volume resistivity of the ITO film was measured by a four-terminal method using “Loresta GP” manufactured by Dia Instruments, it was 9.8 × 10 ⁻⁵ Ω · cm. Further, when the average surface roughness was measured with Nanopics 1000 (manufactured by Seiko Instruments Inc.), Ra = 61 nm.
Further, the results of observation of the substrate provided with the fine particle titanium oxide layer and the indium oxide film produced on the silicon wafer substrate with a scanning electron microscope (product name: S4500, manufactured by Hitachi, Ltd.) are shown in FIG. ) And FIG. 7 (the substrate is a silicon wafer).
From the above, when nitrate ions are not present, even in the case of a flat substrate such as a wafer or a porous substrate such as titanium oxide, in any case, it is columnar and has poor surface smoothness. It can also be seen that this is an ITO film with prominent grain boundaries.

  The present invention is a low resistivity indium oxide film laminate excellent in surface smoothness and can be used as a transparent conductive film. Further, by adding a doping metal source, for example, tin can be added to form an ITO film or the like. These transparent conductive films can be used in a wide range of fields such as liquid crystal displays, touch panel displays, and dye-sensitized solar cells.

It is a figure which shows an example of the manufacturing apparatus of the indium oxide film laminated body of this invention. 2 is an X-ray diffraction pattern of the indium oxide film laminate obtained in Example 1. FIG. 1 is a scanning electron micrograph of an indium oxide film laminate on a silicon wafer substrate obtained in Example 1. FIG. 1 is a scanning electron micrograph of an indium oxide film laminate on a titanium oxide substrate obtained in Example 1. FIG. 4 is an X-ray diffraction pattern of the indium oxide film laminate obtained in Comparative Example 1. FIG. 2 is a scanning electron micrograph of an indium oxide film laminate on a titanium oxide substrate obtained in Comparative Example 1. FIG. 6 is a scanning electron micrograph of an indium oxide film stack on a silicon wafer substrate obtained in Comparative Example 1. FIG.

Explanation of symbols

1: Manufacturing apparatus 2: Substrate 3: Conductive film 4: Spray apparatus 5: Metal oxide forming solution 6: Heater 7: Supporting part

Claims (5)

  An indium oxide film laminate produced on a substrate, wherein the (400) plane and the (440) plane are strongly oriented to be equal to or greater than the (222) plane.   The indium oxide film laminate according to claim 1, wherein the indium oxide film further contains a doping metal source.   The indium oxide film laminate according to claim 1, wherein the substrate is a porous substrate or a substrate provided with a porous film.   A method for producing an indium oxide film laminate, wherein an indium oxide film-forming solution containing an indium salt is brought into contact with a substrate heated to an indium oxide film formation temperature or higher to produce an indium oxide film on the substrate, A method for producing an indium oxide film laminate, wherein the solution for forming an indium oxide film contains nitrate ions and contains a diketone or ketoester solvent.   The method for producing an indium oxide film laminate according to claim 4, wherein the indium salt is indium nitrate.

Images