JP2021134095A - Oxide sintered compact, method for producing the same, and sputtering target - Google Patents

Abstract

To provide an oxide sintered compact for a sputtering target or ion plating tablet which allows for continuous film-formation, a method for producing the same, and a sputtering target.SOLUTION: This oxide sintered compact contains Bi, V, W, and oxygen, the contained amount of Bi is 1.05 to 1.30 in terms of Bi/(V+W) atom ratio, the contained amount of W is 0.01 to 0.05 in terms of W/(V+W) atom ratio, and a crystal phase of scheelite type crystal structure and a crystal phase of aurivillius type crystal structure are contained. This oxide sintered compact contains Bi component in excess. When producing a Bi(V,W)O4 film having a photocatalytic function by using a target made from the sintered compact, even if the bismuth oxide component having high vapor pressure volatilizes from the film film-formed in the vacuum during film-formation, the Bi component contained in excess is continuously supplied from the sintered compact. As a result, it becomes possible to continuously produce Bi(V,W)O4 film of bismuth deficient-free stoichiometric composition.SELECTED DRAWING: None

Description

The present invention relates to an oxide sintered body for a sputtering target or an ion plating tablet used when an oxide film of bismuth and another metal is produced by a sputtering method or an ion plating method, and particularly. The present invention relates to an oxide sintered body for a sputtering target or an ion plating tablet capable of continuous film formation.

There is an urgent need to develop a photocatalyst that makes effective use of solar energy to produce hydrogen and oxygen from water. Among them, BiVO ₄ (bismuth vanadium acid) and Bi (V, W) O ₄ are attracting attention as photocatalysts that efficiently decompose water to generate oxygen under visible light irradiation.

These photocatalysts are used, for example, in a state where the powder is dispersed in water, the powder is transferred to a metal substrate and used as a film (photocatalyst film), processed into a sintered body shape, and used as a photocatalyst sheet. Has been done. It is generally said that a photocatalyst exhibits high activity when its crystal face is formed in a clean state with few defects.

By the way, as a method for manufacturing a coating film, chemical vapor deposition method (CVD method) and physical vapor deposition method (PVD method) have been constructed in the manufacturing fields of flat panel displays, solar cells, semiconductors, and the like. There is. Further, among the PVD methods, the sputtering method is useful as a method for producing a large-area and uniform deposition film, and a high-quality and highly crystalline deposit film is produced by utilizing plasma generated in vacuum. Therefore, it is widely used in the above-mentioned manufacturing fields.

Then, in Patent Document 1, as a method for producing a base material coated with an oxide [for example, BiVO ₄ or Bi (V, W) O _{4 or the like] film of bismuth and another metal, a sputtering technique is used.} A method for coating an oxide film is disclosed, and for example, a sputtering technique using an oxide sintered body obtained by firing a molded product made of _{BiVO 4 powder as a sputtering target is disclosed (Patent Document 1).} See examples).

However, it is difficult to continuously produce a _{BiVO 4} film by the sputtering technique described in Patent Document 1 in which an oxide sintered body obtained by firing a molded body made of _{BiVO 4 powder is used as a sputtering target.} There was a problem that a coating (deposited) film lacking a bismuth atom was produced from the chemical quantitative composition, and it became difficult to fully exhibit the photocatalytic performance of the coated (deposited) film.

Japanese Patent Application Laid-Open No. 2012-532985 (see paragraphs 0033-0038)

The present invention has been made by paying attention to such a problem, and the subject thereof is the sputtering method or ion plating of _{an oxide [Bi (V, W) O 4] film of bismuth and another metal.} It is an oxide sintered body for a sputtering target or an ion plating tablet used when manufacturing by the ting method, and can continuously form a film without losing bismuth atoms from the chemical quantitative composition. An object of the present invention is to provide an oxide sintered body for a sputtering target or an ion plating tablet and a method for producing the same, and to provide a sputtering target obtained by processing the oxide sintered body.

