JP2012148937A - Electrically conductive composite oxide, zinc oxide type sintered body, method for manufacturing it and target - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zinc oxide type sintered body which is such a dense one that can obtain a transparent electrode which suppresses generation of abnormal electric discharge when used as a sputtering target, is excellent in production efficiency, and has a small specific resistance.SOLUTION: The zinc oxide type sintered body substantially comprises zinc, titanium and oxygen, and has a relative density of 95%, and the crystal phase comprises zinc oxide phase, electrically conductive composite oxide phase and low atomic value titanium phase. The zinc oxide type sintered body is obtained by molding a raw material powder including a mixed powder of titanium oxide powder and zinc oxide powder or zinc hydroxide powder, and/or zinc titanate compound powder, and then, sintering it at a temperature of 600-1,500°C in a reductive atmosphere or in an inert atmosphere.

Description

  The present invention relates to a conductive complex oxide, a zinc oxide-based sintered body, a method for producing the same, and a target used for a sputtering target or the like when forming zinc oxide to be a transparent electrode material by a sputtering method.

  Transparent conductive films that combine electrical conductivity and light transmission have been used as electrodes in solar cells, liquid crystal display elements, and other various light receiving elements, as well as automotive window and heat ray reflective films for buildings, It is used for a wide range of applications such as anti-static films and transparent heating elements for anti-fogging in frozen showcases. In particular, it is known that a transparent conductive film having low resistance and excellent conductivity is suitable for a solar cell, a liquid crystal display element such as a liquid crystal, organic electroluminescence, and inorganic electroluminescence, a touch panel, and the like.

A liquid crystal display, a solar cell, and the like use an electrode that is conductive and transparent to light (transparent electrode).
As materials having such properties, for example, oxide materials such as In ₂ O ₃ —SnO ₂ (ITO), ZnO—Al ₂ O ₃ (AZO), and ZnO—B ₂ O ₃ (BZO) are known. (For example, refer to Patent Documents 1 and 2). Such a material is formed as a thin film on a liquid crystal display or solar cell by sputtering, and then patterned as an electrode to become a transparent electrode.

  In the sputtering method, in a sputtering apparatus, a substrate (in this case, a liquid crystal display or the like) on which a thin film is to be formed and a sputtering target (hereinafter sometimes simply referred to as a target) are arranged to face each other. A gas discharge is generated between them, ions generated by the gas discharge collide with the surface of the target, and atoms (particles) released by the impact are attached to the opposing substrate to form a thin film.

  This target is formed of a material that becomes a thin film (transparent electrode), and the characteristics of the transparent electrode reflect the characteristics of the target. In general, the target is very expensive, and the price accounts for a large part of the manufacturing cost of the liquid crystal display or solar cell. For this reason, in order to reduce the cost of liquid crystal displays and solar cells, the target is also required to be inexpensive.

The ITO is tin (Sn) -doped indium oxide (In ₂ O ₃ ). When this ITO is used, the light transmittance is 85% or more, and the specific resistance is 1.0 · 10 ⁻⁴ Ω · A transparent electrode of about cm is obtained, and its characteristics are sufficient for use in liquid crystal displays and solar cells.
However, since indium (In) as a main component of the raw material is expensive, the target is expensive. In particular, when forming a large-area liquid crystal display or a transparent electrode for a solar cell, a target having a large area of the same level is required, which causes high costs. For this reason, a transparent electrode made of a lower cost material and having equivalent characteristics has been desired.

On the other hand, attempts have been made to dope ZnO with various dopants in order to increase conductivity, and an optimum doping amount and a minimum resistivity have been reported for each of the various dopants (see Non-Patent Document 1).
AZO and BZO are materials in which aluminum (Al) or boron (B), which is an n-type conductive additive, is added to zinc oxide (ZnO), which is a semiconductor, and is mainly composed of inexpensive zinc. It is superior to ITO in terms of low price.
Since sintered bodies made of these materials can be easily obtained in large areas, sputtering targets obtained by processing the sintered bodies are widely used.
A sintered body of BZO or AZO is obtained by blending raw material powder and sintering at a high temperature of 1000 ° C. or higher after molding.
As the raw material powder, ZnO powder as a main component and Al ₂ O ₃ powder or B ₂ O ₃ powder as an additive component are used. Similarly, ZnO—Ga ₂ O ₃ (GZO) or the like is also known as a zinc oxide-based material to which Ga ₂ O ₃ is added (see Patent Document 4).

  However, it is actually difficult to stably obtain a transparent electrode of BZO or AZO having a low specific resistance by using these targets, and the specific resistance is higher than that of ITO. The cause is mainly due to frequent occurrence of abnormal discharge in the sputtering apparatus during the sputtering. That is, during the sputtering of AZO, abnormal discharge frequently occurs, so that stable film formation is difficult. Further, when considering the production efficiency, the film forming apparatus is stopped every time an abnormal discharge occurs, so that the production efficiency is extremely poor and the production cost is increased.

This abnormal discharge occurs due to the fact that the target is non-uniform and there is a part where the specific resistance is locally different, and the impedance of the discharge system including the target fluctuates during sputtering. The fact that the specific resistance is locally different is common to zinc oxide based targets.
The crystal structure of the sintered body is mainly composed of zinc oxide wurtzite in which a part of the dopant is dissolved, and is composed of a composite oxide of the dopant and zinc oxide. Further, although it is not detected in XRD (X-ray diffraction), the dopant cannot be solid-phase sintered with zinc oxide, and is unsintered, that is, a trace amount of dopant oxide remains. Zinc oxide in which a part of the dopant is dissolved is conductive, but the composite oxide or the dopant oxide is an insulating layer, and therefore there is a portion where the specific resistance is greatly different locally in the target.

In the case of AZO, both Al ₂ O ₃ as a dopant oxide and ZnAl ₂ O _{4 as} a composite oxide are insulators. In the case of GZO, both the dopant oxide Ga ₂ O ₃ and the composite oxide ZnGa ₂ O ₄ are insulators. In the case of BZO, B ₂ O ₃ that is a dopant oxide and ZnB ₂ O ₄ that is a composite oxide are insulators.

