JP2007290875A - Titanium oxide-based sintered compact and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering target suppressing the generation of abnormal electric discharge and the occurrence of cracks and breakage during sputtering in forming a titanium oxide-based thin film and a titanium oxide-based sintered compact to be used as its raw material. <P>SOLUTION: The titanium oxide-based sintered compact which contains a metal M consisting of at least one kind selected from elements in groups 5A and 6A of the periodic table at an atomic ratio M/(Ti+M) of 0.002-0.15, does not contain an oxide represented by M<SB>x</SB>O<SB>y</SB>, and has a relative density of ≥95%, a specific resistance of ≤50 Ω cm and an average crystal grain diameter of ≤5 μm is obtained by mixing and pulverizing raw material powder having a specific surface area of 1-15 m<SP>2</SP>/g, rapidly drying and granulating its slurry, and sintering the obtained granules at 800-1,200°C for 30 min-5 h under pressure of 9.8 MPa or above. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sputtering target used for forming a titanium oxide-based transparent thin film by a sputtering method, a titanium oxide-based sintered body used for the sputtering target, and a method for producing the same.

  Titanium oxide thin films exhibit a high refractive index and are widely used as optical thin films.

  In general, in optical design, a high refractive index film and a low refractive index film are used, and an optical thin film having excellent optical characteristics is realized by laminating these films. As materials for a high refractive index film having a refractive index greater than 2, titanium oxide, niobium oxide, tantalum oxide, cerium oxide, and the like are known. On the other hand, silicon oxide, magnesium fluoride and the like are known as materials for a low refractive index film having a refractive index smaller than 1.5.

  Examples of the method for forming the titanium oxide thin film include a coating method, a vapor deposition method, and a sputtering method. However, it is difficult for the coating method and the vapor deposition method to form a uniform film on a large area substrate such as building glass or automotive glass. For this reason, the method of forming a titanium oxide thin film using sputtering method is preferable on production.

  In the sputtering method, reactive sputtering in which a film is formed in an atmosphere containing oxygen using a metal titanium sputtering target is widely used. This is because a sputtering target made of titanium oxide has no electrical conductivity and cannot be used for direct current (DC) sputtering. However, in the reactive sputtering method, it is necessary to introduce oxygen gas of 10% or more in terms of argon ratio. When the amount of oxygen gas to be introduced is large, the film forming rate becomes extremely slow, so that the reactive sputtering method has a problem of lack of mass productivity.

  In order to enable direct current sputtering using a sputtering target made of titanium oxide, it has been reported that conductivity is imparted to a titanium oxide sintered body (Patent Documents 1 and 2). In such a titanium oxide sintered body, a titanium dioxide powder is hot-pressed in a non-oxidizing atmosphere to transfer oxygen from the powder to the atmosphere, thereby having a structure having oxygen defects, and having a specific resistance of 10 Ωcm or less. Have gained. However, such a sintered body has a problem that cracks and cracks occur during sputtering.

  In addition, in order to realize higher-speed film formation, a titanium oxide-based sintered body to which a metal oxide having a relatively high refractive index and a high film formation speed is added has been reported. However, in such a sintered body, since the oxide of the additive element is dispersed, there is a problem that abnormal discharge tends to occur during sputtering starting from the oxide (Patent Documents 1 to 3).

  If abnormal discharge frequently occurs during sputtering, the plasma discharge state becomes unstable, and stable film formation is not performed, which adversely affects film characteristics. In addition, when a crack or a crack occurs in the sputtering target during sputtering, a lower oxide called nodule may be generated at the generation site. Nodules cause abnormal discharge and decrease the deposition rate during sputtering. In addition, the generation of particles and adhesion to the thin film adversely affects film properties such as refractive index and transmittance.

JP-A-7-233469

Japanese Patent Laid-Open No. 2004-2202

JP 2001-58871 A

  An object of the present invention is to provide a sputtering target capable of suppressing the occurrence of abnormal discharge, cracks and cracks in sputtering in the formation of a titanium oxide thin film, and a titanium oxide sintered body as a raw material thereof. And

In the titanium oxide-based sintered body according to the present invention, a metal M mainly composed of titanium oxide and composed of at least one of group 5A elements and group 6A elements on the periodic table of elements has an M / (Ti + M) ratio of 0.00. wherein such a proportion of from 002 to 0.15, and there is no oxide represented by M _x O _y, the relative density of 95% or more, a specific resistance of 50Ωcm or less, the crystal grain size of 5μm or less It is characterized by being.