Therefore, in the sputtering technique described in Patent Document 1, the present inventor diligently analyzed the cause of the production of a coating (deposited) film lacking bismuth atoms from the chemical quantitative composition, and found that the vapor pressure of the bismuth oxide component was found. I came to discover that I was involved. That is, since the vapor pressure of the bismuth oxide component is high, the bismuth oxide component volatilizes from _{the coating [BiVO 4} , Bi (V, W) O _{4, etc.] film formed by sputtering in the vacuum at the time of film formation.} This was because a coating (deposited) film lacking bismuth atoms was produced from the chemical composition. Therefore, in the present invention, the above-mentioned problems are solved by adopting a method of adding an excess of a bismuth component to the oxide sintered body.

That is, the first invention according to the present invention is
It contains bismuth, vanadium, tungsten, and oxygen, and the content of bismuth is 1.05 to 1.30 in terms of bismuth / (vanadium + tungsten) atomic number ratio, and the content of tungsten is tungsten / (vanadium + tungsten) atom. It is characterized by having a numerical ratio of 0.01 to 0.05 and including a crystal phase having a sealite type crystal structure and a crystal phase having an auribilias type crystal structure.
The second invention is
In the oxide sintered body according to the first invention,
It is characterized in that it does not contain the bismuth oxide phase, or even if it contains the bismuth oxide phase, its particle size is less than 1 μm.
Moreover, the third invention is
In the oxide sintered body according to the first invention or the second invention.
It is characterized in that the tungsten oxide phase is not contained, or even if the tungsten oxide phase is contained, the particle size is less than 1 μm.

Next, the fourth invention according to the present invention is
The first invention- In the method for producing an oxide sintered body according to any one of the third inventions.
The average particle size of the bismuth raw material powder, the vanadium raw material powder, and the tungsten raw material powder is 1 μm or less.
The fifth invention is
In the sputtering target
It is characterized in that it is obtained by processing the oxide sintered body according to any one of the first invention to the third invention.

According to the oxide sintered body according to the present invention.
The bismuth content is 1.05 to 1.30 in the bismuth / (vanadium + tungsten) atomic number ratio, and the tungsten content is 0.01 to 0.05 in the tungsten / (vanadium + tungsten) atomic number ratio. At the same time, it contains a crystal phase with a sealite type crystal structure and a crystal phase with an auribilias type crystal structure.
The bismuth component is excessively contained as compared with the oxide sintered body of Patent Document 1 produced by firing a molded product made of _{BiVO 4 powder or the like.}

_{Therefore, even if the bismuth oxide component volatilizes from the Bi (V, W) O 4} film formed by sputtering in the vacuum at the time of film formation, the bismuth component contained in excess from the oxide sintered body should be continuously supplied. Therefore, it is possible to continuously produce a Bi (V, W) O _{4 film in which the bismuth atom is not deleted.}

Hereinafter, embodiments of the present invention will be described in detail.

(1) Sputtering method In the sputtering method, generally, a sputtering target made of an oxide sintered body containing a constituent metal of a film is used as an anode under an atmospheric gas pressure of about 10 Pa or less. (Hereinafter, it may be abbreviated as a target) is used as a cathode, and an argon plasma is generated by causing a glow discharge between them, and the argon cation in the plasma is made to collide with the sputtering target of the cathode to be repelled. The blown particles (sputtered particles) are deposited on the substrate to form a thin film.

Industrially, the magnetron sputtering method, in which a magnet is placed on the back surface of the target cathode (cathode), a dense plasma region is created by the effect of the magnetic field emitted on the target surface, and the amount of argon ions generated is increased to increase the film formation rate. Is often used. In the magnetron sputtering method, the target surface directly under the dense plasma region formed by the magnetic field is irradiated with the largest amount of argon ions and becomes a consumed portion, and the consumed portion is called "erosion". The composition of the sputtered particles that are blown onto the substrate, which is the film-deposited body, generally matches the composition of the "erosion" portion on the target surface. Further, the substrate may be formed in a non-heated state, or the substrate may be formed in a heated state. In many cases, the substrate is heated in order to produce a good quality crystal film.