  Therefore, aluminum, gallium, and boron are added as metals as the atomic species of the zinc oxide dopant, but solid-phase sintering does not proceed sufficiently between the zinc oxide and the metal, and the insulating property is low. Although the formation of complex oxides is also suppressed, there is a problem that the sintered density is extremely low.

Thus, in zinc oxide-based materials, it is inevitable that AZO, GZO, BZO, etc., which are known for their low resistance, have an insulating phase essentially locally in the oxide target. In order to alleviate the problem that production cannot be stably performed due to the occurrence of abnormal discharge due to these problems such as AZO, GZO, BZO, etc., and production efficiency is reduced, the density of the target is increased (Patent Document) (Refer to 3).
On the other hand, such zinc oxide-based conductive films (transparent electrodes) generally have low heat resistance and moisture resistance in air, that is, the resistivity may increase with time due to heat and humidity.

JP-A-11-302835 JP 2004-175616 A JP-A-7-258836 Japanese Patent Laid-Open No. 7-3443

Monthly Display, September 1999, p10 “Trends in ZnO-based transparent conductive films”

Conventionally, in a zinc oxide-based sputtering target, there was no insulating layer in the target, and there was no target having a sintered density of 95% or more. Therefore, abnormal discharge occurred and production efficiency was extremely low.
Therefore, it is desired to provide a zinc oxide-based sintered body in which an insulating layer does not exist at all in a sputtering target.

  On the other hand, if the low valence titanium oxide is already used as a zinc oxide donor source, the present inventors have further reduced resistance, excellent conductivity, and excellent transparency in the visible and near-infrared regions. It has been found to be excellent in chemical durability such as resistance and chemical resistance (alkali resistance, acid resistance). It is desired to provide a zinc oxide-based sintered body that is a sputtering target capable of maximizing the effect.

  Therefore, the present invention has been made in view of such problems, and can maximize the effects when low-valent titanium oxide is used as a donor source, and can stably produce a low-resistance thin film as a sputtering target. An object is to provide a zinc oxide-based sintered body that can be formed, a method for producing the same, and a zinc oxide-based sputtering target.

  That is, when the present invention is used for a sputtering target, since there is no insulating phase in the target and the sintered density is high, no abnormal discharge occurs, and a dense film that can be formed with extremely high production efficiency. An object of the present invention is to provide a zinc oxide-based sintered body having a small specific resistance, a method for producing the same, and a zinc oxide-based sputtering target.

As a result of intensive studies to solve the above problems, the present inventors have heretofore known that a composite oxide of zinc oxide and various elements is an insulator, but low valence titanium oxide and zinc oxide. It was newly found that the composite oxide sintered body produced from the above has conductivity. Therefore, when this knowledge is applied to a low-valent titanium oxide-doped zinc oxide-based sintered body (that is, when low-valent titanium oxide is used as a dopant), the sintered density is high and an insulating phase is present in the sputtering target. However, the present inventors have succeeded in producing a target that can significantly suppress the occurrence of abnormal discharge.
That is, the conductive composite oxide of the present invention is represented by the formula: Zn ₂ TiO ₄ , and ZnO and the low-valent titanium oxide represented by the general formula: TiO _{2 -X} (X = 0 to 1) It is produced from inert solid phase sintering with a molar ratio of 2: 1.

Furthermore, the inventors of the present invention have found that the crystal structure of a sintered body made from zinc oxide and low-valent titanium oxide includes a zinc oxide phase in which low-valent titanium is partly dissolved, a composite oxide (Zn ₂ TiO ₄ ) phase and low-valent titanium oxide that is not solid-phase sintered at a level that is not detected by XRD (X-ray diffraction). The present inventors have found that a target having excellent conductivity that does not exist can be formed, and the present invention has been completed.
That is, the zinc oxide-based sintered body of the present invention is a zinc oxide-based sintered body substantially composed of zinc, titanium, and oxygen, and has a relative density of 95% or more and a zinc oxide-based sintered body. The crystalline phase is composed of a zinc oxide phase, a conductive complex oxide phase, and a low-valent titanium oxide phase, and the conductive complex oxide phase is composed of Zn ₂ TiO ₄ .

In addition, the method for producing a zinc oxide-based sintered body according to the present invention includes a mixed powder of low-valent titanium oxide powder and zinc oxide powder or zinc hydroxide powder, and / or a raw material powder containing zinc titanate compound powder. After molding, the obtained molded body is sintered at 600 ° C. to 1500 ° C. in a reducing atmosphere or an inert atmosphere.
The target of the present invention is a target used for film formation by a sputtering method, an ion plating method, a pulse laser deposition (PLD) method or an electron beam (EB) vapor deposition method, and comprises the zinc oxide-based sintered body. It is characterized by that.

  The zinc oxide-based sintered body of the present invention is a dense sintered body, and the crystal phase is composed of zinc oxide in which titanium is partly dissolved, a conductive composite oxide, and low-valent titanium oxide. All components are electrically conductive. Therefore, when this zinc oxide-based sintered body is used as a sputtering target, there is an effect that an abnormal discharge does not occur and a transparent electrode having a small specific resistance can be obtained stably.

4 is a graph showing X-ray diffraction of zinc oxide-based sintered bodies obtained in Example 1 and Comparative Example 1, respectively. 4 is a graph showing X-ray diffraction of the zinc oxide-based sintered body obtained in Example 2. 4 is a graph showing X-ray diffraction of a zinc oxide-based sintered body obtained in Comparative Example 2. 6 is a graph showing X-ray diffraction of a zinc oxide-based sintered body obtained in Comparative Example 3.

  Hereinafter, an embodiment for carrying out the zinc oxide based sintered body of the present invention as a sputtering target will be described.

(Zinc oxide sintered body)
The zinc oxide-based sintered body of the present invention is an oxide sintered body substantially composed of zinc, titanium and oxygen, has a relative density of 95% or more, and the oxide phase has an oxidized crystal phase. It has the form which consists of a zinc phase, an electroconductive complex oxide phase, and a low valence titanium oxide phase.
Here, “substantially” means that 99% or more of all atoms constituting the oxide sintered body are composed of zinc, titanium, and oxygen.

