JP2011037679A - Multiple oxide sintered compact, sputtering target, multiple oxide amorphous film and production method thereof, and multiple oxide crystalline film and production method thereof - Google Patents

Abstract

A composite oxide crystalline film having low resistivity and excellent light transmittance is provided.
A composite oxide sintered body mainly composed of indium, strontium and oxygen, wherein the atoms of tin and strontium with respect to the total number of atoms of indium, strontium and tin in the composite oxide sintered body A composite oxide sintered body having a number ratio of 0 to 0.3 and 0.0001 to 0.05, a relative density of 97% or more, and an average particle size of 7 μm or less, respectively.
[Selection figure] None

Description

  The present invention relates to a composite oxide sintered body, a sputtering target, a composite oxide amorphous film and a manufacturing method thereof, and a composite oxide crystalline film and a manufacturing method thereof.

  The oxide transparent conductive film has high transmittance and conductivity in the visible light region, and is used for electrodes of various light receiving elements such as liquid crystal display elements and solar cells. Further, it is also used for heat-reflecting films for automobiles and building materials, antistatic films, anti-fogging heating elements used for refrigeration showcases, and the like. In particular, the indium oxide film is widely used as an ITO film to which tin is added or an IZO film to which zinc is added.

  In recent years, a high-resistance transparent conductive film to which tin oxide and silicon oxide are added has been proposed as an indium oxide film (Patent Document 1). Further, an indium oxide-based transparent conductive film containing tin oxide and silicon oxide that has not been crystallized has been proposed (Patent Document 2).

JP 2003-105532 A JP 2005-135649 A

  A transparent conductive film used for a display element such as a liquid crystal or an electrode of various light receiving elements such as a solar cell is required to have low resistivity and excellent light transmittance. Further, in order to cope with various forms, it is required to have excellent patternability (patterning means forming a predetermined shape). However, the high resistance transparent conductive film described in Patent Document 1 is difficult to obtain a sufficiently low resistivity, and the indium oxide-based transparent conductive film described in Patent Document 2 is not crystallized and thus has excellent patternability. There is a problem that the light transmittance is not sufficient, and the resistivity increases remarkably when crystallized by heating.

  Accordingly, an object of the present invention is to provide a complex oxide crystalline film having low resistivity and excellent light transmittance. Another object of the present invention is to provide a complex oxide amorphous film that can be easily crystallized to form the complex oxide crystalline film, a sputtering target capable of forming the complex oxide crystalline film, and the sputtering target. It is providing the complex oxide sintered compact which can be used as. Another object of the present invention is to provide a method for producing a complex oxide amorphous film and a method for producing a complex oxide crystalline film.

  That is, the present invention is a composite oxide sintered body mainly composed of indium, strontium and oxygen, and tin and strontium with respect to the total number of atoms of indium, strontium and tin in the composite oxide sintered body. Provided is a composite oxide sintered body having an atomic ratio of 0 to 0.3 and 0.0001 to 0.05, a relative density of 97% or more, and an average particle size of 7 μm or less. . Note that the composite oxide sintered body of the present invention can contain a small amount of inevitable impurities.

  Such a composite oxide sintered body has a low resistivity and is useful as a sputtering target capable of forming a composite oxide crystalline film excellent in light transmittance not only in the visible light region but also in the infrared region. . Further, according to the sputtering target, an amorphous film of a composite oxide can be formed. This complex oxide amorphous film is easily crystallized by heating, and becomes a complex oxide crystalline film having low resistivity and high light transmittance not only in the visible light region but also in the infrared region. Therefore, the complex oxide amorphous film is patterned into a predetermined shape by etching or the like and then heated to obtain a complex oxide crystalline film having a predetermined shape.

  That is, this invention provides the sputtering target which consists of the said complex oxide sintered compact. A complex oxide crystalline film formed by sputtering using such a sputtering target has low resistivity and excellent light transmittance not only in the visible light region but also in the infrared region. Moreover, such a sputtering target has few abnormal discharges at the time of film-forming, and is excellent in discharge characteristics. The sputtering target of the present invention preferably has a center line average roughness of 3 μm or less, whereby the number of abnormal discharges during film formation can be further suppressed, and a composite oxide film can be stably formed. be able to.

