JP2006160535A - Oxide sintered compact, sputtering target and transparent conductive thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent conductive thin film which is remarkably flat, low in resistance and is amorphous, an oxide sintered compact for stably forming the transparent conductive thin film and a sputtering target using the same. <P>SOLUTION: The oxide sintered compact comprises indium, tungsten, zinc and oxygen, tungsten in the amount of W/In of 0.004-0.034, zinc in the amount of Zn/In of 0.005-0.032 and silicon in the amount of Si/In of 0.007-0.052 each by the number of atoms, and has an indium oxide crystalline phase of a bixbyite structure as a main phase. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a transparent conductive thin film formed as an electrode in an organic electroluminescence (EL) element utilizing an organic substance, a transistor, a solar cell, a laser, and the like, and an oxide firing for producing the transparent conductive thin film. The present invention relates to a bonded target and a sputtering target using the oxide sintered body.

Since the transparent conductive thin film has high conductivity (for example, a specific resistance of 1 × 10 ⁻³ Ωcm or less) and high transmittance in the visible light region, it can be used for solar cells, display elements, and other various light receiving elements. In addition to being used for electrodes and the like, it is also used as a transparent heating element for various types of anti-fogging, such as a heat ray reflective film, an antistatic film and a freezer showcase for automobiles and buildings.

  In recent years, flat panel displays such as liquid crystal displays (LCDs) and plasma displays (PDPs) have become widespread as display elements using transparent conductive thin films. However, as next-generation flat panel displays, electroluminescence ( EL) devices are attracting attention.

  An EL element using a transparent conductive thin film has high visibility because of self-emission, and is excellent in impact resistance because it is a complete solid element. EL elements include an inorganic EL element using an inorganic compound as a light emitting material and an organic EL element using an organic compound as a light emitting material.

  Among these, the organic EL element has a feature that it is easy to downsize by greatly reducing the driving voltage. The structure of the organic EL element is based on a laminated structure of a transparent insulating substrate / anode (transparent electrode) / hole transport layer / light emitting layer / electron transport layer / cathode (metal electrode), and transparent insulation such as a glass plate. A bottom emission type in which a transparent conductive thin film is formed on a substrate and the transparent conductive thin film is used as an anode is usually employed.

  When a TFT (thin-film transistor) substrate is used as the transparent insulating substrate, the transparent insulating substrate / anode (metal electrode) / hole transport is used instead of the above-mentioned bottom emission type in order to increase the amount of extracted light. A top emission type having a laminated structure of layer / light emitting layer / electron transport layer / cathode (transparent electrode) has also been proposed.

  In addition to the organic EL elements, organic devices such as light-emitting elements, transistors, solar cells, and lasers have recently attracted attention as elements using transparent conductive thin films, as well as organic EL elements. .

Transparent conductive thin films used in these organic devices include tin oxide (SnO ₂ ) containing antimony and fluorine as dopants, zinc oxide (ZnO) containing aluminum and gallium as dopants, and oxide containing tin as dopants. Indium (In ₂ O ₃ ) and the like are widely used. Among these, an indium oxide film containing tin as a dopant (In ₂ O ₃ —Sn-based film) is referred to as an ITO (Indium Tin Oxide) film, and in particular, a low-resistance transparent conductive thin film can be easily obtained. Widely used.

  As a method for producing these transparent conductive thin films, a sputtering method is often used. The sputtering method is an effective method when film formation of a material having a low vapor pressure or precise film thickness control is required, and since the operation is very simple, it is widely used industrially. .

  The sputtering method used to manufacture the transparent conductive thin film uses a sputtering target as a raw material for the film component. Generally, the substrate is used as an anode and the sputtering target is used as a cathode under a gas pressure of about 10 Pa or less. As described above, a glow discharge is caused between them, an argon plasma is generated, an argon cation in the plasma is collided with a sputtering target of the cathode, and particles of a target component to be blown off by this are deposited on the substrate. A film is formed.