  The zinc oxide phase is, for example, a ZnO crystal phase, a crystal phase in which a titanium element is dissolved in ZnO, a crystal phase in which oxygen deficiency is introduced into ZnO, or a zinc oxide deficiency resulting in a non-stoichiometric composition. Examples include a crystal phase. The zinc oxide phase usually has a wurtzite structure.

  The crystalline phase of ZnO alone does not exhibit electrical conductivity, but the crystalline phase of zinc oxide in which titanium partially dissolves in zinc sites exhibits electrical conductivity. Here, “part” usually refers to a state in which titanium is solid-dissolved in a zinc site at about 0.1 to 1 mol%.

The conductive complex oxide phase is a crystal phase substantially represented by the formula: Zn ₂ TiO ₄ . The conductive complex oxide phase made of Zn ₂ TiO _{4 is} made conductive by a solid phase sintering reaction in a reducing atmosphere or inert atmosphere of zinc oxide and low-valent titanium oxide for the first time. It has been found that Zn ₂ TiO ₄ can be produced.
In addition, the composite oxide phase specifically includes Zn ₂ TiO ₄ , those in which titanium element is dissolved in these zinc sites, those in which oxygen vacancies are introduced, and those having a Zn / Ti ratio. Non-stoichiometric compositions slightly deviating from these compounds are also included.

Zn ₂ TiO ₄ in the conductive complex oxide phase is produced by solid-phase sintering of ZnO and low-valent titanium oxide in an inert atmosphere at a molar ratio of ZnO: low-valent titanium oxide = 2: 1. Is done.
If not blended with ZnO: TiO = 2: 1 (molar ratio), Zn ₂ TiO ₄ is not a single phase and may be a mixture of ZnO and low-valent titanium oxide.

The low-valence titanium oxide phase is not only a crystal phase having an integer valence of TiO (II) and Ti ₂ O ₃ (III), but also a general formula: TiO _2-X (where X = 0 to It is a crystal phase in the range represented by 1). That is, the low valence titanium oxide phase in the present invention is a novel low valence titanium oxide phase represented by the chemical formula of the above general formula: TiO _{2 -X} . The structure of the low-valence titanium oxide phase can be confirmed by the results of instrumental analysis such as an X-ray diffractometer (X-ray diffraction, XRD) and an X-ray photoelectron spectrometer (XPS).

  In the zinc oxide-based sintered body of the present invention, the proportions of the zinc oxide phase, the conductive composite oxide phase, and the low-valent titanium oxide phase are such that the conductive composite oxide phase and part of titanium are solid from the viewpoint of conductivity. Since the conductivity increases in the order of dissolved zinc oxide and low-valent titanium oxide, it is preferable that the ratio of the phase having high conductivity is large.

The zinc oxide phase becomes a zinc oxide crystal phase in which titanium is partly dissolved in the zinc site, and exhibits conductivity. Some non-solid phase sintered low valence titanium oxides themselves have electrical conductivity.
Therefore, (i) a zinc oxide phase in which titanium is partly dissolved, (ii) a conductive complex oxide phase, and (iii) a low-valent titanium oxide phase constituting the zinc oxide-based sintered body obtained by the present invention Since each of them has conductivity, it can be a target with extremely excellent discharge stability, and it is extremely excellent in productivity and enables efficient production.
Here, the solid solution state means a low-valent titanium oxide, for example, a Ti atom such as Ti ₂ O ₃ , TiO or the like in a substitutional solid solution form in a ZnO crystal or the like. That is, the resistivity of the zinc oxide phase itself can be reduced by adopting this form. On the other hand, the composite oxide is different from the solid solution form in that conductivity is exhibited by introducing oxygen deficiency.

  Since all the components of the target itself have conductivity, the overall resistivity can be reduced, and a film can be formed at a low voltage. As a result, the voltage for accelerating oxygen ions toward the substrate is lowered, the collision energy of oxygen ions is reduced, damage to the thin film is reduced, and the specific resistance of the thin film can be lowered.

  The zinc oxide-based sintered body of the present invention is preferably composed of a zinc oxide phase, a composite oxide phase, and an unreacted low-valent titanium oxide phase. When the composite oxide phase is contained in the zinc oxide-based sintered body as described above, the strength of the zinc oxide-based sintered body increases, so that, for example, a film can be formed under severe conditions (high power, etc.) as a target. However, no cracks are generated.

The zinc oxide-based sintered body of the present invention has a relative density of 95% or more, preferably 98%. If the relative density is less than 95%, the sintered body itself is excellent in conductivity, but 5% or more voids exist, and therefore abnormal discharge may occur due to the voids as a starting point.
Also, in order to keep the relative density of the zinc oxide-based sintered body within the above range, as a method of manufacturing the sintered body, in the case of pressure sintering, the pressurizing pressure is increased and the sintering temperature is increased. What is necessary is just to raise sintering temperature in the case of normal pressure sintering.

(Method for producing zinc oxide-based sintered body)
The method for producing a zinc oxide-based sintered body of the present invention comprises a mixed powder of low-valence titanium oxide powder and zinc oxide powder or zinc hydroxide powder, and / or zinc titanate compound powder (conductive composite oxide powder). ), And then sintering the resulting molded body to obtain the above-described zinc oxide-based sintered body of the present invention.

  The raw material powder may be any powder containing titanium oxide powder, mixed powder of zinc oxide powder or zinc hydroxide powder, and / or zinc titanate compound powder. Low-valent titanium oxide powder and zinc oxide A mixed powder of powder or zinc hydroxide powder and zinc titanate compound powder may be used. Preferably, a powder containing a mixture of titanium oxide powder and zinc oxide powder or zinc hydroxide powder is preferable.

