JP4687374B2 - Transparent conductive film and transparent conductive substrate containing the same - Google Patents

Description

  The present invention relates to a transparent conductive film mainly composed of gallium, indium, and oxygen and a transparent conductive substrate including the same. In particular, the present invention relates to a transparent conductive film formed using a sputtering target having a low content of an indium oxide phase and having a high transmittance in a short wavelength region and a transparent conductive substrate including the transparent conductive film.

Oxide transparent conductive films are used as transparent electrodes in various devices because they are excellent in conductivity and light transmittance in the visible range. Practical materials include tin oxide (SnO ₂ ) containing antimony and fluorine as dopants, zinc oxide (ZnO) containing aluminum and gallium as dopants, and indium oxide (In ₂ O ₃ ) containing Sn as dopants. Are known. Among them, indium oxide film containing Sn as a dopant is called ITO (I ndium- T in- O xide ) film, since the transparent conductive oxide film having low resistance can be easily obtained, it is widely utilized Yes.

As a method for forming a transparent conductive film, a sputtering method, a vapor deposition method, an ion plating method, and a solution coating method are often used. Among them, the sputtering method is effective when a material having a low vapor pressure is used or when precise film thickness control is required.
In the sputtering method, generally, argon gas is used, and a voltage is applied under a gas pressure of about 10 Pa or less, using the substrate as an anode and a sputtering target as a raw material for the oxide transparent conductive film to be formed as a cathode. A glow discharge occurs between the electrodes to which a voltage is applied to generate argon plasma, and argon cations in the plasma collide with the cathode sputtering target. Particles that are flipped one after another by this collision are sequentially deposited on the substrate to form a thin film.
Sputtering methods are classified according to the method of generating argon plasma, those using high-frequency plasma are called high-frequency sputtering methods, and those using DC plasma are called DC sputtering methods. In particular, the direct current sputtering method is an optimal film formation method because it has features such as less thermal damage to the substrate, high-speed film formation, inexpensive power supply facilities, and simple operation.

In general, a direct current sputtering method is used to form the ITO film. An ITO film formed at room temperature exhibits a low specific resistance of about 5 × 10 ⁻⁴ Ω · cm. The ITO film has good light transmittance in the visible region, and exhibits an average light transmittance of 80% or more. It also has excellent chemical and thermal stability.

By the way, in recent years, a light emitting material or a light emitting device (for example, LED, laser, organic or inorganic EL) having a function of blue light emission or near ultraviolet light emission (for example, wavelength 300 to 400 nm) (for near ultraviolet LED, Non-Patent Document 1 and Non-Patent Document 2) has become widespread and has been actively developed. A transparent electrode is indispensable for these electronic devices.
JP 7-182924 A Japanese Patent Laid-Open No. 9-259640 JP 2002-093243 A Applied Physics, Vol. 68 (1999), No. 2, pp. 152-155 SEI Technical Review, September 2004 (No. 165), pp. 75-78

In light emitting devices that have focused on visible light having a wavelength of 400 to 800 nm so far, ITO films, ZnO-based and SnO ₂ -based transparent conductive films have been used as transparent electrodes. Although these conventional transparent conductive films have excellent average transmittance in the visible range of wavelengths of 400 to 800 nm, absorption occurs for blue light having a wavelength of about 400 nm and near-ultraviolet light having a shorter wavelength. , Can not penetrate sufficiently.

  Also, touch panels and electronic paper tend to place importance on visibility. Especially for touch panels, a transparent conductive film with a high surface resistance of several hundred Ω / □ or more is more convenient. Therefore, the surface resistance of conventional ITO films is increased and used with insufficient blue light transmittance. I was in a situation where I had to.

The following proposal has been made as a transparent conductive film applied to such a device.
Patent Document 1 proposes gallium indium oxide (GaInO ₃ ) doped with a small amount of a heterovalent dopant such as a tetravalent atom. This oxide crystal film is excellent in transparency and has a refractive index as low as about 1.6. Therefore, the refractive index matching with the glass substrate is improved, and it is about the same as the wide bandgap semiconductor currently used. It is described that the electrical conductivity of can be realized. However, since the crystal film described in Patent Document 1 requires high-temperature film formation at a substrate temperature of 250 to 500 ° C., it is difficult to use it industrially as it is.

