JP2015013778A - Oxidation sinter body and production method thereof, and oxidation film - Google Patents

Abstract

An In—Si—O-based oxide sintered body is provided that can perform stable discharge, which is impossible with conventional techniques.
A main phase is a crystal phase of an indium silicate compound that includes In and Si, the Si content is 0.65 or more and 1.75 or less in terms of the number ratio of Si / In, and has a tortobitite structure. And an oxide sintered body containing no silicon dioxide phase and no metallic silicon phase.
[Selection figure] None

Description

  The present invention relates to an oxide sintered body mainly composed of an oxide containing indium and silicon, a method for producing the same, and an oxide film obtained using the oxide sintered body.

  Oxide films are used in a wide variety of applications, including solar cells, liquid crystal display elements, other light receiving element electrodes, various heat-reflective films for automobiles and buildings, antistatic films, and transparent anti-fogging elements for refrigeration showcases. Has been used for a long time. Further, it is also applied as an optical film typified by an antireflection film, a reflection increasing film, an interference film, a polarizing film and the like. As an optical film, the application as a laminated body which combined the oxide film which has various characteristics is made | formed.

  The spectral characteristic of the oxide multilayer film is determined by the refractive index “n” and the film thickness “d” of each layer when the extinction coefficient k can be regarded as almost zero. Therefore, in the optical design of a laminate using an oxide film, it is generally performed by calculation based on the data “n” and “d” of each layer constituting the multilayer film. In this case, in addition to combining a high refractive index film and a low refractive index film, a film having an intermediate refractive index (intermediate refractive index film) is further added to provide superior optical characteristics. A multilayer film is obtained.

Generally, as a high refractive index film (n> 1.90), TiO ₂ (n = 2.4), CeO ₂ (n = 2.3), ZrO ₂ (n = 2.2), Nb ₂ O ₅ (N = 2.1), Ta ₂ O ₅ (n = 2.1), WO ₃ (n = 2.0) and the like are known. As the low refractive index film (n <1.60), SiO ₂ (n = 1.4), MgF ₂ (n = 1.4), and the like are known. In addition, as the intermediate refractive index film (n = 1.60 to 1.90), Al ₂ O ₃ (n = 1.6), MgO (n = 1.7), Y ₂ O ₃ (n = 1. 8) etc. are known.

  As a method for forming these various oxide films, a sputtering method, a vapor deposition method, an ion plating method, and a solution coating method are generally used. Among them, the sputtering method is an effective method when film formation of a material having a low vapor pressure or precise film thickness control is required, and the operation is very simple, and thus is widely used industrially. .

  Specifically, in the sputtering method, a target is used as a raw material. In this method, generally, under a gas pressure of about 10 Pa or less, a substrate is used as an anode, a target is used as a cathode, and glow discharge is generated between these anode and cathode to generate argon plasma. Then, an argon cation in the plasma is collided with a target of the cathode, and particles of a target component that is blown off by this are deposited on the substrate to form a film.

  This sputtering method is classified according to the method of generating argon plasma. A method using high frequency plasma is called a high frequency sputtering method, and a method using direct current plasma is called a direct current sputtering method. In general, the direct current sputtering method is widely used industrially for reasons such as a higher film forming speed than a high frequency sputtering, a cheap power supply facility, and a simple film forming operation. For example, direct current magnetron sputtering is widely used in the production of transparent conductive thin films. However, generally, in the sputtering method, when the target of the raw material is an insulating target, it is necessary to use high-frequency sputtering, and this method makes it impossible to obtain a high film formation rate.

On the other hand, general intermediate refractive index materials such as Al ₂ O ₃ , MgO, and Y ₂ O ₃ described above are poor in conductivity, and stable discharge cannot be realized even if they are used as they are as sputtering targets. Therefore, in order to obtain an intermediate refractive index film by the sputtering method, sputtering (reactive sputtering method) is performed while reacting metal particles and oxygen in an oxygen-rich atmosphere using a conductive metal target. is necessary. However, in the reactive sputtering method containing a large amount of oxygen, the film formation rate is extremely slow, and thus productivity is significantly impaired. As a result, there are industrial problems such as an increase in the unit price of the obtained intermediate refractive index film.

  Here, an In—Si—O-based oxide sintered body has been proposed as a material for obtaining an intermediate refractive index film (see Patent Document 1). In general, an In—Si—O-based sintered body containing high concentration Si is poor in sinterability and conductivity. Therefore, in the technique described in Patent Document 1, in order to solve these problems, a sintered body is obtained by using indium oxide powder and silicon powder as raw materials and using a hot press method.

  However, in this method, since Si powder which is a non-oxide is used as a raw material, as a result, the Si phase remains in the sintered body. Therefore, when a film is formed by sputtering using this sintered body as a target, oxygen contained in the chamber causes an oxidation reaction of Si that generates very high heat of oxidation combustion on the target surface, and the target surface state becomes extremely rough. As a result, film formation sometimes cannot be continued.

  In addition, as a technique for obtaining a highly conductive In—Si—O-based oxide sintered body, for example, Patent Document 2 proposes an indium oxide-based low-resistance target to which Si and Sn are added. However, the composition of this target is not an intermediate refractive index composition because the Si content is as low as 0.26 or less in terms of Si / In atomic ratio.

Patent Document 3 proposes an indium oxide-based low resistance target to which Si and Sn are added. In the technique of Patent Document 3, an indium silicate compound In ₂ Si ₂ O ₇ phase having a tortveitite structure is formed by high-temperature sintering at 1400 ° C. or higher in order to maintain stability during film formation. % Is deposited at a rate of at least%. However, even in this target, the Si content is small as in Patent Document 2, specifically, SiO ₂ is ₂ to 8 wt%, and the Si / In atomic ratio is small. Therefore, when a high concentration of Si is required, if the deposited phase is about 40%, a large amount of SiO ₂ phase that is an insulating phase remains, and stable film formation cannot be achieved.