Further, the sputtering method is classified by the method of generating argon plasma, the method using high frequency plasma is called "high frequency sputtering method", and the method using DC plasma is called "DC sputtering method". In general, the "DC sputtering method" is widely used industrially because the film forming speed is faster than the "high frequency sputtering method", the power supply equipment is inexpensive, and the film forming operation is easy. However, while the "high frequency sputtering method" can form a film even with an insulating sputtering target, the "DC sputtering method" requires the use of a conductive sputtering target. When a magnetron is used, it is called a "DC magnetron sputtering method" or a "high frequency magnetron sputtering method".

(2) Oxide sintered body In film formation (manufacturing) of an oxide film by a sputtering method, an oxide sintered body containing a constituent metal of a deposited film is generally used as a sputtering target of a raw material and generated in a vacuum. The argon ions are accelerated by an electric field and hit against a raw material (sputtering target) to repel the constituent atoms of the oxide sintered body as sputtering particles, and these sputtered particles are deposited on a substrate arranged in front of the sputtering target. Further, in the film formation (manufacturing) of the oxide film, oxygen gas may be added to the atmospheric gas.

When a Bi (V, W) O ₄ film is produced by a sputtering method, it is necessary to deposit it on a substrate heated to 500 ° C. or higher in order to obtain a crystal film. However, since the bismuth oxide component has a high vapor pressure as described above, the bismuth oxide component tends to volatilize from the deposited film in the vacuum during film formation, and the bismuth atom is missing from the chemical composition. Is manufactured, and it may be difficult to fully exhibit the photocatalytic performance.

In order to avoid this, it is effective to use an oxide sintered body containing an excess of bismuth component as a sputtering target. That is, in the case of producing a Bi (V, W) O ₄ film, even if bismuth continues to be excessively supplied to the heating substrate with respect to the total amount of vanadium and tungsten during sputtering film formation, the excess amount of bismuth is obtained from the substrate. Since it volatilizes, a Bi (V, W) O ₄ film can be produced.

The oxide sintered body according to the present invention contains bismuth, vanadium, tungsten, and oxygen, and the content of bismuth is 1.05 to 1.30 in terms of the number of bismuth / (vanadium + tungsten) atoms. Tungsten content is 0.01 to 0.05 in terms of tungsten / (vanadium + tungsten) atomic number ratio, and it is characterized by containing a crystal phase having a sinter-type crystal structure and a crystal phase having an auribilias-type crystal structure. do.

When the content of bismuth is less than 1.05 in the bismuth / (vanadium + tungsten) atomic number ratio, there is an adverse effect that a deposited film lacking bismuth atoms is formed as in the sputtering technique described in Patent Document 1. On the other hand, when the bismuth content exceeds 1.30 in the bismuth / (vanadium + tungsten) atomic number ratio, a second phase such as _{Bi 4} V ₂ O ₁₁ or Bi ₄ (V, W) ₂ O _{11 is generated.} This makes it easier to obtain a single-phase Bi (V, W) O ₄ film, which has an adverse effect. Further, when the tungsten content exceeds 0.05 in the tungsten / (vanadium + tungsten) atomic number ratio, there is an adverse effect that the photocatalytic characteristics of the produced coating film are deteriorated.

It is important that the oxide sintered body of the present invention is composed of a crystal phase having a sealite type crystal structure and a crystal phase having an auribilias type crystal structure. Here, examples of the crystal phase having a Scheelite-type crystal structure include a BiVO ₄ crystal phase or a Bi (V, W) O ₄ crystal phase, and a crystal having an Aulivillius-type crystal structure. Examples of the phase include a Bi ₄ V ₂ O ₁₁ crystal phase or a Bi ₄ (V, W) ₂ O ₁₁ crystal phase. The BiVO ₄ crystal phase and the Bi ₄ (V, W) ₂ O ₁₁ crystal phase may be tetragonal, monoclinic, or a mixture thereof.

Then, in the oxide sintered body of the present invention, the BiVO ₄ crystal phase or Bi (V, W) O ₄ crystal phase having a sealite type crystal structure is combined with the Bi ₄ V ₂ O ₁₁ crystal phase or Bi having an auribilias type crystal structure. _{By adopting a structure in which 4} (V, W) ₂ O ₁₁ crystal phases are mixed, the Bi content of the entire oxide sintered body can be excessive with respect _{to the Bi (V, W) O 4 film.} can.