As the low-valent titanium oxide powder, for example, a low-valent titanium oxide powder such as titanium oxide (Ti ₂ O ₃ ) made of trivalent titanium or titanium oxide (TiO) made of divalent titanium is used. In particular, it is preferable to use TiO powder. This is because TiO has higher conductivity than Ti ₂ O ₃ and can increase the conductivity of the zinc oxide-based sintered body (target).
The low valence titanium oxide powder here is not only titanium oxide powder having an integer valence of TiO (II) and Ti ₂ O ₃ (III), but also Ti ₃ O ₅ and Ti ₄ O _7. , Ti ₆ O ₁₁ , Ti ₅ O ₉ , Ti ₈ O _15, etc., and a powder in a range represented by the general formula: TiO _{2 -X} (X = 0 to 1). The low-valent titanium oxide powder in the present invention is a novel low-valent titanium oxide represented by the general formula TiO _{2 -X} . The structure of the low valence titanium oxide can be confirmed by the results of instrumental analysis such as an X-ray diffractometer (X-Ray Diffraction, XRD) and an X-ray photoelectron spectrometer (XPS).

As the zinc oxide powder, a powder of ZnO or the like having a wurtzite structure is usually used, and a powder obtained by firing this ZnO in advance in a reducing atmosphere and containing oxygen deficiency may be used.
The zinc hydroxide powder may be either amorphous or crystalline.
As the zinc titanate compound powder, a conductive Zn ₂ TiO ₄ powder can be used, and Zn ₂ TiO ₄ produced by inert atmosphere solid-phase sintering of ZnO and the aforementioned low-valent titanium oxide powder. The powder is preferably used.
The average particle size of each compound (powder) used as the raw material powder is preferably 5 μm or less.

The oxide powder represented by the general formula: TiO _2-X (X = 0 to 1) is difficult to produce a single component, and is obtained as a mixture. Usually, it can be produced by heating titanium oxide (TiO ₂ ) in a reducing atmosphere such as a hydrogen atmosphere using carbon or the like as a reducing agent. By adjusting the hydrogen concentration, the amount of carbon as the reducing agent, and the heating temperature, the ratio of the low-valent titanium oxide powder mixture can be controlled.

  When using a mixed powder of low-valent titanium oxide powder and zinc oxide powder or zinc hydroxide powder as the raw material powder, or low-valent titanium oxide powder, zinc oxide powder or zinc hydroxide powder, and titanic acid When using mixed powder with zinc compound powder, the mixing ratio of each powder depends on the type of compound (powder) to be used. In the zinc oxide-based sintered body finally obtained, Ti / (Zn + Ti ) May be set as appropriate so that it is in the range of more than 0.02 and 0.1 or less. When the value of Ti / (Zn + Ti) is 0.02 or less, the doping effect of titanium is insufficient, the conductivity of the formed transparent conductive film is lowered, and the chemical durability improvement effect is insufficient. When the value of Ti / (Zn + Ti) exceeds 0.1, the impurity scattering factor during film formation increases, the mobility decreases, and the conductivity decreases.

  At that time, considering that zinc has a higher vapor pressure than titanium and is likely to volatilize when sintered, it is more than the desired composition of zinc oxide-based sintered body (atomic ratio of Zn and Ti). It is preferable to set the mixing ratio in advance so that the amount of zinc increases. Specifically, the easiness of volatilization of zinc varies depending on the atmosphere during sintering.For example, when zinc oxide powder is used, only the volatilization of zinc oxide powder itself occurs in an air atmosphere or an oxidizing atmosphere. When sintered in a reducing atmosphere, the zinc oxide is reduced and becomes metal zinc that is more easily volatilized than zinc oxide, so the amount of zinc lost increases (however, as described later, it is once sintered) After that, when annealing is performed in a reducing atmosphere, zinc is already difficult to evaporate because it is already a complex oxide at the time of annealing. Therefore, the amount of zinc to be increased with respect to the target composition may be set in consideration of the sintering atmosphere and the like. For example, when sintering in an air atmosphere or an oxidizing atmosphere, it is desirable. When the sintering is performed in a reducing atmosphere, the amount may be about 1.1 to 1.3 times the amount of the desired atomic ratio. In addition, each compound (powder) used as the raw material powder may be only one kind or two or more kinds.

The raw material powder may be pulverized before being molded. By performing the pulverization treatment, the raw material powder is adjusted to have a narrow particle size distribution, and can be uniformly solid-phase sintered in the sintering described later to obtain a high-density oxide sintered body. it can.
The method for pulverization is not particularly limited. For example, when media is used, a method using a pulverizer equipped with a bead mill, a ball mill, a planetary mill, a sand grinder, a vibration mill, or an attritor, and no media are used. Examples thereof include a method using a wet ultrahigh pressure atomizer such as a jet mill, a nanomizer, and a starburst.

The method for forming the raw material powder is not particularly limited. For example, the raw material powder and an aqueous solvent are mixed, and the resulting slurry is sufficiently mixed by wet mixing. What is necessary is just to dry and granulate and shape | mold the obtained granulated material.
The aqueous solvent contains water as a main component and may be water alone, or may be a mixture of water and alcohol such as methanol or ethanol.
The wet mixing may be performed by, for example, a wet ball mill using a hard ZrO ₂ ball or a vibration mill, and the mixing time when using the wet ball mill or the vibration mill is preferably about 12 to 78 hours. In addition, although raw material powder may be dry-mixed as it is, wet mixing is more preferable.

For solid-liquid separation / drying / granulation, known methods may be employed.
When the obtained granulated product is molded, for example, the granulated product is put into a mold, and a pressure of 1 ton / cm ² or more is applied using a cold molding machine such as a cold press or a cold isostatic press. Can be molded. At this time, if hot forming is performed using a hot press or the like, it is disadvantageous in terms of manufacturing cost and it may be difficult to obtain a large sintered body.

  Sintering of the obtained molded body is performed at 600 to 1500 ° C. in an inert atmosphere or a reducing atmosphere (for example, nitrogen, argon, helium, carbon dioxide, vacuum, hydrogen, etc.).