On the other hand, regarding a sintered body containing high-concentration Si, Patent Document 4 proposes a composition in which SnO ₂ and TiO ₂ are added, and CIP molding is performed at a pressure of 160 MPa and sintered at 1400 to 1600 ° C. A sintered body is obtained. However, this sintered body is specialized for lowering the resistance. When SiO ₂ has a high concentration of 7 to 40 wt%, SnO ₂ is SnO ₂ / (In ₂ O ₃ + SnO ₂ ) = 0.10. It is necessary to add until it becomes. When the amount of SnO _{2 and the} amount of TiO ₂ having a refractive index of 2.0 or more is large, the refractive index becomes high, so that the target intermediate refractive index film cannot be obtained. In addition, since impurities other than In and Si become excessive, the proportion of In ₂ Si ₂ O ₇ phase decreases, and arcing due to unstable compound phases occurs when used for continuous film formation. Therefore, stable discharge is difficult. Further, in the production, there is no description regarding the particle size of the raw material powder, and the relative density of the sintered body is not mentioned at all, and a sufficiently stable film formation cannot be realized.

  As described above, there is no useful sputtering target for realizing stable film formation using a sputtering method in an indium oxide-based material containing a high concentration of Si.

Japanese Patent No. 4915065 Japanese Patent No. 4424889 JP 2007-176706 A Japanese Patent No. 4028269

  Therefore, the present invention has been made in view of the above-described circumstances, and in an In—Si—O-based oxide sintered body, oxide sintering that enables stable discharge, which was impossible with the prior art. It is an object of the present invention to provide an oxide film having an intermediate refractive index obtained by using the oxide body and its oxide sintered body.

  In order to achieve the above-mentioned object, the present invention has the following features. That is, the oxide sintered body according to the present invention includes In and Si, the Si content is 0.65 or more and 1.75 or less in terms of the number ratio of Si / In, and has a tortite structure. The crystal phase of the indium silicate compound is a main phase, and the silicon dioxide phase and the metal silicon phase are not included.

  The oxide sintered body according to the present invention has a relative density of 70% or more with respect to the density calculated from the abundance ratio and the true density of each compound phase constituting the oxide sintered body.

  Further, in the oxide sintered body according to the present invention, the ratio of the indium silicate compound crystal having a dortite structure is 70% by mass or more.

The method for producing an oxide sintered body according to the present invention is a method for producing an oxide sintered body having the characteristics described above, and is an indium silicate compound having a SiO ₂ powder or a tortovite structure as a Si raw material. The powder is used, the average particle size of the raw material powder is pulverized to 1.0 μm or less using a bead mill, and the raw material powder is molded at a pressure of 98 to 300 MPa by a cold isostatic pressing method to obtain a molded body. In a sintering furnace using zirconia as a furnace material in a portion in contact with the body, the sintered body is sintered by a normal pressure sintering method at a sintering temperature of 1400 to 1600 ° C. to obtain an oxide sintered body. It is characterized by obtaining.

  The oxide film according to the present invention is an oxide film obtained by a sputtering method using the oxide sintered body having the above-described characteristics as a sputtering target, and has a refractive index of 1.70 to 1.90. It is characterized by being.

  According to the oxide sintered body according to the present invention, a target for preparing an oxide film capable of stable discharge can be manufactured by a sputtering method. Then, an optically useful intermediate refractive index film can be stably formed by sputtering using this oxide sintered body as a sputtering target.

Hereinafter, specific embodiments to which the present invention is applied (hereinafter referred to as “the present embodiment”) will be described in detail in the following order.
1. Oxide sintered body 2. Manufacturing method of oxide sintered body Oxide film 4. Example

[1. Oxide sintered body]
The oxide sintered body according to the present embodiment is an oxide sintered body containing indium (In) and silicon (Si). Specifically, this oxide sintered body contains indium oxide as a main component and contains Si, and the Si content is 0.65 to 1.75 in terms of Si / In atomic ratio, The main phase is a crystal phase of an indium silicate compound having a biteite structure, and it does not contain a silicon dioxide phase and a metal silicon phase.

  In forming an oxide film using an oxide sintered body as a sputtering target, in the stabilization of discharge in the sputtering, not only the density of the sintered body, but also the main phase of the compound phase constituting the sintered body, It has been found that the content of silicon (Si) (composition of the sintered body) also depends significantly.

  Therefore, in the oxide sintered body according to the present embodiment, indium oxide is the main component and silicon oxide or the like is added. The silicon content is 0.65 in terms of the Si / In atomic ratio. This is 1.75 or less.

  If the Si / In atomic ratio is less than 0.65, the oxide film obtained using the oxide sintered body has a high refractive index, while the Si / In atomic ratio exceeds 1.75. Since the refractive index of the oxide film is lowered, an oxide film having a desired intermediate refractive index cannot be obtained.

Further, in order to stabilize the discharge of the sintered body in sputtering, the oxide sintered body needs to have a relative density of 70% or more, but the silicon content is 0.6 mol with respect to 1 mol of indium. If it exceeds the vicinity, the sinterability is significantly reduced. Therefore, especially when SiO ₂ is used as a starting material, sintering at normal atmospheric pressure becomes extremely difficult. Therefore, in the present embodiment, as will be described in detail later, CIP (cold isostatic pressing) molding is performed at a pressure of 98 to 300 MPa with the average particle size of the raw material powder being 1.0 μm or less, and contact with the molded body. In a sintering furnace using zirconia as the furnace material of the portion to be processed, an oxide sintered body is obtained by performing normal pressure sintering at a sintering temperature of 1400 to 1600 ° C. Thereby, an oxide sintered body having a high relative density of 70% or more can be obtained.

  Here, in calculating the relative density of the oxide sintered body, since the true density varies greatly depending on the compound present in the sintered body, the definition of the true density is important. That is, the relative density with respect to the density calculated from the abundance ratio and true density of each compound phase constituting oxide sintering must be calculated.