Patent Document 2 discloses that the composition range is considerably different from that of conventionally known GaInO _3, which is higher in conductivity than GaInO ₃ and In ₂ O ₃ , that is, a lower resistivity and a transparent having excellent optical characteristics. As a conductive film, a transparent conductive film containing 15 to 49 atomic% of Ga represented by Ga / (Ga + In) in a pseudo binary system represented by Ga ₂ O ₃ —In ₂ O ₃ has been proposed. In particular, it is described that the optical refractive index of this transparent conductive film has a feature that it can be changed from about 1.8 to 2.1 by changing the composition.
However, since the transparent conductive film proposed in Patent Document 2 has a low atomic ratio of gallium to indium, the transmittance at a wavelength of 400 nm or less necessary for the device is not sufficiently high. In the example of Patent Document 2, only data relating to the crystal film is described.

Patent Document 3 discloses an ultraviolet transparent conductive film made of Ga ₂ O ₃ crystal, transparent in a wavelength range of 240 nm to 800 nm or wavelength range of 240 nm to 400 nm, and having electrical conductivity due to oxygen defects or dopant elements. Is proposed, and at least one element of Sn, Ge, Si, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W is used as a dopant, the substrate temperature is 600 ° C. to 1500 ° C., and the oxygen partial pressure is 0. It is described that it is manufactured using any one of a pulse laser deposition method, a sputtering method, a CVD method, and an MBE method as ˜1 Pa.
The Ga ₂ O ₃ crystal film described in Patent Document 3 needs to be formed at a substrate temperature of 600 ° C. to 1500 ° C. in order to obtain conductivity. Since this temperature range is too high, industrial utilization is extremely difficult.

  The present invention has been made in view of the problems as described above, and an object of the present invention is to provide a transparent conductive film having a high light transmittance at a wavelength of 400 nm or less, and a transparent conductive substrate containing the same. There is to do.

In order to achieve the above object, the transparent conductive film according to the present invention is mainly composed of gallium, indium, and oxygen, and the atomic ratio of gallium to indium is 0.97 or more and less than 1.86, and is mainly β-Ga ₂ O. consists gallium oxide, indium phase of ₃ structure (beta-GaInO _3-phase) and indium oxide phase bixbite type structure (an in ₂ O ₃ phase), and, X-rays diffraction peak intensity as defined in equation (1) An oxide film obtained by a direct current sputtering method using an oxide sintered body having a ratio of 45% or less and a density of 5.8 g / cm ³ or more as a sputtering target, mainly composed of gallium, indium, and oxygen, An amorphous film in which the atomic ratio of gallium to indium is 0.97 or more and less than 1.86, and the transmittance of the film itself excluding the substrate is 50%. To the shortest wavelength it is characterized in that at 350nm or less.
In ₂ O ₃ phase (400) / β-GaInO ₃ phase (111) × 100 [%] (1)

  In the transparent conductive film according to the present invention, the atomic ratio of gallium to indium of the sputtering target is 1.14 or more and less than 1.86, and the X-ray diffraction peak intensity ratio defined by the above formula (1) is 40. %, And the shortest wavelength at which the transmittance of the film itself excluding the substrate exhibits 50% is 340 nm or less.

The transparent conductive film according to the present invention preferably has a specific resistance value of 1.0 × 10 ^{−2 to} 5.0 × 10 ⁻¹ Ω · cm.

  The transparent conductive film according to the present invention preferably has an arithmetic average height (Ra) of 1.0 nm or less.

  The transparent conductive substrate according to the present invention includes a glass plate, a quartz plate, a resin plate or a resin film whose one or both sides are covered with a gas barrier film, or a resin plate or a resin film in which a gas barrier film is inserted. One of the transparent conductive films is formed on one side or both sides of a selected transparent substrate.

  In the transparent conductive substrate according to the present invention, preferably, the gas barrier film is a silicon oxide film, a silicon oxynitride (SiON) film, a magnesium aluminate film, a tin oxide-based film, or a diamond-like carbon (DLC) film. It is at least one kind selected from the inside.

  In the transparent conductive substrate according to the present invention, preferably, the material of the resin plate or resin film is polyethylene terephthalate (PET), polyethersulfone (PES), polyarylate (PAR), polycarbonate (PC), polyethylene. Naphthalate (PEN) or a layered structure in which the surface of these materials is covered with an acrylic organic material is characterized.

According to the present invention, it is possible to obtain an amorphous transparent conductive film that transmits blue light or near ultraviolet light having a wavelength of 400 nm or less, which has not been obtained conventionally. Such a transparent conductive film, when used as an electrode of a blue or near-ultraviolet LED or laser, or a device utilizing organic or inorganic EL, has a high light transmittance in the visible light short wavelength region or near ultraviolet region. Since it can be obtained, it is industrially useful. In addition, when used as an electrode for a self-luminous element such as an organic EL element, the light extraction efficiency in the visible light short wavelength region can be improved.
Further, the transparent conductive film of the present invention is a substrate (room temperature to 100 ° C.) that needs to be formed at a low temperature using a sputtering method, particularly a direct current sputtering method, which is a thin film manufacturing method widely used industrially. There is also an advantage that it can be manufactured.