  The sintering temperature at the time of sintering in an inert atmosphere or a reducing atmosphere is 600 to 1500 ° C., preferably 1000 to 1300 ° C. If the sintering temperature is lower than 600 ° C., the sintering does not proceed sufficiently, so that the target density is lowered. On the other hand, if it exceeds 1500 ° C., zinc oxide itself is decomposed and disappears. When the molded body is heated to the sintering temperature, the rate of temperature increase is 5 to 10 ° C./min up to 600 ° C., and 1 to 4 ° C./min. It is preferable to make the sintered density uniform.

  When sintering in any atmosphere, the sintering time (that is, the holding time at the sintering temperature) is preferably 3 to 15 hours. If the sintering time is less than 3 hours, the sintered density tends to be insufficient, and the strength of the resulting zinc oxide-based sintered body tends to decrease. Grain growth tends to be significant, and the pores tend to become coarse, and hence the maximum pore diameter increases, and as a result, the sintered density may decrease.

  The method for performing the sintering is not particularly limited. For example, atmospheric pressure firing method, hot press method, hot isostatic pressing (HIP) method, cold isostatic pressing (CIP) The method, the microwave sintering method, the millimeter wave sintering method, etc. can be employed.

(target)
The target of the present invention is a target used for film formation by sputtering, ion plating, PLD, or EB vapor deposition. In addition, although the solid material used in the film formation may be referred to as “tablet”, in the present invention, these are referred to as “target”.

The target of the present invention is formed by processing the above-described zinc oxide-based sintered body of the present invention into a predetermined shape and a predetermined dimension as necessary.
A processing method in particular is not restrict | limited, What is necessary is just to employ | adopt a well-known method suitably. For example, after subjecting the zinc oxide-based sintered body to surface grinding or the like, the target of the present invention can be obtained by pasting the zinc oxide-based sintered body to a predetermined size and then attaching it to a support base. Further, if necessary, a plurality of zinc oxide-based sintered bodies may be divided into divided shapes to form a large-area target (composite target).

  The transparent conductive film formed using the zinc oxide-based sintered body of the present invention or the target of the present invention has excellent conductivity and chemical durability (heat resistance, moisture resistance, chemical resistance (alkali resistance, acid resistance). ) Etc.), for example, transparent electrodes such as liquid crystal displays, plasma displays, inorganic EL (electroluminescence) displays, organic EL displays, electronic papers, window electrodes of photovoltaic cells of solar cells, It is suitably used for applications such as electrodes of input devices such as transparent touch panels and electromagnetic shielding films of electromagnetic shields. Furthermore, the transparent conductive film formed using the zinc oxide-based sintered body of the present invention or the target of the present invention can be used as a transparent radio wave absorber, ultraviolet absorber, and transparent semiconductor device as another metal film or metal oxide. It can also be used in combination with a membrane.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by this Example.
In addition, evaluation of the obtained transparent conductive substrate was performed by the following method.

<Resistivity>
The specific resistance was measured by a four-terminal four-probe method using a resistivity meter (“LORESTA-GP, MCP-T610” manufactured by Mitsubishi Chemical Corporation). Specifically, four needle-shaped electrodes are placed on a straight line on the sample, a constant current is passed between the outer two probes, a constant current is passed between the inner two probes, and the inner two probes are The resulting potential difference was measured to determine the resistance.

<Surface resistance>
The surface resistance (Ω / □) was calculated by dividing the specific resistance (Ω · cm) by the film thickness (cm).

<Transmissivity>
The transmittance was measured using an ultraviolet-visible near-infrared spectrophotometer (“V-670” manufactured by JASCO Corporation).

<Moisture resistance>
The transparent conductive substrate was subjected to a moisture resistance test in which the transparent conductive substrate was held in an atmosphere at a temperature of 60 ° C. and a relative humidity of 90% for 1000 hours, and then the surface resistance was measured. It can be said that the surface resistance after the moisture resistance test is excellent in moisture resistance when the surface resistance before the moisture resistance test is twice or less.

<Heat resistance>
The transparent conductive substrate was subjected to a heat resistance test in which the transparent conductive substrate was held in the atmosphere at a temperature of 200 ° C. for 5 hours, and then the surface resistance was measured. When the surface resistance after the heat test is 1.5 times or less than the surface resistance before the heat test, it can be said that the heat resistance is excellent.

<Alkali resistance>
The transparent conductive substrate was immersed in a 3% NaOH aqueous solution (40 ° C.) for 10 minutes, and the presence or absence of a change in film quality on the substrate before and after immersion was confirmed visually.

<Acid resistance>
The transparent conductive substrate was immersed in a 3% aqueous HCl solution (40 ° C.) for 10 minutes, and the presence or absence of a change in film quality on the substrate before and after immersion was confirmed visually.

[Example 1]
Zinc oxide powder (ZnO powder; purity 99.9%, average particle size 1 μm or less, manufactured by Wako Pure Chemical Industries, Ltd.) and titanium oxide powder (TiO powder; purity 99.9%, average particle size 1 μm or less, ) Manufactured by High-Purity Chemical Laboratory) was mixed with ZnO: TiO = 2: 1 (molar ratio), mixed and dried in a ball mill for 20 hours to obtain a mixed powder.
After the mixing operation, the mixed powder obtained by removing the balls and ethanol is put into a mold (die) made of graphite, and vacuum-pressed at a pressure of 40 MPa with a punch made of graphite, followed by heat treatment at 1000 ° C. for 4 hours. The disc-shaped zinc oxide sintered body (1) was obtained.

When the obtained zinc oxide-based sintered body (1) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti. = 2: 1. The crystal structure of the zinc oxide-based sintered body (1) was examined using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation). The result is shown in FIG. As shown in FIG. 1, the zinc oxide-based sintered body (1) is a mixture of crystal phases of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ), and no TiO was detected. When the abundance ratio was analyzed, it was Zn ₂ TiO ₄ : ZnO = 89.7: 10.3.
Moreover, when the zinc oxide sintered body (1) was measured by SEM-EDX, most was Zn ₂ TiO ₄ and part was ZnO. Furthermore, an extremely small amount of non-solid phase TiO was detected.
The conductivity was measured with a tester and found to be 9Ω.
When the relative density of this zinc oxide-based sintered body (1) was calculated from the size of the sintered body, it was 95.2%. The relative density is obtained by multiplying the unit density of zinc oxide and titanium oxide by the weight ratio of mixing and taking the sum as a theoretical density of 100% (see the following formulas (A) and (B)).
Relative density = 100 × [(density of sintered body) / (theoretical density)] (A)
Theoretical density = (Zinc oxide simple substance density × mixing weight ratio + Titanium oxide simple substance density × mixing weight ratio) (B)

From these facts, it was found that Zn ₂ TiO ₄ occupying the majority has conductivity.