For example, in an indium oxide-based sintered body containing SiO ₂ at a ratio of 30% by mass, indium oxide (7.18 g / cm ³ ) and silicon dioxide (2.32 g / cm ³ ) are present alone. Is calculated with a true density of 4.41 g / cm ³ , but since the true density of the indium silicate compound phase, which is the main phase, is actually 6.34 g / cm ³ , the abundance ratio of this indium silicate compound phase is also If a true density is not taken into account, a large difference from the original relative density will occur. Therefore, in the present embodiment, the relative density with respect to the density calculated from the abundance ratio and the true density of each compound phase is adopted.

  Now, in order to stabilize the discharge of the sintered compact in sputtering, as mentioned above, the compound phase which comprises the oxide sintered compact also has big influence. The oxide sintered body according to the present embodiment is composed of an indium silicate compound crystal phase of a tortveitite type structure as a main phase. In particular, it is preferable that the ratio of the indium silicate compound crystal having a dortite structure is 70% by mass or more.

  Thus, according to the oxide sintered body in which the indium silicate compound crystal having the tortobitite structure is the main phase, and preferably the proportion of the compound phase is 70% by mass or more, Si is taken into the indium silicate compound crystal. Therefore, the silicon dioxide phase is not formed, and the occurrence of arcing that effectively inhibits continuous discharge can be suppressed. Therefore, the oxide sintered body according to the present embodiment does not include a silicon dioxide phase.

  In addition, the indium silicate compound having a tortuitite structure is a compound described in JCPDS card 31-600, Journal of Solid State Chemistry 2,199-202 (1970), and there is a slight compositional deviation from the stoichiometric composition. It does not matter as long as it is maintained as long as this crystal structure is maintained.

  In the oxide sintered body according to the present embodiment, there is no metal silicon phase. More specifically, this oxide sintered body is obtained by, for example, measuring a generated phase by X-ray diffraction using CuKα rays on a sintered powder obtained by pulverization, or processing the oxide sintered body by FIB or the like. The above-described silicon dioxide phase and metal silicon phase are not detected even by the generated phase measurement by electron beam diffraction on the thin piece obtained in this manner.

  By setting it as the oxide sintered compact which does not have such a metal silicon phase, it becomes a target which can perform sputtering, without raise | generating the rough surface of the target which was the subject conventionally. The reason for this can be explained as follows. That is, the mechanism of film formation in sputtering is that argon ions in the plasma collide with the target surface to repel target component particles and deposit them on the substrate. At this time, when a film is formed using an oxide sintered body having a Si precipitate phase as a target, oxygen supplied from the sintered body or oxygen contained when oxygen gas containing oxygen is introduced. Then, Si in the sintered body causes an oxidation reaction by plasma heating. It has been found that this oxidation reaction generates very high oxidation combustion heat of 930 kJ / mol, and causes remarkable roughness of the target surface due to local heat generation. On the other hand, by using an oxide sintered body composed of a high proportion of indium silicate compound and having no Si precipitation phase as a target, it is possible to avoid abnormal situations such as significant roughening or arcing of the target surface, and stable discharge. Is possible.

  As described above, the oxide sintered body according to the present embodiment has a tortobitite-type structure in the composition region where the sinterability is not necessarily high and the Si / In atomic ratio is 0.65 to 1.75. It is an oxide sintered body having a crystal phase of an indium silicate compound having a main phase and a high relative density. For such an oxide sintered body, as will be described later, the average particle diameter of the raw material powder is 1.0 μm or less, CIP molding is performed at a pressure of 98 to 300 MPa, and the furnace material in a part in contact with the molded body is used. It can be obtained by performing normal pressure sintering at 1400 to 1600 ° C. in a sintering furnace using zirconia. Even if any of these conditions is missing, an oxide sintered body having the above-described characteristics cannot be obtained.

[2. Manufacturing method of oxide sintered body]
Next, the manufacturing method of the oxide sintered compact mentioned above is demonstrated.

  The method for producing an oxide sintered body according to the present embodiment is a method for obtaining a granulated powder by mixing raw material powder with pure water, an organic binder, and a dispersant, and drying and granulating the resulting slurry. 1 process, the 2nd process which press-molds the obtained granulated powder, and obtains a molded object, and the 3rd process of baking the obtained molded object at normal pressure and obtaining a sintered compact. As described above, the manufacturing method according to the present embodiment is characterized in that an oxide sintered body is obtained by sintering by the atmospheric pressure sintering method, which is a sintering method by the atmospheric pressure sintering method. However, as described above, an oxide sintered body capable of stable discharge during sputtering can be obtained.

<First step (granulation step)>
The first step is a granulation step of preparing a granulated powder by blending raw material powders of components constituting the oxide sintered body at a predetermined ratio. More specifically, in this first step, each raw material powder is prepared at a predetermined ratio and mixed with, for example, pure water, an organic binder, and a dispersing agent to obtain a slurry, and the obtained slurry is dried to prepare. Granulated powder is obtained by granulating.

  In the method for manufacturing an oxide sintered body according to the present embodiment, indium oxide powder is used as the In raw material, and silicon dioxide powder is used as the Si raw material, respectively. Moreover, you may use the indium silicate compound powder which has a tortovite type structure as needed. The indium silicate compound powder can be prepared by mixing indium oxide powder and silicon dioxide powder, calcining, and pulverizing. As the average particle size of each raw material powder, if the particle size is too large, the relative density of the oxide sintered body is lowered and the strength and conductivity of the sintered body are also lowered. Preferably there is.