Such titanium oxide-based sintered body has a specific surface area of 1~15m ² / g, titanium oxide powder, Group on the Periodic Table of the Elements 5A element, a metal oxide powder of a metal M consisting of at least one Group 6A element or After mixing and pulverizing the raw material powder made of metal powder so that the atomic ratio of M / (Ti + M) was 0.002 to 0.15, the obtained slurry was rapidly dried and granulated. The granulated powder is produced by molding and sintering in a vacuum or in an inert gas atmosphere at 800 to 1200 ° C. for 30 minutes to 5 hours at a pressure of 9.8 MPa or more.

  The sputtering target according to the present invention is obtained by processing the obtained titanium oxide-based sintered body into a predetermined shape.

  In the sputtering target using the titanium oxide-based sintered body according to the present invention, cracks and cracks do not occur in direct current sputtering, and abnormal discharge is less likely to occur. Therefore, by using such a sputtering target, a high-quality transparent thin film can be formed efficiently, inexpensively and with energy saving.

In order to solve the above problems, the present inventor conducted an analysis on a titanium oxide-based sintered body, and as a result of intensive studies, in order to use the titanium oxide-based sintered body as a sputtering target,
(1) At least one of group 5A element and group 6A element in the periodic table is added,
(2) The density of the sintered body is 95% or more in terms of relative density,
(3) The specific resistance of the sintered body is 50 Ωcm or less,
(4) The average crystal grain size is 5 μm or less. (5) The phase structure is mainly composed of TiO ₂ and no oxide represented by M _x O _y is present.
The knowledge that is needed. These will be specifically described.

(Metal element)
In the case of a titanium oxide-based sintered body, if sintering is performed in an oxidizing atmosphere such as an oxygen atmosphere or an air atmosphere, insulation is exhibited, and film formation by an industrially preferable direct current sputtering method becomes impossible.

  Therefore, in order to obtain a conductive titanium oxide-based sintered body, it is necessary to introduce oxygen vacancies by sintering in a reducing atmosphere and to increase the carrier concentration by solid solution of pentavalent or higher metal elements. Even if only titanium oxide is sintered in a reducing atmosphere, a conductive sintered body can be obtained. However, by containing a metal element, a higher-strength sintered body can be obtained, and cracks during sputtering and Generation of cracks can be suppressed.

  In the titanium oxide-based sintered body according to the present invention, for the purpose of increasing the carrier concentration and increasing the strength of the sintered body, such metal elements are group 5A elements and group 6A elements on the periodic table. Specifically, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten.

  In the titanium oxide-based sintered body according to the present invention, a metal M composed of at least one of group 5A elements and group 6A elements on the periodic table of elements, a ratio of M / (Ti + M) in an atomic ratio of 0.002 to 0.15. To be included. When the atomic ratio is less than 0.002, the strength of the sintered body is lowered, and cracks tend to occur frequently. On the other hand, if it exceeds 0.15, not only does the specific resistance of the sintered body become higher than 50 Ωcm, but also the thermal expansion coefficient of the sintered body decreases, and during cooling after sintering, As a result, the difference in thermal expansion increases and sintering cracks occur.

(Sintered body density)
The sintered body density of the sintered body is preferably 95% or more in terms of relative density. When the density of the sintered body is less than 95%, the specific resistance of the sintered body increases and the generation of nodules also increases.

  Here, the relative density is calculated from the actual density of the sintered body actually produced by calculating the true density using Equation 1. In addition, the measured value of a sintered compact density is computed from mass and its dimension.

Calculated true density = 100 / ((TiO ₂ blending ratio (mass%) / TiO ₂ density) + (metal oxide blending ratio (mass%) / metal oxide density)) Formula 1
(Sintered body resistivity)
In the sputtering target, the specific resistance is important. When the specific resistance of the target is high, heat conduction is deteriorated, so that thermal stress is generated in the target, and cracks and cracks are likely to occur. For this reason, it is preferable that the specific resistance is small in the sintered compact used for a sputtering target.

  In addition, by using a sintered body having a small specific resistance as a sputtering target, the current and voltage during film formation are reduced, and a reduction in damage to the film and energy saving are also expected.

  Therefore, the specific resistance of the sintered body is preferably 50 Ωcm or less. The specific resistance of the sintered body is measured by a four-end needle method.

  In addition, the specific resistance of a sintered compact can be 50 ohm-cm or less by making the relative density of a sintered compact 95% or more.