[Comparative Example 1]
Zinc oxide powder (ZnO powder; purity 99.9%, average particle size 1 μm or less, manufactured by Wako Pure Chemical Industries, Ltd.) and titanium oxide powder (TiO ₂ powder; purity 99.9%, average particle size 1 μm or less, ( Co., Ltd.) was blended with ZnO: TiO ₂ = 2: 1 (molar ratio), mixed and dried in a ball mill for 20 hours to obtain a mixed powder.
After the mixing operation, the mixed powder obtained by removing the balls and ethanol is put into a mold (die) made of graphite, and vacuum-pressed at a pressure of 40 MPa with a punch made of graphite, followed by heat treatment at 1000 ° C. for 4 hours. To obtain a disk-shaped zinc oxide-based sintered body (C1).
When the obtained zinc oxide-based sintered body (C1) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti. = 2: 1. The crystal structure of the zinc oxide-based sintered body (C1) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation). The result is shown in FIG. As shown in FIG. 1, the crystal structure of the zinc oxide-based sintered body (C1) is a mixture of crystal phases of zinc oxide (ZnO) and zinc titanate (Zn ₂ TiO ₄ ), and TiO ₂ is not detected. It was. When the abundance ratio was analyzed, it was Zn ₂ TiO ₄ : ZnO = 94.0: 6.0.
Further, measurement was performed of the zinc oxide-based sintered body (C1) at SEM-EDX, mostly a Zn ₂ TiO _4, part of which was ZnO. Furthermore, TiO _2, which is an extremely small amount of non-solid phase sintering, was detected.
When the conductivity was measured with a tester, no electricity flowed and it was an insulator.
When the relative density of the zinc oxide based sintered body (C1) was calculated in the same manner as in Example 1, it was 95.1%.

From these facts, it was found that Zn ₂ TiO ₄ obtained by solid phase sintering of ZnO and TiO ₂ occupying the majority was an insulator.

(Example 2)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and titanium oxide powder (TiO (III); manufactured by Kojundo Chemical Laboratory Co., Ltd., purity 99.99%) are used as raw material powders. A mixture of raw material powders was obtained by mixing at a Zn: Ti atomic ratio of 95: 5. After the mixing operation, the mixed powder obtained by removing the balls and ethanol is placed in a graphite mold (die), and vacuum-pressed at a pressure of 40 MPa with a graphite punch, and heated at 1100 ° C. for 4 hours. To obtain a disk-shaped zinc oxide sintered body (2) (hot pressing method).
It was 97.0% when the relative density of this zinc oxide type sintered compact (2) was computed from the size of a sintered compact. The relative density is obtained from the following formula. The obtained zinc oxide-based sintered body (2) was ground and polished to obtain a sintered body having a diameter of 50.8 mmΦ and a thickness of 3 mm.
Relative density = 100 × [(density of sintered body) / (theoretical density)]
However, theoretical density = (Zinc oxide simple substance density × mixing weight ratio + titanium oxide simple substance density × mixing weight ratio)

When the obtained zinc oxide-based sintered body (2) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ti was Zn: Ti. = 95: 5 (Ti / (Zn + Ti) = 0.05). The crystal structure of the zinc oxide-based sintered body (2) was examined using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation). The result is shown in FIG. As shown in FIG. 2, the crystal structure of the zinc oxide-based sintered body (2) is a mixture of crystal phases of zinc oxide (ZnO) and composite oxide (Zn ₂ TiO ₄ ), and titanium oxide (TiO) is It did not exist at all.
When the zinc oxide-based sintered body (2) was observed with SEM-EDX, most was ZnO and some was composite oxide (Zn ₂ TiO ₄ ). Furthermore, TiO, which is a very small amount of non-solid phase sintering, was present.
The constituent component of the zinc oxide-based sintered body (2) has electrical conductivity, and when the electrical conductivity of the entire target was evaluated by a tester, it was 10Ω.
When the relative density of the zinc oxide based sintered body (2) was calculated in the same manner as in Example 1, it was 98.9%.

The obtained sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target. Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 1000 nm was obtained.
Target size: 50.8 mmΦ x 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 45W
Deposition time: about 4 hours Substrate: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

When the discharge characteristics during the sputtering film formation were examined, abnormal discharge occurred twice during the film formation time (3 hours 40 minutes).
The composition (Zn: Ti) in the formed transparent conductive film is quantitatively analyzed using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation). As a result, Zn: Ti (atomic ratio) = 95: 5 (Ti / (Zn + Ti) = 0.05). The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of titanium into zinc, and further the crystal structure was examined using a field emission electron microscope (FE-SEM). Was found to be substituted and dissolved in zinc.
The specific resistance of the transparent conductive film on the obtained transparent conductive substrate was 4.0 · 10 ⁻⁴ Ω · cm, and the surface resistance was 4Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 85% in the visible region (380 nm to 780 nm) and an average of 85% in the infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the moisture resistance test was 1.2 times the surface resistance before the moisture resistance test, and the moisture resistance was excellent. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the heat test was 1.1 times the surface resistance before the heat test, and the heat resistance was excellent.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, it was found that there was no change in film quality before and after immersion, and the alkali resistance was excellent. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, it was found that after immersion, the film thickness was thin and dissolved, but the film quality did not change before and after immersion, and the acid resistance was excellent. It was.

  From the above, this target has a high density (relative density of 95% or more) and an insulating layer is not present in the target, so that the discharge stability is extremely excellent, and a film formed using this target is transparent. It is clear that the transparent conductive film has low resistance and also has chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance).