  Thus, in this method of manufacturing an oxide sintered body, without using non-oxide silicon powder (metal silicon) as a raw material, silicon dioxide powder or indium silicate compound powder having a tortovite type structure is used. Use. Thereby, an oxide sintered compact can be manufactured stably and the sintered compact in which Si precipitation phase does not exist can be obtained. When silicon powder is used, there is a risk of abnormal sintering due to local heat generation due to oxidation of Si during atmospheric pressure sintering in the atmosphere or oxygen atmosphere, making it difficult to produce a stable sintered body. Further, even if an oxide sintered body is obtained, the Si precipitate phase remains, and there is a possibility that the target surface will be significantly roughened during the sputtering film formation.

  As described above, these raw material powders are weighed and mixed at a ratio such that silicon is 0.65 to 1.75 in terms of the Si / In atomic ratio.

  Next, each raw material powder weighed in a predetermined amount is mixed with pure water, an organic binder, and a dispersant, and mixed so that the raw material powder concentration is 50 to 80% by mass, preferably 60% by mass, To do. And it wet-grinds so that the mixed powder in a slurry may become a predetermined | prescribed average particle diameter.

  It grind | pulverizes until it becomes 1.0 micrometer or less as an average particle diameter of the mixed powder (raw material powder) obtained by wet grinding. When the average particle size of the raw material powder exceeds 1.0 μm, not only the relative density of the sintered body is reduced, but also the contact area between the particles is reduced, so that the generation of a tortuitite-type indium silicate compound phase is suppressed. As a result, sintering may be hindered, and as a result, an oxide sintered body having sufficient density and conductivity for stable discharge may not be obtained.

In this wet pulverization, for example, it is preferable to use a bead mill into which hard balls (ZrO ₂ balls or the like) having a particle size of 2.0 mm or less are charged. Thereby, aggregation of each raw material powder can be reliably removed. In addition, in a ball mill using a ball having a particle diameter exceeding 2.0 mm, it becomes difficult to crush the particles to a particle diameter of 1.0 μm or less, resulting in insufficient sintering. The conductivity is insufficient.

  In this first step, the slurry obtained by mixing the raw material powder as described above is wet pulverized, and then, for example, the slurry obtained by stirring for 30 minutes or more is dried and granulated. Get granulated powder.

<Second step (molding step)>
The second step is a molding step in which the granulated powder obtained in the first step described above is pressure-molded to obtain a molded body.

In this second step, pressure molding is performed at a pressure of 98 MPa (1.0 ton / cm ² ) to 300 MPa (3.06 ton / cm ² ) in order to remove voids between the particles of the granulated powder. In this pressure molding, it is preferable to use a cold isostatic press (CIP) method capable of applying a high pressure.

  When the molding pressure is less than 98 MPa, the contact between the particles becomes insufficient, and therefore the proportion of the tortuitite-type indium silicate compound phase becomes less than 70% by mass when the molded body is sintered at normal pressure. End up. On the other hand, even if the molding pressure is higher than 300 MPa, the effect of increasing the contact between the particles is small, and the ratio of the indium silicate compound phase having the tortovite type structure cannot be increased. Moreover, since the apparatus for setting the molding pressure exceeding 300 MPa is very expensive, when the molding pressure exceeds 300 MPa, the production cost increases and it becomes economically very inefficient.

<Third step (firing step)>
The third step is a firing step for obtaining an oxide sintered body by firing the molded body obtained in the second step described above at normal pressure.

In the firing process in the third step, a sintering furnace using zirconia is used as a furnace material in a portion that comes into contact with the compact to be sintered, and the maximum firing temperature is 1400 ° C. or higher and 1600 ° C. or lower, preferably 1450 ° C. Normal pressure sintering is performed at a sintering temperature of 1550 ° C. or lower. When the sintering temperature is less than 1400 ° C., not only necessary sintering shrinkage is not obtained, but also the proportion of the tortobitite-type In ₂ Si ₂ O ₇ phase which is an indium silicate compound phase is less than 70% by mass. As a sputtering target, it becomes an unstable compound phase. On the other hand, when the firing temperature exceeds 1600 ° C., it is preferable because not only power consumption and production efficiency are lowered, but also the sintered body may be deformed by a eutectic reaction between SiO ₂ and ZrO _2. Absent.

Here, in the manufacturing method according to the present embodiment, a member such as a floor plate in contact with the molded body is sintered using a sintering furnace made of zirconia. For example, when alumina is used for the flooring material, the sintered body is deformed by eutectic reaction between SiO ₂ and Al ₂ O ₃ in the molded body. When the Si / In atomic ratio is smaller than 0.65, even if a eutectic reaction occurs, the reaction amount is small so that the sintered body is not deformed, but the Si / In atomic ratio exceeds 0.65. And when a calcination temperature exceeds 1400 degreeC, it will deform | transform remarkably. At this time, the eutectic reaction between the SiO ₂ and the compound constituting the furnace material is performed by sintering under a temperature condition of 1400 ° C. or higher and 1600 ° C. or lower in a sintering furnace using zirconia as a member in contact with the molded body. Suppressing and preventing the sintered body from deforming can be obtained, and a high-density oxide sintered body having a relative density of 70% or more with the crystal phase of the indium silicate compound as the main phase can be obtained. .

As described above, the method for manufacturing an oxide sintered body according to the present embodiment uses an SiO ₂ powder or an indium silicate compound powder having a tortovite type structure as an Si raw material, and an average particle size of 1.0 μm or less. The raw material powder was subjected to CIP molding at a pressure of 98 to 300 MPa, and the resulting molded body was sintered at normal pressure at a temperature of 1400 to 1600 ° C. in a sintering furnace using zirconia as the furnace material. As a result, the characteristic oxide sintered body described above can be obtained.

  And, for the obtained oxide sintered body, it is made a desired target shape by performing circumferential processing and surface grinding, and by bonding the processed oxide sintered body to the backing plate, It can be set as a sputtering target.

  According to the sputtering target thus formed, during sputtering, it is possible to prevent the occurrence of arcing due to an unstable compound phase, and to stably discharge, and an optically extremely useful intermediate refractive index. A film can be formed stably.