Hereinafter, embodiments of the present invention will be described. Prior to that, the background to the present invention and the features of the present invention will be described.
In order to solve such a problem, the present inventors have intensively studied various types of oxide films, and as a result, mainly composed of gallium, indium, and oxygen, and the atomic ratio of gallium to indium is 1 or more and less than 1.86, It is found that an amorphous oxide film preferably having a transmittance of 1.14 or more and less than 1.86 is a transparent conductive film having a shortest wavelength at which the transmittance of the film itself exhibits 50% is 350 nm or less, preferably 340 nm or less. It was. Furthermore, in order to obtain such a transparent conductive film, the generation of an indium oxide phase (In ₂ O ₃ phase) having a bixbyite structure that causes a decrease in light transmittance of the transparent conductive film at a wavelength of 400 nm or less is suppressed. The present inventors have found that it is necessary to form a film using a sputtering target that can be used, and have reached the present invention.

That is, it is mainly composed of gallium, indium, and oxygen, and the atomic ratio of gallium to indium is 0.97 or more and less than 1.86, preferably 1.14 or more and less than 1.86, and is mainly β-Ga ₂ O ₃ type. gallium oxide, indium-phase structure (beta-GaInO ₃ phase) and is composed of indium oxide phase bixbite type structure (an in ₂ O ₃ phase), and X-ray diffraction peak intensity ratio defined by the formula (1) is 45 %, Preferably 40% or less, and an oxide sintered body having a density of 5.8 g / cm ³ or more needs to be used as a sputtering target.
In ₂ O ₃ phase (400) / β-GaInO ₃ phase (111) × 100 [%] (1)
Thus, it was confirmed that an oxide transparent conductive film having a high light transmittance at a wavelength of 400 nm or less that can be applied to the above-described device can be formed. Moreover, it confirmed that the transparent conductive base material which formed this transparent conductive film not only on a glass substrate but on various transparent substrates, such as a resin film, has a high light transmittance with a wavelength of 400 nm or less.

That is, the first invention of the present invention is mainly composed of gallium, indium, and oxygen, and the atomic ratio of gallium to indium is 0.97 or more and less than 1.86, and mainly has a β-Ga ₂ O ₃ type structure. The X-ray diffraction peak intensity ratio defined by the formula (1) is 45% or less, which is composed of a gallium indium oxide phase (β-GaInO ₃ phase) and a bixbite type indium oxide phase (In ₂ O ₃ phase). An oxide film obtained by a direct current sputtering method using an oxide sintered body having a density of 5.8 g / cm ³ or more as a sputtering target, which is mainly composed of gallium, indium, and oxygen and The shortest wavelength at which the atomic ratio of gallium is 0.97 or more and less than 1.86, and the transmittance of the film itself excluding the substrate is 50%. To provide a transparent conductive film, characterized in that at 50nm or less.
In ₂ O ₃ phase (400) / β-GaInO ₃ phase (111) × 100 [%] (1)

  According to a second aspect of the present invention, the atomic ratio of gallium to indium in the sputtering target according to the first aspect is 1.14 or more and less than 1.86, and the X-ray diffraction peak intensity defined by the formula (1) The transparent conductive film according to the first invention is characterized in that the ratio is 40% or less, and the shortest wavelength at which the transmittance of the film itself excluding the substrate exhibits 50% is 340 nm or less.

According to a third aspect of the present invention, the transparent conductive film according to the first or second aspect is characterized in that the specific resistance value is 1.0 × 10 ^{−2 to} 5.0 × 10 ⁻¹ Ω · cm. I will provide a.

  According to a fourth aspect of the present invention, there is provided the transparent conductive film according to any one of the first to third aspects, wherein the arithmetic average height (Ra) is 1.0 nm or less.

  The fifth invention of the present invention is selected from a glass plate, a quartz plate, a resin plate or a resin film whose one or both sides are covered with a gas barrier film, or a resin plate or a resin film in which a gas barrier film is inserted. Provided is a transparent conductive substrate characterized in that the transparent conductive film according to any one of the first to fourth inventions is formed on one or both surfaces of the transparent substrate.

  In a sixth aspect of the present invention, the gas barrier film is at least one selected from a silicon oxide film, a silicon oxynitride (SiON) film, a magnesium aluminum oxide film, a tin oxide-based film, and a diamond-like carbon (DLC) film. A transparent conductive substrate according to the fifth invention, characterized in that it is of a kind.