(Average crystal grain size)
When the average crystal grain size in the sintered body is large, the strength of the sintered body is lowered. For this reason, when sputtering is performed using a sintered body having a large crystal grain size, the frequency of occurrence of cracks and cracks in the sputtering target increases. Further, when the crystal grain size is increased, not only the strength of the sintered body is lowered, but isolated vacancies are present in the grains, which causes crack starting points and low density. Therefore, a smaller crystal grain size is better.

  In order to suppress the generation of cracks and cracks due to a decrease in the strength of the sintered body and achieve a high density of the sintered body, the average crystal grain size is preferably 5 μm or less.

  The average crystal grain size is measured by SEM observation after the fracture surface of the sintered body is mirror-polished and then grain boundaries are precipitated by thermal corrosion.

(Phase structure)
If an additive metal oxide represented by M _x O _y such as niobium oxide, tantalum oxide, vanadium oxide, and molybdenum oxide is present in the sintered body in addition to the titanium oxide phase, it causes abnormal discharge in sputtering. Therefore, it is preferable that the additive metal oxide represented by M _x O _y does not exist in the sintered body. The presence of the added metal oxide is judged by X-ray diffraction.

  In the present invention, the absence of added metal oxide means that no heterogeneous peak is observed by X-ray diffraction. If the peak of the added metal oxide is not observed by X-ray diffraction, it is judged that the added metal oxide does not exist even if the added metal oxide is recognized by microscopic observation with an electron microscope or the like.

  By providing these conditions in the titanium oxide-based sintered body, it is possible to obtain a sputtering target with less generation of cracks and cracks and abnormal discharge over the long term.

  Next, the inventor examined each factor affecting the characteristics of the titanium oxide-based sintered body in the manufacturing process of the titanium oxide-based sintered body.

  The production process of a titanium oxide sintered body basically includes mixing titanium oxide powder and added metal oxide powder or raw material powder made of metal powder and granulating to obtain granulated powder. Thus, the granulated powder is molded and sintered to obtain a sintered body.

[Raw material powder]
In order to set the relative density of the sintered body to 95% or more, it is necessary to control the specific surface area of each raw material. When the specific surface area is too low, the particle size of the raw material is increased and the powder packing density is increased. However, since the particle size is large and the surface energy is small, the sintering driving force is reduced, and high density cannot be achieved. On the contrary, when the specific surface area is too high, the packing density of the raw material becomes low, and the voids generated there cause low density. Therefore, in any case, the density of the sintered body is not increased, and the strength of the sintered body is lowered, causing nodules.

Therefore, in order to obtain the titanium oxide-based sintered body of the present invention, a powder having a specific surface area of 1 to 15 m ² / g is used as the raw material titanium oxide powder, metal oxide powder or metal powder.

  Titanium oxide powder, and metal oxide powder or metal powder satisfying the above specific surface area, a metal M composed of one or a plurality of additional metals, and M / (Ti + M) is 0.002 in atomic ratio. Weigh and prepare to have a ratio of ˜0.15.

[Mixing and grinding]
The presence or absence of the added metal oxide in the sintered body is affected by the mixing and grinding conditions of the raw material powder and the granulation method. In the raw material powder mixing step, it is necessary to make the raw material particle size and additive distribution uniform.

  In the raw material powder mixing step, a wet or dry ball mill, vibration mill, bead mill, or the like can be used. In order to obtain uniform and fine crystal grains and vacancies, a bead mill mixing method is most preferable because the crushing efficiency of the aggregates is high in a short time and the additive is well dispersed.

  The pulverization and mixing time by the bead mill varies depending on the size of the apparatus and the amount of slurry to be processed, but the maximum particle size of the slurry is preferably 1 μm or less.

  If the treatment time is short, the raw material powder cannot be uniformly mixed and pulverized, so that the existing coarse particles may become an added metal oxide. On the other hand, if pulverization and mixing are performed for a long time, fine particles are present, the packing density of the raw material is lowered, and the relative density of the sintered body is lowered.

[Quick drying granulation]
In order to produce a sintered body in which no added metal oxide is present, a granulation method using rapid drying is required in the granulation step of obtaining granulated powder from the raw material powder slurry.

  That is, when the raw material powder is ball mill mixed and pulverized and then dried by natural drying, the settling speed varies depending on the difference in specific gravity of the raw material powder. It becomes impossible. When molding and sintering are performed using this non-uniform granulated powder, an additive metal oxide of about several tens to 100 μm is bent, which causes an abnormal discharge.