[3. Oxide film]
The oxide film according to this embodiment can be formed by using an oxide sintered body having the above-described characteristics as a sputtering target and forming a film over a substrate such as glass by a sputtering method.

  As described above, this oxide film is composed of indium oxide as a main component and added with Si, and the Si content is 0.65 to 1.75 in terms of the Si / In atomic ratio, The oxide phase of the indium silicate compound having a bitite-type structure is the main phase, and the oxide sintered body that does not contain the silicon dioxide phase and the metal silicon phase is used as a raw material. The oxide film reflects the composition. Therefore, this oxide film is an intermediate refractive index film made of an oxide containing indium and silicon and having a refractive index of 1.70 to 1.90.

  The thickness of the oxide film is not particularly limited, and can be set as appropriate depending on the film formation time, the type of sputtering method, and the like. Specifically, for example, the thickness is about 5 to 300 nm.

  Here, in the sputtering, the sputtering method is not particularly limited, and a DC (direct current) sputtering method, an AC (alternating current) sputtering method, an RF (high frequency) magnetron sputtering method, an electron beam evaporation method, an ion plating method. Law. Among these, it is preferable to perform sputtering by a direct current sputtering method.

  As the substrate, for example, glass, resin (PET, PES, or the like) can be used.

  The temperature at which the oxide film is formed by sputtering is not particularly limited, but is preferably 50 ° C. or higher and 300 ° C. or lower, for example. If the deposition temperature is less than 50 ° C., the oxide film obtained by condensation may contain moisture. On the other hand, when the film formation temperature exceeds 300 ° C., the substrate may be deformed, or stress may remain in the obtained oxide film and may be cracked.

Although it does not specifically limit as a pressure in the chamber at the time of sputtering, For example, it is preferable to evacuate to about 5 * 10 < ^-5 > Pa, for example. The power output input during sputtering is usually 10 to 1000 W, preferably 100 to 300 W when a sputtering target having a diameter of 152.4 mm (6 inches) is used.

Examples of the carrier gas at the time of sputtering include gases such as oxygen, helium, argon, xenon, and krypton, and a mixed gas of argon and oxygen is preferably used. When using a mixed gas of argon and oxygen, the flow ratio of argon and oxygen is usually Ar: O ₂ = 100 to 80: 0 to 20, preferably 100 to 90: 0 to 10.

[4. Example]
Examples of the present invention will be specifically described below in comparison with comparative examples. In addition, this invention is not limited by this Example.

Example 1
<Preparation of sintered oxide>
In ₂ O ₃ powder having an average particle size of 1.0 μm or less and SiO ₂ powder are used as raw material powders, and the Si / In atomic ratio is adjusted to 1.0, so that the raw material powder concentration is 60% by mass. Were mixed with pure water, an organic binder and a dispersant, and a slurry was prepared in a mixing tank.

Next, using a bead mill apparatus (manufactured by Ashizawa Finetech Co., Ltd., LMZ type) into which hard ZrO ₂ balls having a particle diameter of 0.5 mm are introduced, the particle diameter (median diameter) of the raw material powder is 0.7 μm. Wet grinding was performed until Then, the slurry obtained by mixing and stirring for 30 minutes or more was sprayed and dried with a spray dryer (Okawara Chemical Industries, Ltd., ODL-20 type) to obtain “granulated powder”. A laser diffraction particle size distribution measuring device (SALD-2200, manufactured by Shimadzu Corporation) was used to measure the average particle size of the raw material powder.

Next, the obtained granulated powder was molded by applying a pressure of 294 MPa (3.0 ton / cm ² ) with a cold isostatic press, and the obtained molded body of about 200 mmφ was obtained in an atmospheric pressure firing furnace. An oxide sintered body was obtained by firing at a maximum firing temperature of 1500 ° C. for 20 hours. The floor plate of the firing furnace was made of zirconia. No significant deformation was observed in the obtained oxide sintered body.

Here, the milled end material of the obtained oxide sintered body was pulverized, and the product phase was identified by powder X-ray diffraction measurement using CuKα rays. As a result, In ₂ Si ₂ O having a tortovite type structure was obtained. Only the _7- phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. A slight peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 98% by mass, and the rest was In ₂ O _{There were three} phases.

Further, the end material of the obtained oxide sintered body was sliced by FIB processing and observed with a transmission electron microscope (TEM) mounted on an energy dispersive X-ray fluorescence spectrometer (EDX). As a result, it was confirmed from the electron beam diffraction that the oxide sintered body had no SiO ₂ phase or Si phase alone.

Next, when the density of the obtained oxide sintered body was measured by the Archimedes method, it was 4.8 g / cm ³ . As described above, 6.34 g / cm ³ which is the density of In ₂ Si ₂ O ₇ crystal having a tortuitite structure and 7.18 g / cm ³ which is the density of In ₂ O ₃ crystal having a bixbite structure. When the relative density with respect to the density of 6.35 g / cm ³ calculated from the abundance ratio of each phase was calculated, it was 76%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the oxide sintered body obtained in Example 1 was processed to have a diameter of 152.4 mm (6 inches) and a thickness of 5 mm, and metal indium was applied to the backing plate made of oxygen-free copper. Bonding was performed to obtain a sputtering target.

  Next, using the obtained sputtering target, a film was formed by direct current sputtering. A sputtering target obtained was attached to a cathode for a non-magnetic target of a DC magnetron sputtering apparatus (manufactured by Tokki, SPF-530K). On the other hand, an alkali-free glass substrate (Corning # 7059, thickness) (T): 1.1 mm), the target-substrate distance was fixed to 60 mm.

Then, after evacuating to 5 × 10 ⁻⁵ Pa or less, pure Ar gas and pure Ar + O ₂ gas are introduced so that the O ₂ concentration becomes 1.0%, and the gas pressure is set to 0.6 Pa. 200 W was applied to generate DC plasma, and pre-sputtering was performed.