Further, when the oxide sintered body according to the present invention contains a bismuth oxide phase, since the bismuth oxide component has a high vapor pressure as described above, the oxide sintered body is formed by plasma under vacuum during film formation. Since the bismuth oxide component easily volatilizes when heated, the composition of the oxide sintered body (target) changes, and a Bi (V, W) O ₄ film having a constant composition cannot be obtained. On the other hand, the auribilias type Bi ₄ V ₂ O ₁₁ crystal phase and the Bi ₄ (V, W) ₂ O ₁₁ crystal phase are formed because Bi ions are occupied as one of the lattices in the composite compound. Since the thermal stability is good even when heated by plasma in a vacuum at times, it is possible to maintain the composition of the oxide sintered body. Further, it is important that the oxide sintered body is formed in a form in which the particles of these crystal phases are uniformly mixed. By forming the oxide sintered body in such a phase configuration, even if it is used for sputtering film formation for a long time, the decrease in bismuth on the surface of the sintered body due to plasma heating can be suppressed to a small extent, so that the film is to be formed. Sputtered particles having a constant composition can be deposited on the substrate.

Here, the crystal phase of the Scheelite-type crystal structure and the crystal phase of the Aulivillius-type crystal structure constituting the oxide sintered body of the present invention have a complete chemical quantitative composition. No need. For example, the BiVO ₄ crystal phase, the Bi ₄ V ₂ O ₁₁ crystal phase, the Bi (V, W) O ₄ crystal phase, and the Bi ₄ (V, W) ₂ O ₁₁ crystal phase do not have to have a complete stoichiometric composition. good. That is, the atomic number ratio of bismuth / vanadium and the atomic number ratio of bismuth / (vanadium + tungsten) may deviate from the chemical quantity theory ratio, and oxygen deficiency may be included. It is preferable that oxygen deficiency is contained in order to obtain stable sputtering film formation with good conductivity due to such composition deviation.

By the way, although the oxide sintered body according to the present invention contains an auribilias type Bi ₄ (V, W) ₂ O ₁₁ crystal phase, the deposited film produced by the sputtering method is Bi (V, V, W) to become O ₄ film is due to the following reasons.

That is, the particles that are repelled from the oxide sintered body (target) by sputtering are oxidized even if the crystal phases constituting the target are Bi (V, W) O ₄ and Bi ₄ (V, W) ₂ O _11. This is because the atoms constituting the product sintered body (target) are Bi, V, W, and O, and these atoms reach the substrate arranged in front of the target to re-form a predetermined compound, and oxidation occurs. _{A Bi (V, W) O 4} film can be obtained by maintaining the bismuth / (vanadium + tungsten) atomic number ratio and the tungsten / (vanadium + tungsten) atomic number ratio of the material sintered body.

The oxide sintered body according to the present invention most preferably does not contain a bismuth oxide phase, but even if it contains a bismuth oxide phase, there is no problem as long as its particle size is less than 1 μm. When the bismuth oxide phase is contained, the particle size of the bismuth oxide phase is preferably 500 nm or less, more preferably 100 nm or less. When the bismuth oxide phase is contained in the oxide sintered body and the particle size of the bismuth oxide phase is 1 μm or more, the vapor pressure of the bismuth oxide is high, so that the surface of the oxide sintered body is exposed to plasma. When heated, bismuth oxide sublimates from the oxide sintered body in a short time, and it becomes impossible to maintain an appropriate excess state of bismuth in the oxide sintered body. Similarly, the oxide sintered body according to the present invention most preferably does not contain a tungsten oxide phase, but even if it contains a tungsten oxide phase, there is no problem as long as its particle size is less than 1 μm. When the tungsten oxide phase is contained, the particle size of the tungsten oxide phase is preferably 500 nm or less, more preferably 100 nm or less. When the tungsten oxide phase is contained in the oxide sintered body and the particle size of the tungsten oxide phase is 1 μm or more, the vapor pressure of tungsten oxide is also high, so that the surface of the oxide sintered body is exposed to plasma. When heated, tungsten oxide sublimates from the oxide sintered body in a short time, which causes a change in the composition of the oxide sintered body and the film to be formed. Further, in the oxide sintered body according to the present invention, since the particle size of the bismuth oxide phase or the tungsten oxide phase existing at the triple point is less than 1 μm, there is a problem even if the bismuth oxide phase or the tungsten oxide phase is present. There is no. Usually, such a phase is insignificant and is often amorphous.