  Further, the sputtering method is classified according to the method of generating argon plasma, and includes a high frequency sputtering method using high frequency plasma and a direct current sputtering method using direct current plasma. There is also a magnetron sputtering method in which a magnet is disposed on the back side of a sputtering target so that plasma is concentrated directly on the sputtering target and the generation efficiency of argon ions is increased even at a low gas pressure. In general, the direct current sputtering method requires the use of a conductive target, but it is widely used industrially for reasons such as higher film formation speed, lower power supply facilities, and easier film formation operation than the high frequency sputtering method. Has been.

  However, although the ITO film used as the transparent conductive thin film has a low resistance, the crystallization temperature is as low as around 150 ° C., and irregularities are generated on the surface of the transparent conductive thin film without heating the substrate. Therefore, in the bottom emission type organic EL element, when an ITO film is used for the anode on the hole transport layer side, an overcurrent flows through the organic layer of the ultrathin film due to the unevenness of the surface, and black spots (dark Spot) occurs and contributes to the problem. When using an ITO film as the anode on the hole transport layer side, after forming the ITO film serving as the anode on the transparent insulating substrate, removing the surface irregularities by polishing or the like and smoothing the surface, the hole transport layer Laminate. In addition, in the top emission type organic EL element, when an ITO film is used for the cathode on the electron transport layer side, moisture and oxygen diffused through the grain boundary damage the organic layer on the base side. Although the lifetime is shortened, if the cathode is an amorphous film, moisture, oxygen and the like are difficult to diffuse. Therefore, a transparent electrode thin film having a smooth surface after film formation and amorphous and less diffusing moisture and oxygen is desired as an electrode.

Further, when forming a transparent conductive thin film on the organic layer, the organic layer is poor in heat resistance, so that it is impossible to form a film with heating. For this reason, a low resistance thin film is desired at low temperature. In the case of ITO, in order to obtain a low resistance film, crystallization must be promoted at a temperature higher than the crystallization temperature, and the mobility must be increased. When the film is formed at room temperature, the specific resistance is about 6 × 10 ⁻⁴ Ωcm.

  In the process of forming the transparent conductive thin film, regardless of whether it is a bottom emission type organic EL element or a top emission type organic EL element, a thin film (nodule) is generated on the sputtering target. Coarse particles are present inside. In the case of the bottom emission type, the organic layer cannot be deposited on the coarse particles, resulting in dark spots. In the case of the top emission type, coarse particles enter into the organic layer, and the coarse particles do not function. Therefore, in any case, the function as an element is deteriorated.

  For this reason, when manufacturing an ITO film | membrane by sputtering method, the sputtering target with few generation | occurrence | production of a nodule is desired. Regarding suppression of nodule generation in the production of an ITO film, it is known to increase the sintering density of the sputtering target, to control the pores in the sintered body, and to increase the strength of the sintered body. If these measures are taken, the generation of nodules in the sputtering target will certainly be reduced, but it cannot be completely suppressed, resulting in defects in the formed conductive thin film, which deteriorates the product yield. . Further, even if the sintering density of the sputtering target is increased, if a sintering crack occurs during sputtering, the probability of nodule generation at that portion is increased, so that the strength of the sintered body is preferably high.

  As described above, regardless of whether it is a bottom emission type or a top emission type, materials used for manufacturing an ITO film as a transparent conductive thin film of an organic EL element include surface smoothness, amorphous Quality, low resistance, etc. are required. Moreover, about a sputtering target, generation | occurrence | production suppression of a nodule is calculated | required. These requirements are the same for organic devices such as light emitting elements, transistors, solar cells, and lasers as devices that utilize organic substances in addition to organic EL elements.

  As for the indium oxide-based transparent conductive thin film, an indium oxide-based transparent conductive thin film containing additives other than tin has been studied, and several materials having characteristics not found in the ITO film have been found.

As a raw material for producing an indium oxide-based transparent conductive thin film, JP-A-61-136954 describes an indium oxide-based sintered body containing silicon oxide (SiO ₂ ) and / or germanium oxide (GeO ₂ ). In addition, in Japanese Patent Laid-Open No. 62-202415, Si is added by high frequency sputtering method and electron beam evaporation method using such an indium oxide-based sintered body containing silicon oxide and / or germanium oxide. A method for forming an indium oxide film or the like is described.