  After sufficient pre-sputtering, the substrate was placed immediately above the center (non-erosion portion) of the sputtering target, and sputtering was performed without heating to form an oxide film having a thickness of 200 nm.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Moreover, it was 1.8 when the refractive index of the obtained oxide film was measured with the ellipsometer.

  Thus, it was confirmed that the oxide sintered body obtained in Example 1 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

<< Example 2 >>
<Preparation of sintered oxide>
The granulated powder of Example 1 was put in a zirconia mortar and calcined at a temperature of 1400 ° C. for 20 hours in an atmospheric firing furnace. As a result of XRD Rietveld analysis of the calcined powder obtained by this calcining, 98% by mass was an indium silicate compound having a tortuitite structure, and the rest was indium oxide. An oxide sintered body was produced in the same manner as in Example 1 except that this calcined powder was used as a raw material powder and that the median diameter of the raw material powder after wet pulverization by a bead mill apparatus was set to 0.9 μm. No significant deformation was observed in the obtained oxide sintered body. Subsequently, in the same manner as in Example 1, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase and the Si phase, and the relative density of the oxide sintered body were measured.

As a result of identification of the generated phase by powder X-ray diffraction measurement on the end material of the obtained oxide sintered body, the oxide sintered body of Example 2 also has In ₂ which has a tortobitite type structure. Only the Si ₂ O ₇ phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. A peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 99% by mass, which was higher than 70% by mass A proportion of In ₂ Si ₂ O ₇ phase was present and the remainder was In ₂ O ₃ phase.

Moreover, when the thin piece of the obtained oxide sintered compact was observed with TEM equipped with EDX, it was confirmed from the electron beam diffraction that the SiO ₂ phase and the Si phase were not present alone.

Moreover, it was 5.6 g / cm < ³ > when the density of the obtained oxide sintered compact was measured by the Archimedes method. When the relative density with respect to the density of 6.35 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 88%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Further, when the refractive index of the obtained oxide film was examined, it was 1.8.

  Thus, it was confirmed that the oxide sintered body obtained in Example 2 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

Example 3
<Preparation of sintered oxide>
As a raw material powder, a mixed powder prepared by mixing the In ₂ O ₃ powder and the SiO ₂ powder of the raw material powder used in Example 1 at a ratio that the Si / In atomic ratio is 1.0, and used in Example 2 Example 1 with the exception of using a calcined powder mainly composed of an indium silicate compound having a tortuitite-type structure and using a raw powder obtained by mixing a mixed powder and a calcined powder in a ratio of 1: 1. An oxide sintered body was produced in the same manner. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

As a result of identification of the generated phase by powder X-ray diffraction measurement on the end material of the obtained oxide sintered body, the oxide sintered body of Example 3 also has In ₂ which has a tortobitite type structure. Only the Si ₂ O ₇ phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. The peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 98% by mass, which was higher than 70% by mass A proportion of In ₂ Si ₂ O ₇ phase was present and the remainder was In ₂ O ₃ phase.

Moreover, when the thin piece of the obtained oxide sintered compact was observed with TEM equipped with EDX, it was confirmed from the electron beam diffraction that the SiO ₂ phase and the Si phase were not present alone.

Moreover, it was 5.2 g / cm ³ when the density of the obtained oxide sintered compact was measured by the Archimedes method. When the relative density with respect to the density of 6.35 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 82%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Further, when the refractive index of the obtained oxide film was examined, it was 1.8.

  Thus, it was confirmed that the oxide sintered body obtained in Example 3 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

Example 4
<Preparation of sintered oxide>
An oxide sintered body was produced in the same manner as in Example 1 except that the pressure at which the compact was molded was 100 MPa. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

It was subjected to identification of the product phase by powder X-ray diffraction measurement with respect to the end parts of the obtained oxide sintered body, in the oxide sintered body of Example 4, an In ₂ is Toruto by tight structure Only the Si ₂ O ₇ phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. The peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 98% by mass, which was higher than 70% by mass A proportion of In ₂ Si ₂ O ₇ phase was present and the remainder was In ₂ O ₃ phase.

Moreover, when the thin piece of the obtained oxide sintered compact was observed with TEM equipped with EDX, it was confirmed from the electron beam diffraction that the SiO ₂ phase and the Si phase were not present alone.

Further, the density of the obtained oxide sintered body was measured by Archimedes method and found to be 4.6 g / cm ³ . When the relative density with respect to the density of 6.35 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 72%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Further, when the refractive index of the obtained oxide film was examined, it was 1.8.

  Thus, it was confirmed that the oxide sintered body obtained in Example 4 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

Example 5
<Preparation of sintered oxide>
An oxide sintered body was produced in the same manner as in Example 1 except that the sintering temperature was 1400 ° C. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

As a result of identification of the generated phase by powder X-ray diffraction measurement on the end material of the obtained oxide sintered body, the oxide sintered body of Example 5 also has In ₂ which has a tortobitite type structure. Only the Si ₂ O ₇ phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. A peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 72% by mass, which was higher than 70% by mass A proportion of In ₂ Si ₂ O ₇ phase was present and the remainder was In ₂ O ₃ phase.

Moreover, when the thin piece of the obtained oxide sintered compact was observed with TEM equipped with EDX, it was confirmed from the electron beam diffraction that the SiO ₂ phase and the Si phase were not present alone.

Moreover, it was 4.7 g / cm < ³ > when the density of the obtained oxide sintered compact was measured by the Archimedes method. When the relative density with respect to the density of 6.55 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 72%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Further, when the refractive index of the obtained oxide film was examined, it was 1.8.

  Thus, it was confirmed that the oxide sintered body obtained in Example 5 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

Example 6
<Preparation of sintered oxide>
An oxide sintered body was produced in the same manner as in Example 1 except that the sintering temperature was 1600 ° C. There was no significant deformation in the oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

It was subjected to identification of the product phase by powder X-ray diffraction measurement with respect to the end parts of the obtained oxide sintered body, in the oxide sintered body of Example 6, an In ₂ is Toruto by tight structure Only the Si ₂ O ₇ phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. A peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 99% by mass, which was higher than 70% by mass A proportion of In ₂ Si ₂ O ₇ phase was present and the remainder was In ₂ O ₃ phase.