  The present invention also provides a complex oxide amorphous film formed by sputtering using the sputtering target, and a complex oxide crystalline film formed by heating the complex oxide amorphous film. Such a complex oxide amorphous film can be easily processed by etching or the like, and can be easily crystallized by heating or the like. Therefore, a complex oxide crystalline film molded into a desired shape can be easily obtained from the complex oxide amorphous film. The complex oxide crystalline film has a low resistivity and excellent light transmittance not only in the visible light region but also in the infrared region. The heating is preferably heating at 200 ° C. or higher. As a result, the crystallization of the complex oxide amorphous film proceeds sufficiently, and lower resistivity and better light transmittance in the visible light region and the infrared region are obtained.

  The present invention also provides a complex oxide crystalline film formed on a heated substrate by sputtering using the sputtering target. Such a complex oxide crystalline film has a low resistivity and excellent light transmittance not only in the visible light region but also in the infrared region. The heating is preferably heating at 200 ° C. or higher. Thereby, the above effect can be obtained more effectively.

  The complex oxide crystalline film preferably exhibits a diffraction pattern having a bixbyite structure in X-ray diffraction measurement using Cu as a radiation source. Here, the diffraction pattern of the bixbite type structure is shown, and the diffraction peak detected in the range of 2θ = 20 to 40 ° is a (211) plane of the bixbite type structure of indium oxide, (222) plane, This is a peak indexed on the (400) plane and (411) plane. The complex oxide crystalline film exhibiting such a diffraction pattern has a low resistance and good light transmission not only in the visible light region but also in the infrared region, and particularly in the near ultraviolet region to the visible light region of 280 to 500 nm. The light transmittance in the wavelength range is further improved.

  The present invention provides a method for producing a complex oxide amorphous film formed by sputtering using the above sputtering target. The present invention also provides a method for producing a composite oxide crystalline film, in which a composite oxide amorphous film formed by sputtering using the sputtering target is heated. According to such a method, it is possible to easily obtain a complex oxide crystalline film having low resistance and good light transmittance not only in the visible light region but also in the infrared region.

  According to the present invention, it is possible to provide a complex oxide crystalline film having a low resistivity and excellent light transmittance not only in the visible light region but also in the infrared region. Also, a composite oxide amorphous film that can be easily crystallized to form the composite oxide crystalline film, a sputtering target that can form the composite oxide crystalline film, and a composite that can be used as the sputtering target An oxide sintered body can be provided. Furthermore, a method for producing a complex oxide amorphous film and a method for producing a complex oxide crystalline film can be provided.

(Composite oxide sintered body)
The composite oxide sintered body according to the present embodiment is a composite oxide sintered body mainly composed of indium, strontium and oxygen, and is a total of indium, strontium and tin in the composite oxide sintered body. The ratio of the number of atoms of tin and strontium to the number of atoms is 0 to 0.3 and 0.0001 to 0.05, respectively, the relative density is 97% or more, and the average particle size is 7 μm or less. Such a composite oxide sintered body has a low resistivity and is useful as a sputtering target capable of forming a composite oxide crystalline film excellent in light transmittance not only in the visible light region but also in the infrared region. . Further, according to the sputtering target, an amorphous film of a composite oxide can be formed. This complex oxide amorphous film is easily crystallized by heating, and becomes a complex oxide crystalline film having low resistivity and high light transmittance not only in the visible light region but also in the infrared region. Therefore, a complex oxide crystalline film having a predetermined shape can be obtained by patterning the complex oxide amorphous film into a predetermined shape by etching or the like and then heating.

  The composite oxide sintered body mainly composed of indium, strontium and oxygen means that the total number of indium, strontium and oxygen is 85% or more based on the total number of atoms constituting the composite oxide sintered body. Show. This total is preferably 90% or more.