  In a seventh aspect of the present invention, the material of the resin plate or resin film is polyethylene terephthalate (PET), polyethersulfone (PES), polyarylate (PAR), polycarbonate (PC), polyethylene naphthalate (PEN), Alternatively, the transparent conductive substrate according to the sixth or seventh invention is provided, which has a laminated structure in which the surface of these materials is covered with an acrylic organic material.

Hereinafter, although the transparent conductive film of this invention and the transparent conductive base material containing the same are demonstrated in detail, this invention is not limited to the following Example.
The transparent conductive film of the present invention is mainly composed of gallium, indium, and oxygen, and the atomic ratio of gallium to indium is 0.97 or more and less than 1.86, and is mainly gallium indium oxide having a β-Ga ₂ O ₃ type structure. Composed of a phase (β-GaInO ₃ phase) and a bixbite type indium oxide phase (In ₂ O ₃ phase), and an X-ray diffraction peak intensity ratio defined by the formula (1) is 45% or less, An oxide film obtained by a direct current sputtering method using an oxide sintered body having a density of 5.8 g / cm ³ or more as a sputtering target, mainly composed of gallium, indium, and oxygen, and gallium atoms with respect to indium An amorphous film having a ratio of 0.97 to less than 1.86, and the shortest wavelength at which the transmittance of the film itself excluding the substrate exhibits 50% is 350 nm. A transparent conductive film which is a lower.

In ₂ O ₃ phase (400) / β-GaInO ₃ phase (111) × 100 [%] (1)
Here, the indium oxide phase (In ₂ O ₃ phase) having a bixbyite structure may be one in which an oxygen deficiency is introduced or a part of In substituted with Ga. Further, the β-GaInO ₃ phase may be introduced with oxygen deficiency, or the atomic ratio of gallium to indium may be slightly deviated from the stoichiometric composition.

The sputtering target used for forming the transparent conductive film of the present invention is required to be an amorphous film and an oxide sintered body having an atomic ratio of gallium to indium of 0.97 or more and less than 1.86. When the atomic ratio of gallium to indium is less than 0.97, the shortest wavelength at which the transmittance of the film itself excluding the substrate exhibits 50% exceeds 350 nm. On the other hand, when the atomic ratio of gallium to indium is 1.86 or more, the specific resistance exceeds 5.0 × 10 ⁻¹ Ω · cm.

The sputtering target used for forming the transparent conductive film of the present invention needs to have an X-ray diffraction peak intensity ratio defined by the above formula (1) of 45% or less. If the X-ray diffraction peak intensity ratio exceeds 45%, the contribution of the indium oxide phase (In ₂ O ₃ phase) of the bixbite type structure of the sputtering target to the amorphous film is large. The shortest wavelength at which the transmittance of the membrane itself shows 50% exceeds 350 nm.
The density of the sputtering target needs to be 5.8 g / cm ³ or more. When the density of the sputtering target is less than 5.8 g / cm ³ , nodules and arc discharges occur during long-term use, and the film characteristics of the resulting amorphous transparent conductive film deteriorate.

  The transparent conductive film of the present invention is an amorphous film obtained by a direct current sputtering method. In this DC sputtering method, the negative voltage applied to the target is periodically stopped, and a low positive voltage is applied between them to neutralize positive charging with electrons (DC pulsing method). Is also included. It is possible to form a film while suppressing arcing in reactive sputtering using an oxygen reactive gas, and there is no need to control the impedance matching circuit unlike the high frequency sputtering method, and the film formation speed is higher than that of the high frequency sputtering method. Is also preferred because of its advantages such as fast.

The transparent conductive film of the present invention is a substrate (room temperature to 100) that needs to be formed at a low temperature by using a sputtering method, particularly a direct current sputtering method, which is a thin film manufacturing method widely used industrially as described above. ° C) has an advantage that it can be produced.
Furthermore, the transparent conductive film of the present invention has an X-ray diffraction peak intensity ratio defined by the above formula (1) of 40 when the atomic ratio of gallium to indium in the sputtering target is 1.14 or more and less than 1.86. %, Which is a transparent conductive film having a shortest wavelength of 340 nm or less at which the transmittance of the film itself excluding the substrate shows 50%.

The transparent conductive film of the present invention exhibits a specific resistance value of 5.0 × 10 ⁻¹ Ω · cm or less, and is 1.0 to 5.0 × 10 ⁻ applicable as an electrode of a device, depending on the type. ² Ω · cm can be obtained. For various uses such as an antistatic film, the amount of oxygen introduced during film formation can be controlled to be in the range of ˜1.0 × 10 ⁺⁸ Ω · cm. If a larger amount of oxygen is introduced, the insulating film can be made closer.