  According to this method, an Si-added indium oxide film or the like in which film defects are eliminated can be obtained, but even if a sputtering target obtained from the indium oxide-based sintered body is used, silicon oxide and / or Since germanium oxide is contained, this corresponds to the case where direct current sputtering is performed using a sputtering target in which a high-resistance material is contained in the base material of the conductive material. There is a problem that you can not.

  In addition, if a large amount of DC power is applied, charging of a high-resistance material is likely to occur, and the frequency of arcing during film formation increases. Therefore, it is difficult to obtain a high film formation speed by applying high power. .

  Furthermore, since the crystal structure of the obtained transparent conductive thin film is not specified, it is considered that a film having a smooth surface cannot be obtained by this method even if the film is formed by high frequency sputtering in pure argon gas. It is done.

On the other hand, Japanese Patent No. 3224396 describes a Zn-added In ₂ O ₃ film as a transparent conductive thin film used for an organic EL element. The Zn-added In ₂ O ₃ film tends to have an amorphous structure, and does not crystallize when heated to 200 ° C., for example, not only when the substrate temperature during film formation is room temperature. Therefore, it also has an advantage that a transparent conductive thin film excellent in surface smoothness can be stably produced.

  However, this has a problem that the transmittance in a short wavelength region, specifically, the transmittance at 400 nm is lower than that of ITO.

Japanese Patent Laid-Open No. 61-136954

JP-A-62-202415

Japanese Patent No. 3224396

  An object of the present invention is to provide a transparent conductive thin film that is extremely smooth, low in resistance, and amorphous, an oxide sintered body capable of stably forming the transparent conductive thin film, and sputtering using the same. It is to provide a target, and further to provide a transparent conductive thin film obtained by sputtering from the sputtering target.

  The oxide sintered body of the present invention is composed of indium, tungsten, zinc, silicon, and oxygen. Tungsten is 0.004 to 0.034 in W / In atomic ratio, and zinc is 0.00 in Zn / In atomic ratio. 005 to 0.032, silicon is contained at a Si / In atomic ratio of 0.007 to 0.052, and the main phase is an indium oxide crystal phase having a bixbyite structure.

Furthermore, the sintered density is desirably 6.5 g / cm ³ or more, and the average crystal grain size is desirably 5 μm or less.

  The sputtering target of the present invention is obtained by processing any one of the above oxide sintered bodies into a flat plate shape and bonding them to a cooling metal plate.

  The amorphous transparent conductive thin film of the present invention is made of indium, tungsten, zinc and silicon, tungsten is 0.004 to 0.034 in W / In atomic ratio, and zinc is 0 in Zn / In atomic ratio. 0.005 to 0.032, silicon is included in a ratio of 0.007 to 0.052 in terms of Si / In atomic ratio, and the balance is substantially made of indium and oxygen.

The specific resistance is desirably 5 × 10 ⁻⁴ Ωcm or less, and the average surface roughness (Ra) is desirably less than 1% of the film thickness.

  Furthermore, it is desirable that the transmittance at 400 nm exceeds 65%.

  Furthermore, it is desirable that a metal thin film of 3 nm to 5 nm is laminated.

  The organic EL element of the present invention uses any one of the above transparent conductive thin films.

  The organic device of the present invention uses any one of the above transparent conductive thin films.

  From a sputtering target using the oxide sintered body of the present invention, a transparent conductive thin film that is extremely smooth, low in resistance, and amorphous can be stably obtained by sputtering. Furthermore, by using the transparent conductive thin film as a light emitting element such as an organic EL element, an electrode of an organic device such as a transistor, a solar cell, and a laser, an organic device in which defects such as dark spots are suppressed can be provided. It becomes possible.