Moreover, when the thin piece of the obtained oxide sintered compact was observed with TEM equipped with EDX, it was confirmed from the electron beam diffraction that the SiO ₂ phase and the Si phase were not present alone.

Moreover, it was 5.2 g / cm ³ when the density of the obtained oxide sintered compact was measured by the Archimedes method. When the relative density with respect to the density of 6.35 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 82%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Further, when the refractive index of the obtained oxide film was examined, it was 1.8.

  Thus, it was confirmed that the oxide sintered body obtained in Example 6 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

Example 7
<Preparation of sintered oxide>
The oxide firing was carried out in the same manner as in Example 1 except that the Si / In atomic ratio of the raw material powder was 0.65 and that the median diameter of the raw material powder after wet pulverization with a bead mill was 0.4 μm. A ligature was prepared. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

It was subjected to identification of the product phase by powder X-ray diffraction measurement with respect to the end parts of the obtained oxide sintered body, in the oxide sintered body of Example 7, an In ₂ is Toruto by tight structure Only the Si ₂ O ₇ phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. A peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 72% by mass, which was higher than 70% by mass A proportion of In ₂ Si ₂ O ₇ phase was present and the remainder was In ₂ O ₃ phase.

Moreover, when the thin piece of the obtained oxide sintered body was observed with a TEM equipped with EDX, the oxide sintered body of Example 7 also had a single SiO ₂ phase and Si phase from electron diffraction. Not confirmed.

Moreover, it was 4.7 g / cm < ³ > when the density of the obtained oxide sintered compact was measured by the Archimedes method. When the relative density with respect to the density of 6.55 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 72%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Further, when the refractive index of the obtained oxide film was examined, it was 1.9.

  Thus, it was confirmed that the oxide sintered body obtained in Example 7 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

Example 8
<Preparation of sintered oxide>
An oxide sintered body was produced in the same manner as in Example 1 except that the Si / In atomic ratio of the raw material powder was 1.75. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

It was subjected to identification of the product phase by powder X-ray diffraction measurement with respect to the end parts of the obtained oxide sintered body, in the oxide sintered body of Example 8, an In ₂ is Toruto by tight structure Only the Si ₂ O ₇ phase peak was detected, and the SiO ₂ and Si phase peaks were not detected. The peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 98% by mass, which was higher than 70% by mass A proportion of In ₂ Si ₂ O ₇ phase was present and the remainder was In ₂ O ₃ phase.

Moreover, when the thin piece of the obtained oxide sintered body was observed with a TEM equipped with EDX, the oxide sintered body of Example 8 also had a single SiO ₂ phase and Si phase from electron diffraction. Not confirmed.

Moreover, it was 4.5 g / cm < ³ > when the density of the obtained oxide sintered compact was measured by the Archimedes method. When the relative density with respect to the density of 6.35 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 71%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, no crack was generated in the sputtering target, and no significant roughening of the target surface, abnormal discharge, or the like occurred in 10 minutes from the initial stage of film formation. Further, when the refractive index of the obtained oxide film was examined, it was 1.7.

  Thus, it was confirmed that the oxide sintered body obtained in Example 8 is useful as a sputtering target for stably obtaining an intermediate refractive index film.

≪Comparative example 1≫
<Preparation of sintered oxide>
Using In ₂ O ₃ powder having an average particle diameter of 5.0 μm and SiO ₂ powder as raw material powder, in wet grinding of the raw material powder, using a ball mill apparatus with hard ZrO ₂ balls having a particle diameter of 2.0 mm, An oxide sintered body was produced in the same manner as in Example 1 except that the median diameter of the raw material powder was 1.2 μm. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

When the formed phase of the obtained oxide sintered body was identified by powder X-ray diffraction measurement, the peak of the In ₂ Si ₂ O ₇ phase, which is a tortovite type structure, was detected. As a result of analyzing the weight ratio of the compound phase by Rothveld analysis, the ratio of the In ₂ Si ₂ O ₇ phase was extremely low at 64% by mass, and the remainder was 25% by mass of the In ₂ O ₃ phase and 11% of the SiO ₂ phase. %Met.

Observation of the obtained oxide-sintered thin piece with a TEM equipped with EDX confirmed from electron beam diffraction that the Si phase did not exist alone but the SiO ₂ phase existed.

When the density of the obtained oxide sintered body was measured by the Archimedes method, it was 3.7 g / cm ³ . When the relative density with respect to the density of 5.46 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 68%, which was a low density lower than 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, although the target surface was not significantly roughened in 10 minutes from the initial stage of film formation, an abnormal discharge occurred and the oxide film could not be stably formed and the refractive index could be evaluated. Was not obtained.

«Comparative example 2»
<Preparation of sintered oxide>
An oxide sintered body was produced in the same manner as in Example 1 except that the pressure during molding of the molded body was 50 MPa. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

When the formed phase of the obtained oxide sintered body was identified by powder X-ray diffraction measurement, the peak of the In ₂ Si ₂ O ₇ phase, which is a tortovite type structure, was detected. As a result of analyzing the weight ratio of the compound phase by Rietveld analysis, the ratio of the In ₂ Si ₂ O ₇ phase was as extremely low as 50% by mass, and the remainder was 35% by mass of the In ₂ O ₃ phase and 15% of the SiO ₂ phase. %Met.

Observation of the obtained oxide-sintered thin piece with a TEM equipped with EDX confirmed from electron beam diffraction that the Si phase did not exist alone but the SiO ₂ phase existed.