  In addition, the transparent conductive film of the present invention is characterized in that the arithmetic average height (Ra) is 1.0 nm or less. Here, the arithmetic average height (Ra) is based on the definition of JIS B0601-2001. When the arithmetic average height (Ra) exceeds 1.0 nm, it is not preferable in specific applications such as organic EL where flatness of the film surface is required.

The transparent conductive substrate of the present invention is made of a glass plate, a quartz plate, a resin plate or a resin film whose one or both sides are covered with a gas barrier film, or a resin plate or a resin film in which a gas barrier film is inserted. The transparent conductive film of the present invention is formed on one side or both sides of a selected transparent substrate. A thin film transistor (TFT) and a metal electrode for driving the thin film transistor (TFT) may be formed on the transparent substrate as long as the transparency of the substrate is not completely impaired.
Resin plates or resin films have higher gas permeability than glass plates, and light emitting layers of organic EL elements and inorganic EL elements and liquid crystal layers of LCDs and the like are deteriorated by moisture and oxygen. Is used as a substrate of these display elements, it is preferable to provide a gas barrier film that suppresses the passage of gas.

As the gas barrier film, it is preferable to form at least one film between the transparent substrate and the transparent conductive film. The gas barrier film preferably includes one or more of silicon nitride, silicon oxynitride, silicon oxide, and magnesium aluminate film. Further, the gas barrier film is not limited to an inorganic film, and may include an organic film.
The gas barrier film may be formed on one side of the resin plate or the resin film, and if it is formed on both sides, the gas passage blocking property is further improved. In addition, by forming the gas barrier film on one surface of the resin plate or the resin film and further laminating the resin plate or the resin film on the gas barrier film, a configuration in which the gas barrier film is inserted therein can be obtained. . Furthermore, it can also be set as the structure which repeated lamination | stacking several times.

The resin plate or resin film is made of polyethylene terephthalate (PET), polyethersulfone (PES), polyarylate (PAR), polycarbonate (PC), polyethylene naphthalate (PEN), or the surface of these materials. Although it is preferable to have a laminated structure covered with a hard coat layer typified by an acrylic organic material, it is not limited thereto. The thickness of the resin plate or resin film is appropriately selected according to the following specific application.
The gas barrier film is preferably at least one selected from a silicon oxide film, a silicon oxynitride (SiON) film, a magnesium aluminate film, a tin oxide film, and a diamond-like carbon (DLC) film.

Here, the tin oxide film has a composition containing at least one additional element selected from, for example, Si, Ce, Ge and the like in tin oxide. By these additive elements, the tin oxide layer is made amorphous to form a dense film. Further, at least one gas barrier film selected from a silicon oxide film, a silicon oxynitride film, a magnesium aluminum oxide film, a tin oxide film, and a diamond-like carbon film, and an organic or polymer film may be a resin substrate or The structure which gave the said transparent conductive thin film on the board | substrate of the structure laminated | stacked alternately on the surface of the resin film may be sufficient.
Such a transparent conductive film, when used as an electrode of a blue or near-ultraviolet LED or laser, or a device utilizing organic or inorganic EL, has a high light transmittance in the visible light short wavelength region or near ultraviolet region. Since it can be obtained, it is industrially useful. In addition, when used as an electrode for a self-luminous element such as an organic EL element, the light extraction efficiency in the visible light short wavelength region can be improved.

Hereinafter, the present invention will be described more specifically with reference to examples.
A gallium oxide powder and an indium oxide powder having a target production purity of 4N were each adjusted by ball milling to an average particle size of 3 μm or less. Then, it mix | blended so that the atomic ratio of the gallium with respect to an indium might become a desired ratio, and it mixed by the ball mill for 48 hours with the organic binder, the dispersing agent, and the plasticizer, and produced the slurry. The obtained slurry was spray-dried with a spray dryer to produce a granulated powder.
The obtained granulated powder was put in a rubber mold, and a molded body having a thickness of about 191 mmφ and a thickness of about 6 mm was produced by a hydrostatic press. The molded body obtained in the same manner was sintered under atmospheric pressure at an arbitrary temperature in an oxygen stream for 20 hours. Next, the sintered body was subjected to circumferential processing and surface grinding processing to obtain a shape having a diameter of about 15.24 cm (6 inches) and a thickness of about 5 mm. After processing, the sintered body was bonded to a cooled copper plate to obtain a sputtering target.