  As a result of intensive studies to solve the above problems, the present inventors have formed transparent conductive thin films having various compositions by a sputtering method, and the crystal structure, electrical characteristics, and optics of the obtained transparent conductive thin films. When the characteristics were examined, it was composed of indium, tungsten, zinc, silicon, and oxygen. Tungsten was 0.004 to 0.034 in W / In atomic ratio, and zinc was 0.005 to 0.00 in Zn / In atomic ratio. 032, when a sputtering target containing silicon in a proportion of 0.007 to 0.052 in terms of Si / In atomic ratio is used, the obtained transparent conductive thin film has surface smoothness, resistance, and crystallinity. It is suitable as a transparent conductive thin film of an EL element, and further, it has been found that no nodule is generated during sputtering, and the present invention has been completed. It was.

(Oxide sintered body)
The oxide sintered body for producing the transparent conductive thin film of the present invention comprises indium, tungsten, zinc, silicon and oxygen, and tungsten is 0.004 to 0.034 in terms of W / In atomic ratio, and zinc is Zn / Silicon is contained in a proportion of 0.005 to 0.032 in terms of In atom number and 0.007 to 0.052 in terms of Si / In atom number.

  In addition, the composition of the sputtering target produced from this oxide sintered compact and the transparent conductive thin film formed into a film using this sputtering target is substantially the same as the said oxide sintered compact.

Tungsten has an effect of increasing the crystallization temperature of the transparent conductive thin film and an effect of imparting conductivity, and the addition of tungsten makes the transparent conductive thin film amorphous. If the W / In atomic ratio is less than 0.004, the transparent conductive thin film will crystallize. On the other hand, if it exceeds 0.034, the specific resistance becomes 5 × 10 ⁻⁴ Ωcm or more.

Further, in the oxide sintered body, tungsten has an effect of hindering the growth of crystal grains of the oxide sintered body, and if the W / In atomic ratio is 0.004 or more, the average of the oxide sintered body The crystal grain size becomes very fine as 5 μm or less. When a sintering crack occurs during sputtering, nodules are likely to be generated in that portion. However, in the oxide sintered body of the present invention, the average crystal grain size is very small. Therefore, sintering cracks during sputtering that cause nodules produced from such an oxide sintered body hardly occur. On the other hand, if the W / In atomic ratio exceeds 0.034, W inhibits sintering, and the sintered density becomes less than 6.5 g / cm ³ . If the sintered density is low, it may cause nodules and the film formation rate during sputtering will be slow, which is not preferable in production.

  Zinc is added in the oxide sintered body for the purpose of imparting conductivity to the extent that direct current sputtering is possible and for raising the crystallization temperature. When the Zn / In atomic ratio of the oxide sintered body is less than 0.005, the film forming speed becomes very low, the productivity is inferior, and a low resistance and amorphous transparent conductive thin film is obtained. I can't. On the other hand, when the Zn / In atomic ratio exceeds 0.032, a transparent conductive thin film having excellent transmission characteristics cannot be obtained on the short wavelength side in the visible range (for example, near the wavelength of 400 nm).

  Silicon contributes to improvement of the crystallization temperature. When the Si / In atomic ratio of the oxide sintered body is less than 0.007, the crystallization temperature is low, and unevenness occurs on the film surface even when film formation is performed without heating. When the Si / In atomic ratio exceeds 0.052, the resistance of the obtained transparent conductive thin film increases.

(Manufacture of oxide sintered bodies)
In order to produce the oxide sintered body of the present invention, indium oxide powder, tungsten oxide powder, silicon oxide and zinc oxide powder having an average particle size of 0.1 μm to 3 μm or less are used as raw materials, and these are used at a predetermined ratio. Prepare with, put into a resin pot with water and mix with a wet ball mill. At this time, it is preferable to use a hard ZrO ₂ ball mill in order to avoid mixing impurities into the slurry as much as possible. The mixing time is preferably 10 hours to 30 hours. If it is shorter than 10 hours, the raw material powder is not sufficiently pulverized, and a stable high-density target cannot be obtained. If it is longer than 30 hours, it is excessively pulverized, and the particles are strongly agglomerated. A high-density target cannot be obtained. After mixing, the slurry is taken out, filtered, dried and granulated.