  As an apparatus for rapid drying granulation, a spray dryer is widely used. The specific drying conditions are determined by various conditions such as the slurry concentration of the slurry to be dried, the temperature of hot air used for drying, the air volume, etc., and therefore, it is necessary to obtain optimum conditions in advance.

[Sintering method]
As a sintering method for obtaining the titanium oxide-based sintered body of the present invention, in addition to the hot press method, sintering in a reducing atmosphere and pressure sintering with hot isostatic pressure can be employed.

  In the hot press method, in order to apply a large force to the pressing mold at a high temperature, it is possible to perform sintering by placing inclusions in part or all of the part where the carbon mold and the compact (sintered body) are in contact. it can. Thereby, it can prevent that a sintered compact and a carbon type adhere | attach firmly during sintering.

  As the material of the inclusion, any material can be used without particular limitation as long as it does not react or adhere to carbon during sintering and does not affect the sintered body. For example, iron foil, a carbon sheet, stainless steel foil, nickel foil, tantalum foil, etc. are mentioned.

[Sintering atmosphere]
An inert gas such as argon, helium, or xenon can be used as the hot press atmosphere in order to reduce the exhaustion of the graphite mold, but it is particularly preferably performed in a vacuum atmosphere of 10 Pa or less.

[Sintering temperature, time, pressure]
In order to obtain a sintered body having predetermined conditions for the sintered body density and the average crystal grain size, it is necessary to adjust the sintering conditions such as the sintering temperature, the sintering time, and the pressure during sintering.

  The sintering temperature is 800 to 1200 ° C. When the sintering temperature is less than 800 ° C., the relative density of the sintered body cannot be made 95% or more, the strength of the sintered body is lowered, and nodules are generated. On the other hand, when the sintering temperature exceeds 1200 ° C., significant crystal grain growth causes an increase in average crystal grain size and generation of coarse pores, resulting in a decrease in sintered body strength and abnormal discharge. In addition, a reaction occurs between the sintered body and the furnace, which is not preferable for production.

  The sintering time is in the range of 30 minutes to 5 hours. If it is less than 30 minutes, the average crystal grain size of the sintered body is 5 μm or less, but it is not sufficiently sintered, and the relative density of the sintered body is less than 95%. If the sintering time is 30 minutes or more, the relative density of the sintered body can be 95% or more. On the other hand, when the sintering time exceeds 5 hours, the relative density of the sintered body exceeds 95%, but the average crystal grain size of the sintered body increases and the sintered body strength decreases.

  The pressure during sintering is preferably 9.8 MPa or more. When the pressure is less than 9.8 MPa, the relative density of the sintered body is less than 95%. In particular, 20 MPa or more is preferable.

  By controlling the various conditions in the manufacturing process of the sintered body as described above, the relative density is 95% or more, the specific resistance is 50 Ω · cm or less, the average crystal grain size is 5 μm or less, and substantially In particular, a titanium oxide-based sintered body free from metal oxide can be obtained.

  By processing such a titanium oxide-based sintered body into a predetermined shape, a sputtering target that can be used for forming a titanium oxide-based transparent thin film and that is free from nodules, abnormal discharge, and cracks and cracks is obtained. be able to.

Hereinafter, the present invention will be described in detail by way of examples.

[Example 1]
Titanium oxide (TiO ₂ ) powder having a specific surface area of 7.3 m ² / g and niobium oxide (Nb ₂ O ₅ ) powder having a specific surface area of 8.5 m ² / g were converted to Nb / (Ti + Nb) = 0.06 in atomic ratio. The mixture was mixed and pulverized with a bead mill until the particle size of each raw material powder became 1 μm or less. The specific surface area was measured with a BET specific surface area measuring apparatus (manufactured by Mountec Co., Ltd., Macsorb HMmodel-1208).

The slurry thus produced was taken out and rapidly dried and granulated using a spray dryer under the conditions of a slurry supply rate of 140 ml / min, a hot air temperature of 140 ° C., and a hot air amount of 8 Nm ³ / min.

  The obtained granulated powder was filled in a graphite mold and sintered by hot pressing. The hot pressing was performed in a vacuum atmosphere at a sintering temperature of 950 ° C., a sintering time of 3 hours, a pressure of 30 MPa, and 10 MPa or less.