  The ratio of the number of tin atoms to the total number of indium, strontium, and tin atoms in the composite oxide sintered body is preferably 0.01 to 0.25, more preferably 0.05 to 0.00. 2, more preferably 0.07 to 0.17. When the content of tin in the composite oxide sintered body is within the above range, the resistivity of the obtained composite oxide crystalline film and the light transmittance in the visible light region and the infrared region become better. Moreover, the complex oxide amorphous film obtained from such a complex oxide sintered body becomes a complex oxide crystalline film crystallized by heating.

  The ratio of the number of strontium atoms to the total number of indium, strontium and tin in the composite oxide sintered body is preferably 0.0005 to 0.045, more preferably 0.001 to 0.00. 04. When the content of strontium in the composite oxide sintered body is within the above range, the resistivity of the composite oxide film formed using the composite oxide sintered body as a sputtering target, the visible light region, and the infrared region. The light transmittance in the region becomes better.

The relative density indicates a value obtained by the following calculation method.
The weight ratio is determined by converting indium, tin and strontium in the composite oxide sintered body into indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ) and strontium oxide (SrO), respectively. The weight ratios of In ₂ O ₃ , SnO ₂ and SrO determined here are a%, b% and c%, respectively. Then, the true density, _{an In} 2 _{O 3} is 7.18g ^/ cm 3, SnO ₂ is 6.95 g ^/ cm 3, SrO as 4.7 g / cm ^3, the theoretical density from the following formula (I) A (g / Cm ³ ).
A = (a + b + c) / ((a / 7.18) + (b / 6.95) + (c / 4.7)) (I)

Further, the sintered density B (g / cm ³ ) of the composite oxide sintered body is measured by Archimedes method in accordance with JIS-R1634-1998.

From the theoretical density A and the sintered density B thus obtained, the relative density (%) is obtained by the following formula (II).
Relative density (%) = (B / A) × 100 (II)

  The relative density of the composite oxide sintered body is 97% or more, preferably 98% or more, and more preferably 99% or more. As a result, the resulting composite oxide crystalline film has a lower resistance, and the light transmittance tends to be better not only in the visible light region but also in the infrared region.

  The average particle size is, for example, one surface of the composite oxide sintered body, which is subjected to mirror polishing and chemical etching with a hydrochloric acid solution to obtain an observation surface. The observation surface is observed with a scanning electron microscope, and the observation photograph is used. Can be measured.

  The average particle size of the composite oxide sintered body is preferably 5 μm or less, more preferably 4 μm or less. As a result, the obtained complex oxide crystalline film has a lower resistance, and is more excellent in light transmittance not only in the visible light region but also in the infrared region. Moreover, the sputtering target which consists of complex oxide sintered compact whose average particle diameter is below the said upper limit can reduce effectively generation | occurrence | production of the nodule which becomes a cause of abnormal discharge. On the other hand, the average particle size is usually 0.001 μm or more. In order to obtain a composite oxide sintered body having an average particle size of less than 0.001 μm, for example, a raw material powder having an average primary particle size of less than 0.001 μm is used. When such a raw material powder is used, it becomes very difficult to mold, and the production efficiency tends to decrease.

  Next, the manufacturing method of the composite oxide sintered body according to the present embodiment will be described.

  The composite oxide sintered body is obtained, for example, by mixing raw metal compounds so that the ratio of the number of atoms of tin and strontium to the total number of atoms of indium, strontium and tin is within the above range, and firing the mixture .

  As the raw material metal compound, metal oxides (indium oxide, tin oxide, strontium oxide, and complex oxides thereof), metal nitrates, metal chlorides, metal carbonates, metal alkoxides, metal hydroxides, and the like can be used. Among these, indium oxide is preferable as an indium source, tin oxide is preferable as a tin source, and strontium oxide and strontium carbonate are preferable as a strontium source because of good handling properties and efficient production of a composite oxide sintered body. .

  The raw material metal compound is preferably in the form of a powder, and the handleability is further improved, so that the average particle size is preferably 1.5 μm or less, more preferably 0.1 to 1.5 μm. . Thus, by preparing the average particle diameter of the raw material metal compound, a complex oxide sintered body having a relative density within the predetermined range can be easily obtained.