(Comparative Example 2)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and aluminum oxide powder (Al ₂ O ₃ ; Sumitomo Chemical Co., Ltd., purity 99.99%) are used as raw material powders, and these are Zn: Al Mixing was performed at a ratio of the atomic ratio of 95: 5 to obtain a mixture of raw material powders. After the mixing operation, the mixed powder obtained by removing the balls and ethanol is placed in a graphite mold (die), and vacuum-pressed at a pressure of 40 MPa with a graphite punch, and heated at 1100 ° C. for 4 hours. A disc-shaped zinc oxide sintered body (C2) was obtained (hot pressing method).
It was 97.0% when the relative density of this zinc oxide type sintered compact (C2) was computed from the size of a sintered compact. The relative density is obtained from the following formula. The obtained zinc oxide-based sintered body (C2) was ground and polished to obtain a sintered body having a diameter of 50.8 mmΦ and a thickness of 3 mm.
Relative density = 100 × [(density of sintered body) / (theoretical density)]
However, theoretical density = (Zinc oxide simple substance density × mixing weight ratio + Aluminum oxide simple substance density × mixing weight ratio)

When the obtained zinc oxide-based sintered body (C2) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Al was Zn: Al. = 95: 5 (Al / (Zn + Al) = 0.05). The results of measuring the crystal structure of this zinc oxide-based sintered body (C2) using an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation) are shown in FIG. As shown in FIG. 3, the crystal structure of the zinc oxide-based sintered body (C2) is a mixture of crystal phases of zinc oxide (ZnO) and composite oxide (ZnAl ₂ O ₄ ), and alumina oxide (Al ₂ O ₃ ) was not present at all.
When the zinc oxide-based sintered body (C2) was observed by SEM-EDX, most of the ZnO was ZnO in which a part of Al was dissolved, and a part was a composite oxide (ZnAl ₂ O ₄ ). Furthermore, there was an extremely small amount of Al ₂ O _{3 that} was non-solid phase sintering.
ZnO in which a part of Al is dissolved has conductivity, but the composite oxide (ZnAl ₂ O ₄ ) and a very small amount of non-solid-phase sintered Al ₂ O ₃ were completely insulating phases.
When the conductivity of the entire target was evaluated by a tester, the resistance was as low as 3Ω, but the entire surface was not a conductive layer, and an insulating layer existed in the conductive layer as a sea-island structure.

The obtained sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target. Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 1000 nm was obtained.
Target size: 50.8 mmΦ x 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 45W
Deposition time: about 4 hours Substrate: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

When the discharge characteristics during the sputtering film formation were examined, abnormal discharge occurred 9 times during the film formation time (3 hours 40 minutes).
The composition (Zn: Ti) in the formed transparent conductive film is quantitatively analyzed using a calibration curve by a fluorescent X-ray method using a wavelength dispersion type fluorescent X-ray apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation). As a result, Zn: Al (atomic ratio) = 95: 5 (Al / (Zn + Ti) = 0.05). The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of titanium into zinc, and further the crystal structure was examined using a field emission electron microscope (FE-SEM). Was found to be substituted and dissolved in zinc.
The specific resistance of the transparent conductive film on the obtained transparent conductive substrate was 3.4 · 10 ⁻⁴ Ω · cm, and the surface resistance was 3.4Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 85% in the visible region (380 nm to 780 nm) and an average of 70% in the infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the moisture resistance test was 2.8 times the surface resistance before the moisture resistance test, and it was found that the moisture resistance was inferior. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, the surface resistance after the heat test was 6.5 times the surface resistance before the heat test, and it was found that the heat resistance was poor.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, the film was completely dissolved and disappeared after immersion. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, the film was completely dissolved and disappeared.

  From the above, this target has a high density (relative density of 95% or more) and a low target resistance. However, since an insulating layer is present in the target, the discharge stability is inferior and a film is formed. And productivity is low. In addition, the film formed using this target has a low resistance, but is inferior in near-infrared transmittance and is a transparent conductive film inferior in chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance). It is clear that there is.

(Comparative Example 3)
Zinc oxide powder (ZnO; manufactured by Wako Pure Chemical Industries, Ltd., special grade) and alumina oxide powder (Ga ₂ O ₃ ; manufactured by Sumitomo Chemical Co., Ltd., purity 99.99%) are used as raw material powders, and these are Zn: Ga Were mixed at a ratio of 95: 5 to obtain a mixture of raw material powders. After the mixing operation, the mixed powder obtained by removing the balls and ethanol is placed in a graphite mold (die), and vacuum-pressed at a pressure of 40 MPa with a graphite punch, and heated at 1100 ° C. for 4 hours. To obtain a disk-shaped zinc oxide-based sintered body (C3) (hot pressing method).
When the relative density of this zinc oxide-based sintered body (C3) was calculated from the size of the sintered body, it was 97.0%. The relative density is obtained from the following formula. The obtained zinc oxide-based sintered body (C3) was ground and polished to obtain a sintered body having a diameter of 50.8 mmΦ and a thickness of 3 mm.
Relative density = 100 × [(density of sintered body) / (theoretical density)]
Theoretical density = (Zinc oxide simple substance density x mixing weight ratio + Gallium oxide simple substance density x mixing weight ratio)

When the obtained zinc oxide-based sintered body (C3) was analyzed with an energy dispersive X-ray fluorescence apparatus (“EDX-700L” manufactured by Shimadzu Corporation), the atomic ratio of Zn and Ga was Zn: Ga. = 95: 5 (Ga / (Zn + Ga) = 0.05). The crystal structure of the zinc oxide-based sintered body (C3) was examined with an X-ray diffractometer (“RINT2000” manufactured by Rigaku Corporation). The result is shown in FIG. As shown in FIG. 4, the crystal structure of the zinc oxide-based sintered body (C3) is a mixture of crystal phases of zinc oxide (ZnO) and composite oxide (ZnGa ₂ O ₄ ), and gallium oxide (Ga ₂ O ₃ ) was not present at all.
When the zinc oxide-based sintered body (C3) was observed with SEM-EDX, most of the ZnO was ZnO in which Ga was partly dissolved, and some was composite oxide (ZnGa ₂ O ₄ ). Furthermore, there was an extremely small amount of Ga ₂ O _{3 which} was non-solid phase sintering.
Although ZnO in which a part of Ga is dissolved has conductivity, the composite oxide (ZnGa ₂ O ₄ ) and a very small amount of non-solid phase sintered Ga ₂ O ₃ were completely insulating phases.
When the conductivity of the entire target was evaluated by a tester, the resistance was as low as 2Ω, but the entire surface was not a conductive layer, and an insulating layer existed as a sea-island structure in the conductive layer.