The granulated powder granulated to have an average particle size of about 25 μm to 100 μm was molded by applying a pressure of 196 MPa to 490 MPa ( ² ton / cm ^{2 to 5} ton / cm ² ) with a cold isostatic pressure (CIP) press. When the pressure is lower than 196 MPa ( ² ton / cm ² ), the density of the molded body does not increase, and a high-density target cannot be obtained. When the pressure exceeds 490 MPa (5 ton / cm ² ), the density of the molded body is increased. However, adjustment of conditions such as a process and equipment for obtaining the pressure increases, and the manufacturing cost increases.

Next, the obtained molded body was subjected to 1200 to 1500 ° C. for 10 to 30 hours in an atmosphere in which oxygen was introduced into the sintering furnace at a rate of 10 liters / minute per 0.01 m ^{3 of} the furnace volume. Sinter. If the temperature is lower than 1200 ° C., a high-density target cannot be stably obtained. If the temperature exceeds 1500 ° C., the crystal grain size increases or a reaction with the hearth plate occurs. When the treatment time is shorter than 10 hours, a high-density target cannot be stably obtained, and when it exceeds 30 hours, the crystal grain size becomes large.

  At the time of the sintering, it is preferable to perform the process up to 750 ° C. at about 0.5 ° C./min and the process from 750 ° C. to a predetermined sintering temperature at about 1 ° C./min. The reason for slowing the temperature rise is to make the temperature distribution in the furnace uniform. Further, after the completion of sintering, the introduction of oxygen was stopped, the temperature from the sintering temperature to 1300 ° C. was lowered at about 10 ° C./min, kept at 1300 ° C. for 3 hours, and then allowed to cool.

  When oxide is present in the oxide sintered body, abnormal discharge is likely to occur, and if a large amount of DC power is applied, charging of a high-resistance material is likely to occur, and the frequency of arcing during film formation increases. It is difficult to obtain a high film formation rate by introducing the same. However, when no oxide is present in the oxide sintered body and all the added elements are dissolved in the indium sites, the possibility of such a phenomenon is reduced. In the oxide sintered body of the present invention, by using indium oxide, tungsten oxide, silicon oxide, and zinc oxide having an average particle size of 0.1 μm to 3 μm or less as raw material powder, sufficient mixing and pulverization can be performed. The additive element can be replaced with an indium site. When the average particle diameter of the raw material powder is less than 0.1 μm, it is easy to dissolve, but the aggregation of the raw material powder becomes strong, and high density cannot be achieved. On the other hand, if it exceeds 3 μm, appropriate pulverization is not performed in the pulverization step, and coarse raw material powder exists in the granulated powder. When the raw material powder becomes non-uniform, sintering is not performed uniformly, high density cannot be achieved, diffusion of coarse oxide does not progress, and there is a problem that oxide exists in the oxide sintered body .

  The surface to be sputtered of the obtained oxide sintered body is polished with a cup grindstone or the like, processed to a thickness of about 3 mm to 10 mm, and bonded to a cooling metal plate (backing plate) such as an indium alloy and a sputtering target. did.

(Sputtering deposition)
In order to obtain the transparent conductive thin film of the present invention, the sputtering target of the present invention is used, the distance between target substrates during sputtering is set to 50 mm to 100 mm, the sputtering gas pressure is set to 0.5 Pa to 1.5 Pa, and the direct current magnetron is used. Film formation is performed by sputtering.

  When the distance between the target substrates is shorter than 50 mm, the kinetic energy of the sputtered particles deposited on the substrate is high, and the damage to the substrate is increased. For this reason, the film itself becomes a lower oxide and the resistance becomes high. Also, the film thickness distribution becomes worse. If it is longer than 100 mm, the film thickness distribution is improved, but the kinetic energy of the sputtered particles deposited on the substrate becomes too low, so that densification due to diffusion does not occur on the substrate, and only a transparent conductive thin film with low density can be obtained. Is not preferable.