  The mixing of the raw material metal compounds can be performed by dry or wet mixing, and the mixing method is not particularly limited. Examples of the mixing method include dry and wet media agitation mills using balls and beads such as zirconia, alumina, and nylon resin, medialess container rotation mixing, mechanical agitation mixing, and the like. . More specifically, a ball mill, a bead mill, an attritor, a vibration mill, a planetary mill, a jet mill, a V-type mixer, a paddle type mixer, a biaxial planetary stirring type mixer, and the like can be given.

  When mixed by a wet method such as a ball mill, a bead mill, an attritor, a vibration mill, a planetary mill, or a jet mill, the mixture is preferably dried before firing. In addition, when raw material metal compounds are mixed by the liquid phase method, that is, when a metal salt solution or alkoxide solution is used as a raw material, precipitates precipitated mainly from the solution (mainly a mixture of raw metal hydroxides) It is preferable to perform baking after recovering and drying. The drying method is not particularly limited, and can be performed by filtration drying, fluidized bed drying, spray drying, or the like.

  The mixture obtained by the above mixing may be calcined before firing. The calcination temperature is preferably 500 to 1200 ° C., and the calcination time is preferably 1 to 3 hours. The calcined powder obtained by calcining is preferably crushed to have an average particle size of 0.1 to 1.5 μm. Moreover, the calcined powder may improve the operability in the subsequent steps by granulation treatment or the like. In particular, when the raw metal compound is a metal salt, or when a mixture is prepared by a liquid phase method, it is preferable to perform such calcination.

  Moreover, it is preferable to shape | mold the said mixture in a desired shape, after calcining as needed. The molding method is not particularly limited, and a molding method that can be molded into a desired shape, such as a press molding method or a cast molding method, can be appropriately selected. The pressure at the time of molding is preferably a pressure at which a molded body that can be handled without cracks is obtained. Moreover, it is preferable to shape | mold so that the density of a molded object may become as high as possible, From this viewpoint, it is preferable to shape | mold by methods, such as cold isostatic pressing (CIP).

  In the molding method, an organic additive for improving moldability can be used as necessary. In the case of molding using such an additive, it is preferable to sufficiently remove moisture and organic additives remaining in the molded body, and examples of the removal method include a method of heating the molded body. The heating temperature can be appropriately selected according to the amount of remaining moisture, the amount of remaining organic additive, the type of organic additive, and the like, and is preferably 80 to 500 ° C.

  The firing is not particularly limited as long as the relative density and the average particle diameter of the composite oxide sintered body satisfy the above numerical range. For example, the heating rate is 10 to 400 ° C./hour (preferably 10 to 200). ° C./hour), sintering holding temperature 1400 ° C. to 1650 ° C. (preferably 1500 ° C. to 1650 ° C.), sintering holding time 1 hour or more (preferably 5 to 20 hours), cooling rate 10 to 500 ° C. / Hour (preferably 100 to 500 ° C./hour from sintering holding temperature to 1200 ° C., 10 to 100 ° C./hour from 1200 ° C.). Although these conditions may be changed as appropriate, the effects of shortening the firing time and preventing cracking of the composite oxide sintered body are exhibited when the rate of temperature rise and the rate of temperature fall are within the above ranges. Moreover, when the sintering holding temperature is within the above range, the solid solution of tin oxide in the indium oxide lattice is promoted, and the effects of the present invention can be obtained better. Furthermore, when the sintering holding time is within the above range, a high-density composite oxide sintered body can be easily obtained.

  Firing is preferably performed in an oxygen-containing atmosphere, and more preferably in an oxygen stream. Furthermore, in firing in an oxygen stream, the ratio of the value of the oxygen flow rate (L / min) when introducing oxygen into the furnace and the value of the charge amount (kg) of the above mixture is the charge amount / oxygen flow rate. It is preferable to introduce oxygen into the furnace so as to be 1.0 or less. Thereby, it becomes easy to obtain a high-density composite oxide sintered body, and the effect of the present invention is further improved.