  After calculating the density of the obtained sintered body from the mass and geometric dimensions of the sintered body, a part of the sintered body is cut, the cut portion is mirror-polished, and then thermally corroded, thereby scanning electrons. The average crystal grain size was measured from SEM observation with a microscope (S-800, manufactured by Hitachi High-Technologies Corporation). Moreover, X-ray diffraction using an X-ray diffractometer (manufactured by Rigaku Corporation, rad-RVB) was performed. As a result, in the phase structure of this sintered body, the rutile type titanium oxide phase was the main phase, and no diffraction peak due to niobium oxide was detected.

  The obtained sintered body was processed into a disk shape having a diameter of 75 mm and a thickness of 6 mm to produce a sputtering target. Using this target, the number of abnormal discharges during DC magnetron sputtering and the presence or absence of cracks were examined. The sputtering conditions were fixed at an input power of 200 W and an Ar gas pressure of 0.3 Pa. And the frequency | count of abnormal discharge which generate | occur | produces per 10 minutes after 10-hour progress from the experiment start was measured.

  The obtained measurement results are shown in Table 1. In addition, when the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was measured, 2.5 and a high value were shown.

[Example 2]
In the same manner as in Example 1, except that titanium oxide (TiO ₂ ) powder having a specific surface area of 1.3 m ² / g and niobium oxide (Nb ₂ O ₅ ) powder having a specific surface area of 10.1 m ² / g were used. A bonded body and a sputtering target were prepared.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the phase structure of this sintered body was mainly composed of rutile titanium oxide, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Example 3]
In the same manner as in Example 1, except that titanium oxide (TiO ₂ ) powder having a specific surface area of 14.8 m ² / g and niobium oxide (Nb ₂ O ₅ ) powder having a specific surface area of 10.3 m ² / g were used. A bonded body and a sputtering target were prepared.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the phase structure of this sintered body was mainly composed of rutile titanium oxide, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. The refractive index at a wavelength of 550 nm of the film obtained by the film formation was 2.5.

[Example 4]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the sintering temperature was 800 ° C. and the sintering time was 30 minutes.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. The refractive index at a wavelength of 550 nm of the film obtained by the film formation was 2.5.

[Example 5]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the sintering temperature was 1200 ° C. and the sintering time was 5 hours.

  Measurements and tests were performed in the same manner as in Example 1. From the result of X-ray diffraction of the obtained sintered body, the phase structure of this sintered body was a rutile type titanium oxide phase as a main phase, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Example 6]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the pressure during sintering was 9.8 MPa.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index of the film | membrane in wavelength 550nm of the film | membrane obtained by film-forming was 2.5.

[Example 7]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the atomic ratio of niobium as an additive metal was 0.002.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Example 8]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the atomic ratio of niobium as an additive metal was 0.15.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. The refractive index at a wavelength of 550 nm of the film obtained by the film formation was 2.5.

[Example 9]
Titanium oxide (TiO ₂ ) powder having a specific surface area of 7.3 m ² / g and tungsten oxide (WO ₃ ) powder having a specific surface area of 10.1 m ² / g are set to have an atomic ratio of W / (Ti + W) = 0.06. A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the mixture was mixed and pulverized until the particle size of each raw material powder became 1 μm or less using a bead mill.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to tungsten oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Comparative Example 1]
Except for using titanium oxide (TiO ₂ ) powder with a specific surface area of 0.5 m ² / g and niobium oxide (Nb ₂ O ₅ ) powder with a specific surface area of 0.9 m ² / g, A sintered body and a sputtering target were prepared.

  Measurements and tests were performed in the same manner as in Example 1. When the particle size distribution of the obtained slurry was measured, the maximum particle size of the slurry was 10 μm. Further, in the X-ray diffraction of the obtained sintered body, a diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. The refractive index at a wavelength of 550 nm of the film obtained by the film formation was 2.5.

[Comparative Example 2]
Except for using titanium oxide (TiO ₂ ) powder having a specific surface area of 20.1 m ² / g and niobium oxide (Nb ₂ O ₅ ) powder having a specific surface area of 16.1 m ² / g, the same as in Example 1, A sintered body and a sputtering target were prepared.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Comparative Example 3]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the sintering temperature was 800 ° C. and the sintering time was 10 minutes.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Comparative Example 4]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the sintering temperature was 1300 ° C. and the sintering time was 10 hours.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.3.

[Comparative Example 5]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the pressure during sintering was 5 MPa.

  Measurements and tests were performed in the same manner as in Example 1. In the X-ray diffraction of the obtained sintered body, a diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Comparative Example 6]
The sintered body and the sputtering target were produced in the same manner as in Example 1 except that the slurry was naturally dried in a high-temperature bath and the obtained powder was pulverized to 300 μm or less to obtain a granulated powder. .