Production of Transparent Conductive Film A special SPF-530H made by Anelva was used as the sputtering apparatus. A synthetic quartz substrate was used as the substrate, and the substrate was placed parallel to the target surface. The distance between the substrate and the target was 60 mm.
The sputtering gas was a mixed gas composed of argon and oxygen, oxygen was set to a ratio of 1.0 to 2.0%, and the total gas pressure was set to 0.5 Pa. The input power was 200W. Film formation by DC magnetron sputtering was performed under the above conditions. The discharge was stable and no abnormalities such as arc discharge were found. The film formation time was adjusted according to the target to be used, and a 200 nm thick transparent conductive film was formed.

Target and Transparent Conductive Film Evaluation The atomic ratio of gallium to indium in the sintered body for the target and the obtained transparent conductive film was calculated from the weight of indium and gallium determined by ICP emission spectroscopy (using SPS4000 manufactured by Seiko Instruments Inc.). did.
The density of the sintered body was measured by the Archimedes method (using a high-precision automatic hydrometer manufactured by Toyo Seiki Seisakusho) using pure water.
The film thickness of the transparent conductive film was measured with a stylus type film thickness meter (Alpha-Step IQ manufactured by Tencor).
The specific resistance of the sintered body and the transparent conductive film was calculated from the surface resistance measured by the four-probe method (using Mitsubishi Chemical's LORESTA-IP, MCP-T250).
The light transmittance (T _{S + F} (%)) of the transparent conductive film including the substrate was measured with a spectrophotometer (U-4000, manufactured by Hitachi, Ltd.). The light transmittance (T _S (%)) of only the substrate was also measured under the same conditions, and (T _{S + F} / T _S ) × 100 was calculated as the light transmittance (T _F (%)) of the film itself.
The obtained X-ray diffraction pattern of the sintered body and the thin film was measured with an X-ray diffractometer (manufactured by Rigaku Denki Kogyo Co., Ltd., using CuKα rays). For the sintered body, the In ₂ O ₃ phase (400) and the β-GaInO ₃ phase (111) peak intensity were determined, and the In ₂ O ₃ phase (400) / β-GaInO ₃ phase (111) × 100 [%] The peak intensity ratio represented by The arithmetic average height (Ra) was measured with an atomic microscope (AFM, using Nanoscope III manufactured by Digital Instruments).

(Examples 1-3)
Indium oxide powder and gallium oxide powder were blended so that the atomic ratio of gallium to indium was 1.00, and a sputtering target was manufactured under three conditions of 1250 ° C, 1350 ° C, and 1400 ° C. Next, film formation was performed at room temperature using these three types of sputtering targets. The evaluation results of the target and the thin film are shown in FIG.
As shown in FIG. 1, when the sintering temperature of Example 1 is 1250 ° C., the density of the sintered body is 5.83 g / cm ³ , and the peak intensity ratio represented by the above formula (1) is 45%. Further, the atomic ratio of gallium to indium in the sintered body obtained by ICP emission spectroscopic analysis was 1.00. A transparent conductive film formed using this sintered body as a sputtering target exhibits a specific resistance of 3.4 × 10 ⁻² Ω · cm, the shortest wavelength at which the light transmittance of the film itself indicates 50% is 346 nm, and an arithmetic average The height (Ra) was 0.52 nm. As a result of X-ray diffraction measurement, it was confirmed that this transparent conductive film was amorphous.
That is, the sputtering target of Example 1 has a density of 5.8 g / cm ³ or more, and the peak intensity ratio represented by the above formula (1) is 45% or less. The transparent conductive film formed using this sputtering target is an amorphous film having a specific resistance value in the range of 1.0 × 10 ^{−2 to} 1.0 × 10 ⁺⁸ Ω · cm. It can be seen that the shortest wavelength at which the light transmittance of itself is 50% is 350 nm or less, and the arithmetic average height (Ra) is 1.0 nm or less.

Sintering temperature 1350 ° C in Example 2, even when the sintering temperature 1400 ° C in Example 3, respectively the density of the sputtering target 6.38 g / cm ^3, a 6.47 g / cm ^3, whereby It was confirmed that the formed transparent conductive film was amorphous. Other characteristics are shown in FIG.

(Examples 4 to 8)
Indium oxide powder and gallium oxide powder are blended so that the atomic ratio of gallium to indium is 0.97, 1.14, 1.21, 1.50, 1.85, and sputtering is performed at a sintering temperature of 1350 ° C. A target was produced. Next, film formation was performed at room temperature using these five types of sputtering targets. The sputtering target had a density of 5.8 g / cm ³ or more, and it was confirmed that the transparent conductive film formed by these sputtering targets was amorphous. The evaluation results of the target and the thin film are shown in FIG.
As can be seen from FIG. 2, the sputtering target has a density of 5.8 g / cm ³ or more as in Examples 1 to ³ , and the peak intensity ratio represented by the above formula (1) is 45% or less. The transparent conductive film formed by these sputtering targets has a specific resistance value in the range of 1.0 × 10 ^{−2 to} 5.0 × 10 ⁻¹ Ω · cm, and the light transmittance of the film itself is 50%. It can be seen that the shortest wavelength shown is 350 nm or less, and the arithmetic average height (Ra) is 1.0 nm or less.