  The composite oxide sintered body having a relative density of 97% or more and an average particle size of 7 μm or less has an average particle size of the raw metal compound of 0.1 to 1.5 μm and a sintering holding temperature of 1500 to 1650 ° C., for example. It can be easily manufactured by setting the sintering holding time to 2 to 10 hours, and the temperature decreasing rate during sintering from 100 to 500 ° C./hour from the sintering holding temperature to 1200 ° C.

(Sputtering target)
The sputtering target according to the present embodiment is characterized by comprising the composite oxide sintered body. A complex oxide crystalline film formed by sputtering using such a sputtering target has low resistivity and excellent light transmittance not only in the visible light region but also in the infrared region. Moreover, since such a sputtering target is excellent in the discharge characteristic at the time of film-forming, it can form a complex oxide film stably. In the present embodiment, the complex oxide sintered body may be used as it is as a sputtering target, or the complex oxide sintered body may be processed into a predetermined shape as a sputtering target.

  In the sputtering target, the surface roughness of the sputtering surface is preferably 3 μm or less, more preferably 2 μm or less, in terms of centerline average roughness (Ra). As a result, the number of abnormal discharges during film formation can be further suppressed, and a complex oxide film can be formed stably. The centerline average roughness can be adjusted by a method such as a method of machining the sputter surface of the composite oxide sintered body with a grindstone or the like having a different count, a method of spraying with a sandblast or the like. The centerline average roughness can be determined by, for example, evaluating the measurement surface with a surface texture measuring device.

(Composite oxide crystalline film)
The composite oxide crystalline film according to this embodiment is formed by sputtering using the above sputtering target, and such a composite oxide crystalline film has a low resistivity and is only in the visible light region. In addition, it is excellent in light transmittance even in the infrared region.

  The complex oxide crystalline film is preferably formed by a sputtering method using a sputtering target. As a sputtering method, a DC sputtering method, an RF sputtering method, a DC magnetron sputtering method, an RF magnetron sputtering method, an ion beam sputtering method, or the like can be selected as appropriate, and among these, a large area can be uniformly formed at a high speed. Therefore, the DC magnetron sputtering method and the RF magnetron sputtering method are preferable.

  The composite oxide crystalline film can be manufactured by heating a composite oxide amorphous film formed by sputtering using the sputtering target. The complex oxide crystalline film manufactured in this way has a low resistivity and is further excellent in light transmittance in the visible light region and the infrared region. The heating temperature is preferably 200 ° C. or higher. As a result, the crystallization of the complex oxide amorphous film proceeds sufficiently, and better resistivity and light transmittance in the visible light region and the infrared region can be obtained.

  The complex oxide amorphous film is excellent in light transmittance in the visible light region and the infrared region, and can be easily processed by etching or the like. Therefore, a complex oxide crystalline film having a predetermined shape can be manufactured by heating a complex oxide amorphous film formed by sputtering using a sputtering target and patterned by etching or the like. it can.

  The complex oxide amorphous film is formed at a film formation temperature at which film crystallization does not occur, for example, room temperature (about 25 ° C.) to 150 ° C. or less. The film formation temperature can be appropriately selected from the temperature below the upper limit value according to the characteristics of the substrate and the like. However, the lower the temperature, the less the restrictions on the apparatus and material, so that the temperature is 100 ° C. or less. preferable.

  The complex oxide amorphous film is crystallized by heating to 200 ° C. or higher to become a complex oxide crystalline film. This heating may be performed in the air, in a non-oxidizing gas atmosphere such as nitrogen or argon, in an inert gas atmosphere, or in a vacuum. Although the heating time depends on the heating temperature and the atmosphere, crystallization is usually completed within several hours.

  The complex oxide crystalline film can also be manufactured by forming a film on a heated substrate by sputtering using a sputtering target. The composite oxide crystalline film manufactured in this way is crystalline as a whole, has a uniform low resistivity, and is further excellent in light transmittance in the visible light region and the infrared region. The heating temperature of the substrate is preferably 200 ° C. or higher, whereby the above effect can be obtained more effectively.