The obtained sintered body was bonded using indium solder using a copper plate as a backing plate to obtain a sputtering target. Using the obtained sputtering target, a film was formed by sputtering. The sputtering conditions were as follows, and a thin film having a thickness of about 1000 nm was obtained.
Target size: 50.8 mmΦ x 3 mm thickness Sputtering device: “E-200S” manufactured by Canon Anelva
Sputtering method: DC magnetron sputtering Ultimate vacuum: 2.0 × 10 ⁻⁴ Pa
Ar pressure: 0.5 Pa
Substrate temperature: 200 ° C
Sputtering power: 45W
Deposition time: about 4 hours Substrate: Soda lime glass (50.8 mm x 50.8 mm x 0.5 mm)

When the discharge characteristics during the sputtering film formation were examined, abnormal discharge occurred 9 times during the film formation time (3 hours 40 minutes).
The composition (Zn: Ga) in the formed transparent conductive film is quantitatively analyzed using a calibration curve by a fluorescent X-ray method using a wavelength dispersive X-ray fluorescence apparatus (“XRF-1700WS” manufactured by Shimadzu Corporation). As a result, Zn: Ga (atomic ratio) = 95: 5 (Ga / (Zn + Ga) = 0.05). The transparent conductive film is subjected to X-ray diffraction using an attachment for thin film measurement using an X-ray diffractometer ("RINT2000" manufactured by Rigaku Corporation) and an energy dispersive X-ray microanalyzer (TEM-). EDX) was used to investigate the doping state of gallium into zinc, and the field structure electron microscope (FE-SEM) was used to examine the crystal structure. Was found to be substituted and dissolved in zinc.
The specific resistance of the transparent conductive film on the obtained transparent conductive substrate was 3.6 · 10 ⁻⁴ Ω · cm, and the surface resistance was 3.6Ω / □. The specific resistance distribution on the transparent substrate was uniform in the plane.
The transmittance of the obtained transparent conductive substrate was an average of 85% in the visible region (380 nm to 780 nm) and an average of 70% in the infrared region (780 nm to 1500 nm). The transmittance in the visible region (380 nm to 780 nm) of the quartz glass substrate before film formation was 94% on average, and the transmittance in the infrared region (780 nm to 2700 nm) was 94% on average.
When the moisture resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the moisture resistance test was 2.4 times the surface resistance before the moisture resistance test, and the moisture resistance was inferior. Moreover, when the heat resistance of the obtained transparent conductive substrate was evaluated, it was found that the surface resistance after the heat test was 5.5 times the surface resistance before the heat test, which is inferior in heat resistance.
When the alkali resistance of the obtained transparent conductive substrate was evaluated, the film was completely dissolved and disappeared after immersion. Moreover, when the acid resistance of the obtained transparent conductive substrate was evaluated, the film was completely dissolved and disappeared.

  From the above, this target has a high density (relative density of 95% or more) and a low target resistance. However, since an insulating layer is present in the target, the discharge stability is inferior and a film is formed. And productivity is low. In addition, the film formed using this target has a low resistance, but is inferior in near-infrared transmittance and is a transparent conductive film inferior in chemical durability (heat resistance, moisture resistance, alkali resistance, acid resistance). It is clear that there is.

Claims (8)

ZnO and low-valent titanium oxide represented by the general formula: TiO _{2 -X} (X = 0 to 1) are produced from inert solid-phase sintering with a molar ratio of 2: 1 and have the formula: Zn ₂ TiO ₄ A conductive complex oxide represented by An oxide sintered body substantially consisting of zinc, titanium and oxygen,
The relative density is 95% or more, and the crystalline phase of the oxide sintered body is composed of a zinc oxide phase, a conductive composite oxide phase, and a low-valent titanium oxide phase, and the conductive composite oxide phase is Zn ₂ TiO. _A zinc oxide-based sintered body comprising 4. 3. The zinc oxide-based sintered body according to claim 2, wherein the conductive complex oxide phase Zn ₂ TiO ₄ is produced from inert solid-phase sintering in which ZnO and low-valent titanium oxide have a molar ratio of 2: 1. The zinc oxide-based sintering according to claim 2 or 3, wherein the low-valent titanium oxide phase is a phase comprising a low-valent titanium oxide represented by a general formula: TiO2 _-X (X = 0 to 1). body.   A method for producing a zinc oxide-based sintered body according to any one of claims 2 to 4, comprising a mixed powder of low-valent titanium oxide powder and zinc oxide powder or zinc hydroxide powder, and / or titanic acid. A method for producing a zinc oxide-based sintered body, comprising molding a raw material powder containing a zinc compound powder and then sintering the obtained molded body at 600 ° C to 1500 ° C in a reducing atmosphere or an inert atmosphere. The method for producing a zinc oxide-based sintered body according to claim 5, wherein the titanium oxide powder is a low-valent titanium oxide powder represented by a general formula: TiO2 _-X (X = 0 to 1).   The zinc oxide-based sintered body according to claim 5 or 6, wherein the reducing atmosphere or inert atmosphere is an atmosphere made of at least one selected from the group consisting of nitrogen, argon, helium, carbon dioxide, vacuum and hydrogen. Manufacturing method.   A target used for film formation by a sputtering method, an ion plating method, a pulse laser deposition (PLD) method, or an electron beam (EB) vapor deposition method, and the zinc oxide-based firing according to any one of claims 2 to 4 A target characterized by comprising a ligature.

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