  When the sputtering gas pressure is lower than 0.5 Pa, the kinetic energy of the sputtered particles deposited on the substrate is high, and the damage to the substrate increases. For this reason, the film itself becomes a lower oxide and the resistance becomes high. If it is higher than 1.5 Pa, not only the film formation rate is slowed, but also the kinetic energy of the sputtered particles deposited on the substrate becomes too low, and densification due to diffusion does not occur on the substrate. However, this is not preferable.

(Transparent conductive thin film)
The transparent conductive thin film of the present invention is composed of indium, tungsten, zinc, silicon and oxygen, and tungsten is 0.004 to 0.034 in W / In atomic ratio and zinc is 0.005 in Zn / In atomic ratio. .About.0.032, silicon is contained at a Si / In atomic ratio of 0.007 to 0.052. The transparent conductive thin film exhibits a low resistance of 5 × 10 ⁻⁴ Ωcm or less.

The transparent conductive thin film of the present invention exhibits a specific resistance of 5 × 10 ⁻⁴ Ωcm or less even when formed without heating. Therefore, it is possible to realize a top emission type organic EL that can be formed as an electrode on the organic light emitting layer and can efficiently extract light from the cathode as the upper surface electrode. Moreover, since it is possible to form a transparent electrode with low resistance and excellent surface smoothness on a low-temperature substrate, it can also be used as a cathode and / or an anode of a flexible transparent organic EL device using a resin film substrate. The industrial value is extremely high.

  The transparent conductive thin film of the present invention is completely amorphous and has a smooth surface, and the average roughness (Ra) of the surface is less than 1% of the film thickness. When used as a transparent conductive thin film, it may be desired to have a lower resistance. In this case, the resistance can be reduced by laminating metal thin films such as silver, silver alloy, aluminum or aluminum alloy. The thickness of the metal thin film is preferably 3 nm to 5 nm. When the metal thin film is thicker than 5 nm, the resistance value is lowered, but the transmittance is deteriorated. Conversely, if it is less than 3 nm, the continuity of the metal thin film is lost, and the effect of laminating the metal thin film cannot be exhibited.

Production of oxide sintered bodies (Examples 1 to 3, Comparative Examples 1 and 2)
As raw materials, In ₂ O ₃ powder (purity 99.99 mass%) with an average particle diameter of 0.1 μm to ₃ μm, WO ₃ powder (purity 99.99 mass%) with an average particle diameter of 0.1 μm to ₃ μm, average particle diameter SiO ₂ powder (purity 99.99 mass%) of 0.1 μm to 3 μm and ZnO powder (purity 99.99 mass%) having an average particle size of 0.1 μm to 3 μm were used.

Each powder was blended in a predetermined amount, put into a resin pot together with pure water, a dispersant, and a binder, and mixed for 20 hours using a wet ball mill using a hard ZrO ₂ ball mill. The mixed slurry was taken out, filtered, dried and granulated. The obtained granulated powder was molded by a cold isostatic press while applying a pressure of 294 MPa (3 ton / cm ² ).

Next, the obtained molded body was sintered at 1300 ° C. for 30 hours in an atmosphere in which oxygen was introduced into the sintering furnace at a rate of 10 liters / minute per 0.01 m ^{3 of} the furnace volume. At this time, the temperature was raised from 750 ° C. at 0.5 ° C./min and from 750 ° C. to 1300 ° C. at 1 ° C./min. After completion of the sintering, the introduction of oxygen was stopped, the temperature was lowered from 1300 ° C. to 1200 ° C. at 10 ° C./min, 1200 ° C. was maintained for 3 hours, and then allowed to cool. Thus, an oxide sintered body was obtained.

  The sintered density of the obtained oxide sintered body was determined by Archimedes method. The obtained oxide sintered body was subjected to thermal etching at 1300 ° C. and then observed with a scanning electron microscope (SEM) to obtain an average particle diameter.

  Table 1 shows the composition of the oxide sintered body obtained by the atomic ratio of tungsten, silicon and zinc to indium, the sintering temperature, and the sintered density and average particle diameter of the obtained oxide sintered body. Show.