  Here, the complex oxide crystalline film refers to a film in which the complex oxide constituting the film has a substantially crystalline structure. The complex oxide amorphous film refers to a film in which the complex oxide constituting the film has substantially no crystal structure. In the present embodiment, having substantially a crystal structure means that a diffraction pattern derived from the crystal structure is observed in X-ray diffraction measurement, and not having a crystal structure substantially means that X This means that the diffraction pattern derived from the crystal structure is not observed in the line diffraction measurement.

  The complex oxide crystalline film preferably exhibits a bixbite structure diffraction pattern in X-ray diffraction measurement using Cu as a radiation source. Here, a diffraction pattern of a bixbite structure is shown. The diffraction peaks detected in the range of 2θ = 20 to 40 ° are (211) plane, (222) plane of bixbite structure of indium oxide, ( 400) plane and (411) plane. A complex oxide crystalline film exhibiting such a diffraction pattern has a bigbite type crystal structure, low resistance and good light transmission not only in the visible light region but also in the infrared region. The light transmittance in the wavelength range of 280 to 500 nm from the region to the visible light region is further improved.

  The reason why such an effect can be obtained by having the big oxide type crystal structure in the complex oxide crystalline film is not necessarily clear, but the electron orbit overlap is good and the carrier density is an appropriate amount. Thus, it is considered that the light transmittance in the wavelength range of 280 to 500 nm is further improved.

  The complex oxide crystalline film according to the present embodiment has low resistance and good light transmission not only in the visible light region but also in the infrared region. It can utilize suitably as a transparent conductive film used for the electrode etc. of an element.

  The present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

(Examples 1-8, Comparative Examples 1-6)
Indium oxide powder having a purity of 99.99% and an average particle size of 0.5 μm, a purity of 99.99%, and an average particle size of 0.8 so that the ratio of the number of atoms of indium, tin, and strontium is the value shown in Table 1. 5 μm tin oxide powder and strontium carbonate powder having a purity of 99.9% and an average particle diameter of 1 μm were mixed in a dry ball mill. Subsequently, after calcining in air | atmosphere at 1000 degreeC for 2 hours, it crushed with the dry-type ball mill. The obtained powder was CIP-molded at 3.0 ton / cm ² , placed in a pure oxygen atmosphere sintering furnace, and sintered under the following conditions to obtain a composite oxide sintered body.

[Sintering conditions]
・ Temperature increase rate: 50 ° C./hour ・ Sintering temperature: 1600 ° C.
-Holding time: 5 hours-Sintering atmosphere: Pure oxygen gas is introduced into the furnace from room temperature when the temperature is raised to 100 ° C when the temperature is lowered-Oxygen flow rate: Charged weight (kg) / Oxygen flow rate (L / min) = 0 .8
・ Cooling rate: 100 ℃ / hour

  The characteristics of the obtained composite oxide sintered body were evaluated as follows. The evaluation results are shown in Table 1.

[Method for measuring sintered density of composite oxide sintered body]
The sintered density of the composite oxide sintered body was measured by Archimedes method in accordance with JIS-R1634-1998. From this sintered density, the relative density was determined by the method described above.

[Measuring method of average particle diameter of composite oxide sintered body]
After the composite oxide sintered body was cut to an appropriate size, the observation surface was mirror-polished, and then chemical etching was performed with a hydrochloric acid solution. This observation surface was observed using a scanning electron microscope or the like, and the average particle diameter was determined from the observation photograph.

  Next, the composite oxide sintered body was processed into a 4-inch φ size, and a sputter surface was produced by machining with a surface grinder using a diamond grindstone to obtain a sputtering target. About the obtained sputtering target, centerline average roughness and discharge characteristics were evaluated as follows. The evaluation results are shown in Table 1.

[Measurement method of centerline average roughness of sputtering target]
The sputtering surface of the sputtering target was used as the measurement surface, and the measurement surface was evaluated with a surface property measuring device (SV-3100, manufactured by Mitutoyo Corporation) to determine the centerline average roughness.