(3) Method for Producing Oxide Sintered Body In order to produce the oxide sintered body according to the present invention, a bismuth raw material powder, a vanadium raw material powder and a tungsten raw material powder are mixed and crushed, and then granulated and obtained. It can be obtained by pressure-molding the granulated powder and firing the obtained molded product in the air.

Then, an oxide powder such as _{Bi 2} O _{3 and a carbonate compound powder such as (BiO) 2} CO ₃ can be used as the bismuth raw material powder, and _{an oxide powder such as V 2} O ₅ can be used as the vanadium raw material powder. It can be used, and an oxide powder such as _{WO 3} powder can be used as the tungsten raw material powder.

Further, these raw material powders preferably have an average particle size of 1 μm or less. When the particle size of the raw material powder exceeds 1 μm, the obtained oxide sintered body may contain a bismuth oxide phase or a tungsten oxide phase having a particle size of 1 μm or more. When a bismuth oxide phase having a particle size of 1 μm or more is contained, the vapor pressure of bismuth oxide is high. Therefore, when the surface of the oxide sintered body is heated by plasma during sputtering, the oxide sintered body is oxidized in a short time. Bismuth sublimates, making it difficult to maintain an excess state of bismuth in the oxide sintered body, and as a result, a Bi (V, W) O ₄ film having a constant composition cannot be stably produced. Further, when the tungsten oxide phase having a particle size of 1 μm or more is contained, the vapor pressure of tungsten oxide is also high, so that when the surface of the oxide sintered body is heated by plasma during sputtering, the oxide sintered body is released for a short time. In this case, tungsten oxide is sublimated and W cannot be taken into the film, and as a result, a Bi (V, W) O ₄ film having a constant composition cannot be stably produced.

Next, the mixing and crushing conditions for obtaining the granulated powder can be appropriately determined while paying attention to the particle size of the granulated powder. Further, as the equipment for obtaining the granulated powder, a known mixing and stirring device such as a ball mill, a bead mill, or an attritor can be used.

Further, in the pressure molding of the granulated powder, a die, a rubber or the like is filled with the granulated powder, and the granulated powder can be molded by a uniaxial press or a cold hydrostatic press.

Then, the obtained molded body is fired in the air at a temperature of 700 ° C. or higher to produce the oxide sintered body according to the present invention. The atmosphere at the time of firing may be an atmosphere in which oxygen is added to the atmosphere.

In the obtained oxide sintered body, the crystal phase contained in the oxide sintered body can be identified by X-ray diffraction measurement. The firing temperature, firing time, firing atmosphere, and temperature lowering rate can be appropriately selected so that a desired crystal phase can be obtained.

(4) Sputtering target In order to process the obtained oxide sintered body to produce a sputtering target, the oxide sintered body is cut to a size suitable for the sputtering cathode to be used, and the cut oxidation is performed. The sputtering surface (the surface on which erosion is formed) of the material sintered body is polished with a grindstone. Then, a sputtering target can be manufactured by bonding the polished oxide sintered body to a backing plate made of copper or the like using metallic indium or the like.

Hereinafter, examples of the present invention will be specifically described with reference to comparative examples.

[Example 1]
(Manufacturing of oxide sintered body)
Bi ₂ O ₃ powder with an average particle size of 1 μm or less, V ₂ O ₅ powder with an average particle size of 1 μm or less, and WO ₃ powder with an average particle size of 1 μm or less are used as raw material powders, and the content of bismuth is bismuth / The (vanadium + tungsten) atomic number ratio is 1.05, and the tungsten content is tungsten / (vanadium + tungsten) atomic number ratio of 0.01 [hereinafter, bismuth / (vanadium + tungsten) atomic number ratio and tungsten / (Vanadium + tungsten) The atomic number ratio is called "preparation composition at the time of producing the sintered body"], and the above Bi ₂ O ₃ powder, V ₂ O ₅ powder and WO ₃ powder are mixed and made of resin. It was placed in a pot and mixed with a wet ball mill. At this time, a hard ZrO ₂ ball was used and the mixing time was set to 18 hours.