As for the sintered density, in Comparative Example 2 where the W / In atomic ratio is 0.040, the sintered density is less than 6.5 g / cm ^3, and it is found that the sinterability deteriorates when the amount of W increases. It was. As for the average particle size, the effect of the W amount is large, and when the W / In atomic ratio is 0.003 or less as in Comparative Example 1, there is no problem in terms of the sintered density of the oxide sintered body. The average particle size was larger than 5 μm.

  The distribution state of the additive elements and the presence or absence of oxides in the oxide sintered bodies obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were measured with an electronic probe microanalyzer (EPMA) and an X-ray diffractometer (XRD). As a result of investigation, tungsten, silicon and zinc were uniformly dispersed, and the presence of these oxides was not recognized.

(Comparative Example 3)
Next, as raw materials, In ₂ O ₃ powder (purity 99.99 mass%) with an average particle diameter of 0.5 μm, WO ₃ powder (purity 99.99 mass%) with an average particle diameter of 6 μm, average particle diameter of 0.5 μm Sintered oxide in the same manner as in Examples 1 to 3 except that SiO ₂ powder (purity 99.99 mass%) and ZnO powder (purity 99.99 mass%) with an average particle size of 0.5 μm were used. The body was manufactured.

  When the distribution state of each element was investigated with an electronic probe microanalyzer (EPMA), 3 μm tungsten oxide larger than the crystal grain size of the oxide sintered body was observed. The presence of such a coarse oxide causes arcing and is not preferable in production. Since silicon and zinc were uniformly dispersed, it is considered that they were dissolved in the indium site.

Film formation (Examples 4 to 8, Comparative Examples 4 to 8)
Except that the composition was changed, the oxide sintered bodies of Examples 4 to 8 and Comparative Examples 4 to 8 were obtained in the same manner as in Example 1, and the sputter surfaces of the respective oxide sintered bodies were used as cup grindstones. Then, it was processed into a diameter of 152 mm and a thickness of 5 mm, and bonded to a backing plate using an indium alloy to obtain a sputtering target.

The sputtering target (2) is attached to the cathode for the non-magnetic target of the DC magnetron sputtering apparatus schematically shown in FIG. 1, and a # 7059 glass substrate having a thickness of 1.1 mm is provided on the opposite surface of the sputtering target (2). (4) was attached. The atmosphere is Ar + O ₂ , the total pressure is 0.6 Pa, O ₂ / (Ar + O ₂ ) × 100 = 2.5%, the distance between the target substrates is 70 mm, and the film thickness is formed on the glass substrate (4). A 200 nm transparent conductive thin film was formed. The substrate was not heated.

For Examples 4 and 5 and Comparative Example 4, the film formation rate was determined from the film formation time and the film thickness. Table 2 shows the composition, sintered density, and deposition rate of the oxide sintered body. The film thickness is marked on the glass substrate (4) with magic ink, the marked magic ink and the film deposited thereon are removed with acetone after film formation, and the resulting step is measured by contact type surface shape measurement. Obtained by measuring with a vessel (Dektak ³ ST).

  About Examples 6-8 and Comparative Examples 5-8, about the surface smoothness of the obtained transparent conductive thin film, an average roughness (Ra) was measured with an atomic force microscope, and a specific resistance was measured with a four-end needle method. did. Moreover, the composition of the transparent conductive thin film was determined with EPMA, and the light transmittance at 400 nm including the substrate was measured with a spectrophotometer (manufactured by Hitachi, Ltd., U-4000). Table 3 shows the composition, specific resistance, average roughness (Ra), and transmittance at 400 nm of the transparent conductive thin film.

  The crystallinity was also investigated with an X-ray diffractometer (XRD).

  In any of the transparent conductive thin films of Examples 4 to 8 of the present invention, no crystal peak was observed, and the film was amorphous.

  In Examples 4 and 5 in which the Zn / In atomic ratio of the oxide sintered body was 0.005 or more, the film formation rate increased to about 50 nm / s, which is equivalent to ITO.

  In Comparative Example 4 in which the Zn / In atomic ratio of the oxide sintered body is less than 0.005, the film formation rate is about half that of ITO, which is a very small value, which is not preferable for production.