When the density of the obtained oxide sintered body was measured by the Archimedes method, it was 3.1 g / cm ³ . When the relative density with respect to the density of 5.20 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 60%, which was a low density lower than 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, although the target surface was not significantly roughened in 10 minutes from the initial stage of film formation, an abnormal discharge occurred and the oxide film could not be stably formed and the refractive index could be evaluated. Was not obtained.

«Comparative Example 3»
<Preparation of sintered oxide>
An oxide sintered body was produced in the same manner as in Example 1 except that the sintering temperature was 1300 ° C. No significant deformation was observed in the obtained oxide sintered body. Subsequently, the existence ratio of the In ₂ Si ₂ O ₇ phase, the presence or absence of the SiO ₂ phase, the Si phase, and the relative density of the oxide sintered body were measured.

When the formed phase of the obtained oxide sintered body was identified by powder X-ray diffraction measurement, the peak of the In ₂ Si ₂ O ₇ phase, which is a tortovite type structure, was detected. As a result of analyzing the weight ratio of the compound phase by Rietveld analysis, the ratio of the In ₂ Si ₂ O ₇ phase was as extremely low as 10% by mass, and the remainder was 63% by mass of the In ₂ O ₃ phase and 27% of the SiO ₂ phase. %Met.

Observation of the obtained oxide-sintered thin piece with a TEM equipped with EDX confirmed from electron beam diffraction that the Si phase did not exist alone but the SiO ₂ phase existed.

When the density of the obtained oxide sintered body was measured by the Archimedes method, it was 2.9 g / cm ³ . When the relative density with respect to the density of 4.55 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 64%, which was a low density lower than 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. And the oxide film was formed using the sputtering target.

  As a result, although the target surface was not significantly roughened in 10 minutes from the initial stage of film formation, an abnormal discharge occurred and the oxide film could not be stably formed and the refractive index could be evaluated. Was not obtained.

<< Comparative Example 4 >>
<Preparation of sintered oxide>
As a raw material powder, an In ₂ O ₃ powder having an average particle diameter of 1.0 μm or less and a metal silicon powder having an average particle diameter of 5 μm are mixed in a three-dimensional mixer, and the obtained mixed powder is placed in a carbon container. Powdered, and hot-pressed under the conditions of a sintering temperature of 950 ° C. and a pressure of 4.9 MPa to produce an oxide sintered body, and the presence ratio of In ₂ Si ₂ O ₇ phase, presence or absence of SiO ₂ phase, Si phase The relative density was measured.

When the generated phase was identified by powder X-ray diffraction measurement for the end material of the obtained oxide sintered body, only the peak of the In ₂ Si ₂ O ₇ phase, which is a tortovite type structure, was detected, The peaks of SiO ₂ phase and Si phase were not detected. The peak of In ₂ O ₃ phase was also detected, but when the weight ratio of the compound phase was analyzed by Rietveld analysis, the ratio of In ₂ Si ₂ O ₇ phase was 97% by mass, and the rest was In ₂ O ₃ It was a phase.

However, when the obtained oxide-sintered thin piece was observed with a TEM equipped with EDX, it was confirmed from electron diffraction that the Si 2 phase was present although the SiO ₂ phase was not present alone.

It was 5.8 g / cm < ³ > when the density of the obtained oxide sintered compact was measured by the Archimedes method. When the relative density with respect to the density of 6.36 g / cm ³ calculated from the abundance ratio of each phase described above was calculated, it was 91%, which was a high density exceeding 70%.

<Production of oxide film>
Subsequently, the obtained oxide sintered body was processed in the same manner as in Example 1, and bonded to a backing plate made of oxygen-free copper using metal indium to produce a sputtering target. Then, an attempt was made to form an oxide film using the sputtering target.

  However, since the target surface was significantly roughened immediately after the start of film formation and abnormal discharge occurred frequently, the film formation was stopped.

<< Comparative Example 5 >>
<Preparation of sintered oxide>
An oxide sintered body was produced in the same manner as in Example 1 except that the bottom plate of the atmospheric firing furnace was made of alumina.

  As a result, the obtained oxide sintered body has been significantly deformed and cannot be used as a sputtering target. Evaluation of the oxide sintered body and oxides targeted by the oxide sintered body The film formation was not evaluated.

  In the following Table 1, the manufacturing conditions of the sintered bodies in Examples 1 to 8 and Comparative Examples 1 to 5, the constituent components (compound phase ratio) and density of the obtained oxide sintered bodies, and the oxide sintering The following is a summary of the presence / absence of surface roughness of the target, the presence / absence of abnormal discharge during film formation, and the refractive index of the oxide film when the film is formed by sputtering.

Claims (5)

  Silicon dioxide containing In and Si, having a Si content of 0.65 to 1.75 in terms of the Si / In atomic ratio, and having a crystal phase of an indium silicate compound having a tortovite structure as a main phase. An oxide sintered body comprising no phase and no metal silicon phase.   2. The oxide sintered body according to claim 1, wherein a relative density with respect to a density calculated from an abundance ratio and a true density of each compound phase constituting the oxide sintered body is 70% or more.   3. The oxide sintered body according to claim 1, wherein a ratio of the indium silicate compound crystal having a dortite structure is 70% by mass or more. A method for producing an oxide sintered body according to any one of claims 1 to 3,
Using an indium silicate compound powder having a SiO ₂ powder or a tortovite type structure as a Si raw material, using a bead mill, the average particle size of the raw material powder is pulverized to 1.0 μm or less,
Molding the raw material powder at a pressure of 98 to 300 MPa by a cold isostatic pressing method to obtain a molded body,
In a sintering furnace using zirconia as a furnace material in a portion in contact with the molded body, the molded body is sintered by a normal pressure sintering method at a sintering temperature of 1400 to 1600 ° C. to obtain an oxide sintered body. A method for producing an oxide sintered body characterized by: An oxide film obtained by a sputtering method using the oxide sintered body according to any one of claims 1 to 3 as a sputtering target,
An oxide film having a refractive index of 1.70 to 1.90.