Next, after mixing, the slurry was taken out, filtered, dried, and granulated, and the obtained granulated powder was molded by applying a pressure ^{of 3 ton / cm 2 with a cold hydrostatic press.}

Then, the obtained molded product was fired as follows.

The above-mentioned molded body was fired at 900 ° C. for 3 hours in an atmosphere in which oxygen was introduced into the atmosphere in the firing furnace at a ratio of 5 liters / minute per 0.1 m ^{3 of the furnace volume to produce an oxide sintered body.} At this time, the temperature was raised at 1 ° C./min, the introduction of oxygen was stopped during cooling after firing, and the temperature was lowered to 700 ° C. at 10 ° C./min.

(Analysis of oxide sintered body)
The broken material of the obtained oxide sintered body was crushed and the following analysis was carried out.

First, when the composition of the oxide sintered body was analyzed by ICP emission spectroscopy, it was confirmed that an oxide sintered body having the same composition as the above-mentioned charged composition was obtained.

Moreover, when the X-ray diffraction (XRD) measurement of the oxide sintered body was carried out, only the diffraction peaks caused by the crystal phase of the seerite type crystal structure and the crystal phase of the auribilias type crystal structure were observed, and the bismuth oxide crystal phase was observed. Was not observed.

Next, as microstructure analysis of the oxide sintered body, analysis was performed by a scanning electron microscope (SEM) equipped with an energy dispersive fluorescent X-ray analyzer (EDX), a transmission electron microscope (TEM), and electron diffraction. As a result, it was found that the crystal phases constituting the oxide sintered body were the Bi (V, W) O ₄ crystal phase and the Bi ₄ (V, W) ₂ O ₁₁ crystal phase. Moreover, in the microstructure analysis, the triple point of the oxide sintered body and the bismuth oxide phase which is amorphous at the grain boundary were not confirmed.

The results of these are shown in Table 1 below.

(Manufacturing of sputtering target)
Next, the obtained oxide sintered body was cut into a size of 152 mm in diameter and 5 mm in thickness, and the sputtering surface (the surface on which erosion was formed) of the cut oxide sintered body was cut with a cup grindstone. After polishing, the polished oxide sintered body was bonded to a backing plate made of oxygen-free copper using metallic indium.

Then, two sputtering targets having the same composition were produced by the above procedure and used for each analysis of the following "erosion portion composition" and "sedimentary film composition".

(Sputtering film formation test)
The film formation test using two sputtering targets was carried out individually according to the following procedure.

First, the sputtering target was attached to the cathode for a non-magnetic target in a vacuum chamber in a DC magnetron sputtering apparatus.

Further, this DC magnetron sputtering apparatus is equipped with a substrate holder with a heating function at a position 70 mm above the center of the target, and a quartz glass substrate having a thickness of 1 mm and a thickness of 50 mm × 50 mm is attached to the substrate holder.

Next, the vacuum chamber was evacuated to 10 × 10 ^-4 Pa or less, and then Ar gas having a purity of 99.9999% by weight and O ₂ gas were introduced at a ratio of 1% with respect to Ar gas to increase the gas pressure. The gas flow rate and the vacuum exhaust speed were controlled so as to be 0.5 Pa.

Then, after heating the quartz glass substrate to 600 ° C., a direct current of 300 W is applied between the target and the substrate to generate a direct current plasma, and a sputtering film formation is carried out until a 1200 nm deposited film is obtained on the quartz glass substrate. bottom.

According to the above procedure, using two sputtering targets having the same composition, the deposition film composition on the quartz glass substrate at each time point when the integrated input power to the targets is "0.15 kWh" and "10.0 kWh" [the above "deposit film composition" That is, the Bi / (V + W) atom number ratio and the W / (V + W) atom number ratio] and the sintered body composition of the erosion portion in the sputtering target (the above-mentioned "erosion part composition", that is, the Bi / (V + W) atom number ratio). ) Was measured by ICP emission spectroscopy.