[Evaluation of discharge characteristics of sputtering target]
The number of abnormal discharges generated per hour was observed under the following sputtering conditions.
<Sputtering conditions>
・ Equipment: DC magnetron sputtering equipment (manufactured by ULVAC)
Magnetic field strength: 1000 Gauss (directly above the target, horizontal component)
-Substrate temperature: Room temperature (about 25 ° C)
・ Achieved vacuum: 5 × 10 ⁻⁵ Pa
Sputtering gas: Argon + oxygen (volume ratio of oxygen is 0.5%)
・ Sputtering gas pressure: 0.5 Pa
・ DC power: 300W
・ Sputtering time: 30 hours

  Next, using the obtained sputtering target as a target, a complex oxide film was obtained by DC magnetron sputtering under the following conditions. Further, the obtained composite oxide film was heated in the atmosphere at 250 ° C. for 1 hour.

[Sputtering film formation conditions]
・ Equipment: DC magnetron sputtering equipment (manufactured by ULVAC)
Magnetic field strength: 1000 Gauss (directly above the target, horizontal component)
-Substrate temperature: Room temperature (about 25 ° C)
・ Achieved vacuum: 5 × 10 ⁻⁵ Pa
Sputtering gas: Argon + oxygen (The volume ratio (%) occupied by oxygen is shown in Table 2 as the amount of oxygen.)
・ Sputtering gas pressure: 0.5 Pa
・ DC power: 300W
-Film thickness: 150 nm
-Substrate used: non-alkali glass (Corning # 1737 glass)
Thickness 0.7mm

  The characteristics of the composite oxide film before and after heating were measured as follows. The measurement results are shown in Table 2.

[Composition of composite oxide film]
Indium, tin, and strontium were quantified by ICP emission analysis using an ICP emission spectroscopic analyzer (manufactured by Seiko Instruments Inc.). As a result of quantification, indium, tin, and strontium in the composite oxide film were contained in a ratio almost the same as the ratio of the number of atoms at the time of manufacturing the composite oxide sintered body.

[Evaluation of crystallinity of composite oxide film]
An X-ray diffraction test was performed under the following measurement conditions, and a diffraction pattern having a bixbite structure (specifically, detected within a range of 2θ = 20 to 40 °, (211) plane, (222) plane, (400 ) And (411) peaks indexed were evaluated as crystalline, and those not observed were evaluated as amorphous. Note that a diffraction pattern showing a crystal structure other than the bixbite structure was not observed.
<Measurement conditions>
-X-ray source: CuKα
・ Power: 40kV, 40mA
・ Scanning speed: 1 ° / min

[Measurement of resistivity of composite oxide film]
Using HL5500 manufactured by Nippon Bio-Rad Laboratories, the resistivity of the composite oxide film was measured by the four-probe method.

[Measurement of light transmittance of composite oxide film]
The light transmittance including the substrate was a spectrophotometer U-4100 (manufactured by Hitachi, Ltd.). The measurement range was a wavelength from 240 nm to 2600 nm. Among the measurement results, light transmittances at 400 nm, 550 nm and 1200 nm are shown in Table 2.

[Evaluation of crystallization temperature of composite oxide film]
The sample obtained by heating the complex oxide film formed on the substrate at 100 ° C., 150 ° C., 200 ° C., and 250 ° C. for 1 hour was subjected to the above-described crystallinity evaluation, and the presence or absence of crystallization was observed.

(Examples 9 to 10, Comparative Examples 7 to 8)
Indium oxide powder having a purity of 99.99% and an average particle size of 0.5 μm, a purity of 99.99%, and an average particle size of 0.8 so that the ratio of the number of atoms of indium, tin, and strontium is the value shown in Table 3. 5 μm tin oxide powder and strontium carbonate powder having a purity of 99.9% and an average particle diameter of 1 μm were mixed in a dry ball mill. Subsequently, after calcining in air | atmosphere at 1000 degreeC for 2 hours, it crushed with the dry-type ball mill. The obtained powder was CIP-molded at 3.0 ton / cm ² , placed in a pure oxygen atmosphere sintering furnace, and sintered under the following conditions to obtain a composite oxide sintered body.