  As in Comparative Example 5, when the W / In atomic ratio of the transparent conductive thin film exceeded 0.034, the specific resistance of the transparent conductive thin film rapidly increased, which was unsuitable as an electrode.

  On the other hand, as in Comparative Example 6, when the Si / In atomic ratio of the transparent conductive thin film is less than 0.007, the transparent conductive thin film crystallizes during sputtering, resulting in unevenness on the surface, A high average roughness (Ra) of 4 nm, which is 2 nm or more, which is 1% with respect to 200 nm of the film thickness was shown.

  For comparison, the ITO film was also measured in the same manner, but the average roughness (Ra) was 2.2 nm, showing an average roughness (Ra) of 2 nm or more, which is 1% of the film thickness of 200 nm. .

  As in Comparative Example 7, when the Zn / In atomic ratio of the transparent conductive thin film exceeded 0.032, the transmittance at 400 nm was 60% or less.

As in Comparative Example 8, when the Si / In atomic ratio exceeds 0.052, the specific resistance becomes higher than 5 × 10 ⁻⁴ Ωcm.

(Example 9, Comparative Example 9)
Lamination with an Ag film was attempted for the purpose of reducing resistance. On the first transparent conductive thin film having the same composition as that of Example 6 and having a thickness of 75 nm, an Ag layer was formed to 5 nm, and the second layer was formed in the same manner as the first transparent conductive thin film. The transparent conductive thin film was laminated with a thickness of 75 nm. When the specific resistance of the obtained laminated film was measured, it showed 5 × 10 ⁻⁵ Ωcm, and the specific resistance decreased by one digit.

  Similarly, on the first transparent conductive thin film having the same composition as that of Example 6 and having a thickness of 75 nm, an Ag layer was formed to 7 nm, and in the same manner as the first transparent conductive thin film. The second transparent conductive thin film was laminated with a thickness of 75 nm. Although the resistance value of the obtained laminated film was lowered, the transmittance at 550 nm was 87% and 90% or less.

It is the schematic of the direct current | flow magnetron sputtering apparatus used in the Example of this invention.

Explanation of symbols

1 Vacuum chamber 2 Target 3 DC power supply 4 Glass substrate 5 Supply pipe 6 Magnet

Claims (11)

  It consists of indium, tungsten, zinc, silicon and oxygen, tungsten is 0.004-0.034 in W / In atomic ratio, zinc is 0.005-0.032 in Zn / In atomic ratio, silicon is Si / An oxide sintered body containing an In atom ratio of 0.007 to 0.052 in terms of In atomic ratio and having a bixbite type indium oxide crystal phase as a main phase. The oxide sintered body according to claim 1, wherein the sintered density is 6.5 g / cm ³ or more.   The oxide sintered body according to claim 1 or 2, wherein the average crystal grain size is 5 µm or less.   A sputtering target, wherein the oxide sintered body according to any one of claims 1 to 3 is processed into a flat plate shape and bonded to a cooling metal plate.   Made of indium, tungsten, zinc and silicon, tungsten is 0.004-0.034 in W / In atomic ratio, zinc is 0.005-0.032 in Zn / In atomic ratio, silicon is Si / In atoms An amorphous transparent conductive thin film comprising a number ratio of 0.007 to 0.052 and the balance being substantially composed of indium and oxygen. The transparent conductive thin film according to claim 5, wherein the specific resistance is 5 × 10 ⁻⁴ Ωcm or less.   The transparent conductive thin film according to claim 5 or 6, wherein the surface has an average roughness (Ra) of less than 1% of the film thickness.   The transparent conductive thin film according to any one of claims 5 to 7, wherein the transmittance at 400 nm exceeds 65%.   A transparent conductive thin film in which a metal thin film of 3 nm to 5 nm is laminated on the transparent conductive thin film according to claim 5.   The organic electroluminescent element using the transparent conductive thin film in any one of Claims 5-9.   The organic device using the transparent conductive thin film in any one of Claims 5-9.

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