The results of these are shown in Table 1.

(Measurement result)
The composition of the deposited film formed on the quartz glass substrate had a Bi / (V + W) atomic number ratio close to 1.0 in both "0.15 kWh" and "10.0 kWh". In the erosion portion of the sputtering target, the Bi / (V + W) atomic number ratio does not change significantly even when the integrated input power is “10.0 kWh”. This is because the sputtering target was prepared from an oxide sintered body composed of a Bi (V, W) O ₄ crystal phase in which _{V sites were replaced by W and a Bi 4} (V, W) ₂ O _{11 crystal phase.} Is.

Further, as a result of analyzing the crystal structure of the deposited film formed on the quartz glass substrate by X-ray diffraction (XRD) measurement, Bi (Bi ( V _0.99 W _0.01 ) O ₄ film was obtained in the form of a single phase. From this, when the film formation is performed using the sputtering target produced by using the oxide sintered body according to Example 1, Bi (Bi (stoichiometric composition) close to the stoichiometric composition even when continuously used for a long time. V _0.99 W _0.01 ) O ₄ film can be stably produced.

[Example 2]
(Manufacturing of oxide sintered body)
At a ratio of Bi / (V + W) atomic number ratio of 1.20 and W / (V + W) atomic number ratio of 0.04 (see "Preparation composition at the time of preparing sintered body" in Table 1), Bi ₂ O An oxide sintered body was produced in the same procedure as in Example 1 except that ₃ powder, V ₂ O ₅ powder and WO _{3 powder were mixed.}

(Analysis of oxide sintered body)
When the obtained fractured material of the oxide sintered body according to Example 2 was crushed and the same analysis as in Example 1 was carried out, it was confirmed that a sintered body having the same elemental composition as the charged composition was obtained. bottom.

Further, when the X-ray diffraction (XRD) measurement of the oxide sintered body according to Example 2 was carried out, the Bi (V, W) O ₄ crystal phase and the Bi ₄ (V, W) ₂ O ₁₁ crystal phase were obtained. Only the resulting diffraction peak was observed, not the bismuth oxide crystal phase.

Furthermore, when the microstructure analysis of the oxide sintered body was carried out, the presence of an amorphous bismuth oxide phase (particle size of about 20 nm) at the triple points and grain boundaries of the oxide sintered body was finely determined by SEM-EDX. It was confirmed by structural observation and local composition analysis.

(Sputtering film formation test)
Similar to Example 1, two sputtering targets having the same composition were used, and the deposition film composition on the quartz glass substrate at each time point when the integrated input power to the targets was "0.15 kWh" and "10.0 kWh" [the above "deposition""Filmcomposition", that is, Bi / (V + W) atom number ratio and W / (V + W) atom number ratio], and the sintered body composition of the erosion portion in the sputtering target (the above-mentioned "erosion portion composition", that is, Bi / (V + W) atom number. (Number ratio) was measured by ICP emission spectroscopy. These results are also shown in Table 1.

(Measurement result)
The composition of the deposited film formed on the quartz glass substrate had a Bi / (V + W) atomic number ratio close to 1.0 in both "0.15 kWh" and "10.0 kWh".

Further, in the erosion portion of the sputtering target, the Bi / (V + W) atomic number ratio does not change significantly even when the integrated input power is “10.0 kWh”. This is because the sputtering target was prepared from an oxide sintered body composed of a Bi (V, W) O ₄ crystal phase in which _{V sites were replaced by W and a Bi 4} (V, W) ₂ O _{11 crystal phase.} Is.

Further, as a result of analyzing the crystal structure of the deposited film formed on the quartz glass substrate by X-ray diffraction (XRD) measurement, Bi (V, W) was obtained in both "0.15 kWh" and "10.0 kWh". O ₄ film were obtained in the form of a single phase.

From the above, when a film is formed using the sputtering target produced by using the oxide sintered body according to Example 2, even if it is used continuously for a long time, Bi has a stoichiometric composition. (V, W) O ₄ film can be stably produced.