Example 9
Using the sputtering target of Example 2, film formation was performed under the same conditions as in Example 2 except that the substrate temperature was changed to 200 ° C. The evaluation results are shown in FIG. Despite raising the substrate temperature to 200 ° C., it was confirmed by X-ray diffraction that the obtained film was an amorphous film. Further, this transparent conductive film has a specific resistance value in the range of 1.0 × 10 ^{−2 to} 5.0 × 10 ⁻¹ Ω · cm, and the shortest wavelength at which the light transmittance of the film itself exhibits 50% is 350 nm. It was confirmed that the arithmetic average height (Ra) was 1.0 nm or less.

(Examples 10 and 11)
Using the sputtering target of Example 7, film formation was performed under the same conditions as in Example 2 except that the oxygen flow rate ratio in the sputtering gas was changed to 3.0% and 5.0%. FIG. 4 shows the evaluation results. The specific resistance value of the obtained transparent conductive film increased with an increase in the oxygen flow rate ratio and exceeded the range of 1.0 × 10 ^{−2 to} 5.0 × 10 ⁻¹ Ω · cm. It was confirmed that it was in the range of 1.0 × 10 ^{−2 to} 1.0 × 10 ⁺⁸ Ω · cm suitable for such applications. Further, it was confirmed by X-ray diffraction that the obtained film was an amorphous film, the shortest wavelength at which the light transmittance of the film itself showed 50% was 350 nm or less, and the arithmetic average height (Ra) was 1. It was confirmed that the thickness was 0.0 nm or less.

(Example 12)
The same film formation as in Example 2 was performed except that a 100 μm thick PET film (Toyobo Co., Ltd.) was used as the substrate. As in Examples 1 to 11, it was confirmed by X-ray diffraction that the obtained transparent conductive film was an amorphous film, and the specific resistance value was 1.0 × 10 ^{−2 to} 5.0. It was confirmed that the shortest wavelength at which the light transmittance of the film itself was 50% was 350 nm or less and the arithmetic average height (Ra) was 1.0 nm or less in the range of × 10 ⁻¹ Ω · cm. .

(Example 13)
The same film formation as in Example 2 was performed except that a substrate with a barrier film in which a silicon oxynitride film was formed on one side of a 200 μm thick PES film (manufactured by Sumitomo Bakelite Co., Ltd.) was used. As in Examples 1 to 13, it was confirmed by X-ray diffraction that the obtained transparent conductive film was an amorphous film, and the specific resistance value was 1.0 × 10 ^{−2 to} 5.0. It was confirmed that the shortest wavelength at which the light transmittance of the film itself was 50% was 350 nm or less and the arithmetic average height (Ra) was 1.0 nm or less in the range of × 10 ⁻¹ Ω · cm. .

(Comparative Examples 1-3)
Indium oxide powder and gallium oxide powder were blended so that the atomic ratio of gallium to indium was 0.67, 0.96, and 2.00, and the sputtering temperature was 1350 ° C. to produce a sputtering target. Next, film formation was performed at room temperature using these three types of sputtering targets. The evaluation results of the target and the thin film are shown in FIG.
As is clear from FIG. 5, it can be seen that the sputtering targets of Comparative Examples 1 and 2 have a peak intensity ratio expressed by the above formula (1) exceeding 45%. The transparent conductive film formed by these sputtering targets has a low specific resistance value of 10 ⁻³ Ω · cm, but the shortest wavelength at which the light transmittance of the film itself exhibits 50% exceeds 350 nm. Further, it can be seen that in Comparative Example 1, the arithmetic average height (Ra) exceeds 1.0 nm.
Moreover, the sputtering target of Comparative Example 3 has a peak intensity ratio represented by the above formula (1) of 0%, but the Ga / In atomic ratio of the transparent conductive film formed by these sputtering targets is 1. .86 and a specific resistance value exceeding 5.0 × 10 ⁻¹ Ω · cm is not preferable. The shortest wavelength at which the transmittance is 50% is 350 nm or less.