[Sintering conditions]
-Temperature rising rate: 50 ° C / hour-Sintering temperature: 1600 ° C (Examples 9 and 10, Comparative Examples 8 and 9)
1300 ° C. (Comparative Example 7)
Holding time: 5 hours (Examples 9 and 10, Comparative Examples 7 and 9)
24 hours (Comparative Example 8)
・ Sintering atmosphere: Pure oxygen gas is introduced into the furnace from room temperature when the temperature is raised to 100 ° C. when the temperature is lowered. ・ Oxygen flow rate: charged weight (kg) / oxygen flow rate (L / min) = 0.8
・ Cooling rate: 100 ℃ / hour

  The properties of the obtained composite oxide sintered body were evaluated by the above methods. The evaluation results are shown in Table 3.

  Next, the composite oxide sintered body was processed into a 4-inch φ size, and a sputter surface was produced by machining with a surface grinder using a diamond grindstone to obtain a sputtering target. At this time, the center line average roughness of the sputtering target was adjusted by appropriately adjusting the count of the diamond grindstone. About the obtained sputtering target, the center line average roughness and the discharge characteristics were evaluated by the above method. The evaluation results are shown in Table 3.

  Next, using the obtained sputtering target as a target, a complex oxide film was obtained by DC magnetron sputtering under the following conditions. Further, the obtained composite oxide film was heated at 250 ° C. for 1 hour.

[Sputtering film formation conditions]
・ Equipment: DC magnetron sputtering equipment (manufactured by ULVAC)
Magnetic field strength: 1000 Gauss (directly above the target, horizontal component)
-Substrate temperature: Room temperature (about 25 ° C)
・ Achieved vacuum: 5 × 10 ⁻⁵ Pa
Sputtering gas: Argon + oxygen (The volume ratio of oxygen is described in Table 4 as the amount of oxygen.)
・ Sputtering gas pressure: 0.5 Pa
・ DC power: 300W
-Film thickness: 150 nm
-Substrate used: non-alkali glass (Corning # 1737 glass)
Thickness 0.7mm

  The characteristics of the composite oxide film before and after heating were measured by the above methods. Table 4 shows the measurement results.

  As described above, the composite oxide amorphous film can be obtained by setting the ratio of the number of tin and strontium atoms, the relative density, and the average particle size in the composite oxide sintered body to predetermined values. This amorphous film can be easily crystallized, and a complex oxide crystalline film having low resistance and excellent light transmittance not only in the visible light region but also in the infrared light region can be obtained. Furthermore, a sputtering target made of such a complex oxide sintered body has stable discharge characteristics.

Claims (11)

A composite oxide sintered body mainly composed of indium, strontium and oxygen,
The ratio of the number of atoms of tin and strontium to the total number of atoms of indium, strontium and tin in the composite oxide sintered body is 0 to 0.3 and 0.0001 to 0.05, respectively, and the relative density is A composite oxide sintered body having 97% or more and an average particle size of 7 μm or less.   A sputtering target comprising the composite oxide sintered body according to claim 1.   The sputtering target according to claim 2, wherein the center line average roughness is 3 μm or less.   A composite oxide amorphous film formed by sputtering using the sputtering target according to claim 2.   A complex oxide crystalline film obtained by heating the complex oxide amorphous film according to claim 4.   The complex oxide crystalline film according to claim 5, wherein the heating is heating at 200 ° C. or higher.   A complex oxide crystalline film formed on a heated substrate by sputtering using the sputtering target according to claim 2.   The complex oxide crystalline film according to claim 7, wherein the heating is heating at 200 ° C. or higher.   The complex oxide crystalline film according to any one of claims 5 to 8, which shows a diffraction pattern having a bixbite structure in X-ray diffraction measurement using Cu as a radiation source.   A method for producing a complex oxide amorphous film, which is formed by sputtering using the sputtering target according to claim 2.   A method for producing a composite oxide crystalline film, comprising heating a composite oxide amorphous film formed by sputtering using the sputtering target according to claim 2.