  Measurements and tests were performed in the same manner as in Example 1. In the X-ray diffraction of the obtained sintered body, a diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Comparative Example 7]
A sintered body and a sputtering target were produced in the same manner as in Example 1 except that the atomic ratio of niobium as an additive metal was 0.001.

  Measurements and tests were performed in the same manner as in Example 1. From the X-ray diffraction result of the obtained sintered body, the rutile type titanium oxide phase was the main phase in the phase structure of the sintered body, and no diffraction peak due to niobium oxide was detected.

  The obtained measurement results are shown in Table 1. In addition, the refractive index in wavelength 550nm of the film | membrane obtained by film-forming was 2.4.

[Comparative Example 8]
A sintered body was produced in the same manner as in Example 1 except that the atomic ratio of niobium as an additive metal was 0.16. However, cracks occurred during sintering, and it was impossible to process the target.

  As understood from Table 1, the relative density of the titanium oxide-based sintered bodies of Examples 1 to 9 within the scope of the present invention is 95% or more. Also, the specific resistance of the sintered body is 35.5 Ω · cm at the maximum.

Further, niobium oxide (Nb ₂ O ₅ ) or tungsten oxide (WO ₃ ) oxide does not exist in the obtained sintered body.

  On the other hand, Comparative Example 1 and Comparative Example 2 are examples in which the specific surface area of the raw material is outside the scope of the present invention. Therefore, in Comparative Example 1, the requirements for the relative density, average crystal grain size, and specific resistance of the sintered body were not satisfied, and niobium oxide was also observed. For this reason, cracks and abnormal discharge occurred. In Comparative Example 2, the sintered body density and specific resistance of the sintered body were not satisfied, and cracks and abnormal discharge occurred.

  Comparative Examples 3 to 5 are examples in which the sintering conditions are outside the scope of the present invention. Therefore, in Comparative Example 3, the requirements for the sintered body density and specific resistance were not satisfied, and niobium oxide was also present. For this reason, cracks and abnormal discharge occurred. In Comparative Example 4, the requirement for the average crystal grain size was not satisfied, and generation of cracks and abnormal discharge was observed. Further, in Comparative Example 5, the requirements for the sintered body density and specific resistance were not satisfied, niobium oxide was also present, and cracks and abnormal discharge occurred.

  In Comparative Example 6, since the granulation was performed by natural drying, niobium oxide was present. Accordingly, cracks and abnormal discharge were observed.

  Comparative Example 7 is an example in which the atomic ratio of the additive element is outside the scope of the present invention. The generation of cracks and abnormal discharges due to the fact that the average crystal grain size did not satisfy the requirements and the sintered body strength itself decreased was observed.

Claims (4)

A raw material powder made of titanium oxide powder having a specific surface area of 1 to 15 m ² / g and metal oxide powder or metal powder of metal M consisting of at least one of group 5A elements and group 6A elements on the periodic table of atoms. After mixing and pulverizing so that M / (Ti + M) is a ratio of 0.002 to 0.15 in a ratio, the obtained slurry is rapidly dried and granulated, and the obtained granulated powder is subjected to 800 to 1200 ° C., A method for producing a titanium oxide-based sintered body, comprising forming and sintering in a vacuum or in an inert gas atmosphere at a pressure of 9.8 MPa or more for 30 minutes to 5 hours. A raw material powder made of titanium oxide powder having a specific surface area of 1 to 15 m ² / g and metal oxide powder or metal powder of metal M consisting of at least one of group 5A elements and group 6A elements on the periodic table of atoms. After mixing and pulverizing so that M / (Ti + M) is a ratio of 0.002 to 0.15 in a ratio, the obtained slurry is rapidly dried and granulated, and the obtained granulated powder is subjected to 800 to 1200 ° C., A titanium oxide-based sintered body obtained by molding and sintering in a vacuum or in an inert gas atmosphere at a pressure of 9.8 MPa or more for 30 minutes to 5 hours. Including a metal M composed mainly of titanium oxide and consisting of at least one of group 5A elements and group 6A elements on the periodic table so that the atomic ratio of M / (Ti + M) is 0.002 to 0.15. And an oxide represented by M _x O _y does not exist, the relative density is 95% or more, the specific resistance is 50 Ωcm or less, and the crystal grain size is 5 μm or less. .   A sputtering target obtained by processing the titanium oxide-based sintered body according to claim 2 into a predetermined shape.