(Comparative Examples 4 and 5)
Indium oxide powder and gallium oxide powder were blended so that the atomic ratio of gallium to indium was 1.00, and a sputtering target was produced under two conditions of 1100 ° C. and 1200 ° C. Next, film formation was performed at room temperature using these two types of sputtering targets. The evaluation results of the target and the thin film are shown in FIG.
As can be seen from FIG. 6, the sputtering targets of Comparative Example 4 and Comparative Example 5 have a sintered body density of less than 5.8 g / cm ³ . Further, structural analysis of the sputtering target of Comparative Example 4 was performed by X-ray diffraction measurement. As a result, when the sintering temperature was 1100 ° C., almost no β-GaInO ₃ phase was generated, and the (Ga, In) ₂ O ₃ phase. Only the In ₂ O ₃ phase was produced. Therefore, the In ₂ O ₃ phase (400) / β-GaInO ₃ phase (111) peak intensity ratio could not be obtained. It should be noted that the peak intensity of the In ₂ O ₃ phase (400) is higher than that of Example 2, and it is clear that a large amount of In ₂ O ₃ phase is generated. On the other hand, in the sputtering target of Comparative Example 5, it can be seen that the peak intensity ratio represented by the above formula (1) exceeds 45%.

When a film was formed using the target of Comparative Example 4, arc discharge occurred frequently during the film formation. Even when the target of Comparative Example 5 was used, although not as much as Comparative Example 4, arc discharge occurred frequently. That is, when a target sintered at 1100 ° C. and 1200 ° C. and having a density of less than 5.8 g / cm ³ is used, arc discharge frequently occurs during sputter film formation, resulting in film breakage and film formation speed. As a result, problems such as large fluctuations occurred, and there was a problem that stable film formation was impossible. Although the transparent conductive film formed by these sputtering targets has a specific resistance value on the order of 10 ⁻² Ω · cm, it can be seen that the shortest wavelength at which the light transmittance of the film itself exhibits 50% exceeds 350 nm. .

It is the table | surface which showed the evaluation result of the target and thin film in Examples 1-3. It is the table | surface which showed the evaluation result of the target and thin film in Examples 4-8. It is the table | surface which showed the evaluation result of the target in Example 9, and a thin film. It is the table | surface which showed the evaluation result of the target in Example 10 and 11, and a thin film. It is the table | surface which showed the evaluation result of the target and thin film in Comparative Examples 1-3. It is the table | surface which showed the evaluation result of the target and thin film in the comparative examples 4 and 5.

Claims (7)

It consists mainly of gallium, indium, and oxygen, and the atomic ratio of gallium to indium is 0.97 or more and less than 1.86, and is mainly a β-Ga ₂ O ₃ type gallium indium oxide phase (β-GaInO ₃ phase). And an indium oxide phase (In ₂ O ₃ phase) having a bixbyite structure, an X-ray diffraction peak intensity ratio defined by the formula (1) is 45% or less, and a density is 5.8 g / cm ³ or more. Is an oxide film obtained by a direct current sputtering method using an oxide sintered body as a sputtering target, and is mainly composed of gallium, indium, and oxygen, and the atomic ratio of gallium to indium is 0.97 or more and less than 1.86. And the shortest wavelength at which the transmittance of the film itself excluding the substrate exhibits 50% is 350 nm or less. Akirashirubedenmaku.
In ₂ O ₃ phase (400) / β-GaInO ₃ phase (111) × 100 [%] (1)   The atomic ratio of gallium to indium in the sputtering target according to claim 1 is 1.14 or more and less than 1.86, the X-ray diffraction peak intensity ratio defined by the formula (1) is 40% or less, and 2. The transparent conductive film according to claim 1, wherein the shortest wavelength at which the transmittance of the film itself excluding the substrate exhibits 50% is 340 nm or less. The transparent conductive film according to claim 1, wherein the specific resistance value is 1.0 × 10 ^{−2 to} 5.0 × 10 ⁻¹ Ω · cm.   Arithmetic mean height (Ra) is 1.0 nm or less, The transparent conductive film as described in any one of Claims 1-3 characterized by the above-mentioned.   On one or both sides of a transparent substrate selected from a glass plate, a quartz plate, a resin plate or resin film whose one or both sides are covered with a gas barrier film, or a resin plate or resin film in which a gas barrier film is inserted. A transparent conductive base material formed by forming the transparent conductive film according to any one of claims 1 to 4.   The gas barrier film is at least one selected from a silicon oxide film, a silicon oxynitride (SiON) film, a magnesium aluminate film, a tin oxide film, and a diamond-like carbon (DLC) film. Item 6. The transparent conductive substrate according to Item 5.   The resin plate or resin film material is polyethylene terephthalate (PET), polyethersulfone (PES), polyarylate (PAR), polycarbonate (PC), polyethylene naphthalate (PEN), or the surface of these materials is acrylic. The transparent conductive substrate according to claim 6 or 7, wherein the transparent conductive substrate has a laminated structure covered with an organic substance.

Images