[Comparative Example 1]
(Manufacturing and analysis of oxide sintered body)
An oxide sintered body was produced by the same procedure as in Example 1 except that a powder having an average particle size of 15 μm was used as a Bi ₂ O _{3 raw material and the ball mill mixing time was set to 2 hours.}

When the obtained broken material of the oxide sintered body according to Comparative Example 1 was crushed and the same analysis as in Example 1 was carried out, the atomic number ratio of the same element composition [Bi / (V + W) as the charged composition was 1 A sintered body having an atomic number ratio of 0.05 and W / (V + W) of 0.01] was obtained.

However, according to X-ray diffraction (XRD) measurement, Bi (V, W) O 4 in addition to have the diffraction peaks attributed to Bi ₂ O ₃ crystalline phase is observed in the crystalline phase, Bi (V, W) O 4 It was found that the oxide sintered body was composed of a crystal phase and a Bi ₂ O _{3 crystal phase.} A similar microstructure analysis by SEM-EDX was also performed, and it was confirmed that the particles were composed of _{Bi (V, W) O 4} crystal phase particles and about 1 μm Bi ₂ O _{3 crystal particles.}

(Sputtering film formation test)
When a sputtering target was prepared from this oxide sintered body by the same procedure as in Example 1 and a deposited film was formed on a quartz glass substrate under the same procedure and conditions as in Example 1, "0.15 kWh" was formed. At the time of "10.0 kWh", the Bi (V, W) O ₄ film was obtained in the form of a single phase, but at the time of "10.0 kWh", the V ₂ O ₅ film was formed as the second phase, and the Bi (V) O 5 film was formed. , W) No single-phase film of _{O 4 was obtained.} Table 1 shows the composition analysis results of the sedimentary film and the erosion portion at "0.15 kWh" and "10.0 kWh".

At "0.15 kWh", the state of excess Bi was maintained, but as the integrated input power was increased, the amount of Bi in the erosion portion decreased sharply, and at "10.0 kWh", the composition of excess Bi was not obtained. rice field.

For this reason, excess Bi cannot be supplied to the substrate, and the Bi (V, W) O ₄ film is not stably formed in the form of a single phase, and the second phase of the _{V 2} O _{5 film is formed.} It is presumed that it was done.

If Bi ₂ O ₃ phase in the target was present, when it is heated by the plasma in a vacuum Bi ₂ O ₃ crystalline phase is likely to be lost by evaporation, erosion unit Bi (V, W) O ₄ crystalline phase only It is presumed that it has changed.

From such an oxide sintered body, it is not possible to manufacture a sputtering target that can be continuously used in mass production.

According to the sputtering target according to the present invention, a Bi (V, W) O ₄ film having a stoichiometric composition in which bismuth atoms are not deleted can be continuously produced. Therefore, it has industrial applicability used in the production of Bi (V, W) O _{4 films used for photocatalysts.}

Claims (5)

It contains bismuth, vanadium, tungsten, and oxygen, and the content of bismuth is 1.05-1.30 in the ratio of bismuth / (vanadium + tungsten) atoms, and the content of tungsten is tungsten / (vanadium + tungsten) atoms. An oxide sintered body having a numerical ratio of 0.01 to 0.05 and containing a crystal phase having a sealite type crystal structure and a crystal phase having an auribilias type crystal structure. The oxide sintered body according to claim 1, wherein the bismuth oxide phase is not contained, or even if the bismuth oxide phase is contained, the particle size is less than 1 μm. The oxide sintered body according to claim 1 or 2, wherein the tungsten oxide phase is not contained, or the particle size is less than 1 μm even if the tungsten oxide phase is contained. The bismuth raw material powder, the vanadium raw material powder, and the tungsten raw material powder are mixed, crushed, and granulated, the obtained granulated powder is pressure-molded, and the obtained molded body is fired to claim 1-3. In the method for producing the oxide sintered body according to any one of the above.
A method for producing an oxide sintered body, wherein the average particle size of the bismuth raw material powder, the vanadium raw material powder, and the tungsten raw material powder is 1 μm or less. A sputtering target obtained by processing the oxide sintered body according to any one of claims 1 to 3.