JP2014024738A - Igzo sintered body, sputtering target, and oxide film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an IGZO (In-Ga-Zn-O) sintered body in which a density and a flexural strength are high, and a crack is few even when being used for a sputtering target; a production method of the same; and an oxide film that is excellent in permeability and mobility by using the sputtering target.SOLUTION: An oxide sintered body in which a density and a flexural strength are high can be prepared by adding at least 20 ppm and less than 100 ppm by a weight ratio of zirconium to a sintered body having a homologous crystal structure represented by InGaZnO. Furthermore, the sintered body is used for a target material, thereby an oxide semiconductor film having favorable permeability and mobility can be prepared.

Description

  The present invention relates to a sputtering target used for forming an In—Ga—Zn—O (IGZO) semiconductor thin film made of indium, gallium, zinc and oxygen used for a thin film transistor (TFT), and an oxidation obtained using the target. It relates to material films.

  In recent years, various flat panel displays (FPD) such as organic electroluminescence (EL) and flexible displays have been proposed, and TFTs capable of forming a thin film at a low temperature and having relatively high mobility are desired. An IGZO semiconductor thin film can be formed at a lower temperature than a crystalline silicon thin film and has a higher mobility than an amorphous silicon thin film, and thus has attracted attention as a TFT material for FPD (for example, Patent Document 1, 2). Further, since the IGZO film has visible transparency, it is used for various applications such as switching elements such as liquid crystal display elements and drive circuit elements. In such applications, thin film materials having as high a transmittance as possible are desired.

  These IGZO thin films are formed by sputtering because the area can be easily increased and a high performance film can be obtained. Generally, an IGZO sintered body is used as a target in both a flat plate sputtering target and a cylindrical sputtering target. As the IGZO sintered body, those having a homologous crystal structure having a layered structure are mainly used, but the strength of the sintered body is low due to anisotropy due to the layered structure, and the thermal stress due to plasma during discharge is low. When concentrated on a specific part, there was a problem that the target was easily cracked by the stress.

As a method for improving the strength of an IGZO sintered body, Patent Document 3 discloses that the bending strength is increased to 58 MPa by using a crystal phase including a spinel structure. In Patent Document 4, a bending strength of 14.3 kg / mm ² (about 140 MPa) is obtained by using a crystal phase including a spinel structure and a bixbite. However, since the composition of the IGZO film is limited by these methods, the composition ratio of In, Ga and Zn in the IGZO sintered body cannot be determined as appropriate in order to optimize the film characteristics. A method for increasing the strength of a sintered body without depending on the composition ratio of the body has been desired. In particular, in the case of a composition ratio having only a homologous crystal structure, since the strength is remarkably low, it has been strongly desired to improve the strength of the sintered body.

  As a method for improving the strength of the sintered body, it is known that densification of the sintered body is effective. However, since the crystal growth of the IGZO sintered body is relatively fast, pores (bubbles) are sintered. It is difficult to obtain a high-density sintered body that tends to remain inside the body. In Patent Document 5, a sintered body having a density of 98% is obtained with a sintering holding time of 20 hours or longer. However, since the crystal growth of the sintered body is promoted, the grain size becomes as large as 7 μm and there is no description of the strength of the sintered body, but generally when the grain size grows in this way, the sintered body The strength of is low. In particular, in the case of a sintered body having only a layered structure such as a homologous structure, the strength is likely to further decrease.

Also known is a method for improving the properties by adding impurities to the sintered body. Patent Documents 6 and 7 contain 100 ppm to 10,000 ppm of a metal element having a positive tetravalent or higher in an IGZO target, and the sintered body. Is reduced to less than 1 × 10 ⁻³ Ω · cm to reduce arcing. However, when a large amount of impurities are added, the characteristics of the IGZO film may be deteriorated. It is not an effective method.

Japanese Patent Laid-Open No. 2000-044236 JP 2004-103957 A JP 2008-163441 A Patent International Publication 2011/04/04 Pamphlet Patent International Publication No. 2009/157535 Pamphlet Patent International Publication WO2008 / 072486 Pamphlet Patent International Publication WO2009 / 157535 Pamphlet

  An object of the present invention is to provide an IGZO sintered body having a high density and bending strength, and having few cracks even when used for a sputtering target, and a method for producing the same. Another object is to provide an oxide film having high transmittance and mobility using the target.

As a result of intensive studies, the present inventors have made the sintered body having a homologous crystal structure represented by InGaZnO ₄ contain zirconium having a weight ratio of 20 ppm or more and less than 100 ppm, thereby reducing the relative density of the sintered body. 95% or higher, bending strength can be increased to 100 MPa or more, and the IGZO film obtained by sputtering using this sintered body exhibits excellent transmittance compared to that without adding zirconium. As a result, the present invention has been completed.

Aspects of the present invention are as follows.
(1) An oxide sintered body containing In, Ga, and Zn, having a homologous crystal structure represented by InGaZnO ₄ , and containing zirconium at a weight ratio of 20 ppm or more and less than 100 ppm Sintered body.
(2) The sintered body according to (1), wherein the relative density is 95% or more and the bending strength is 100 MPa or more.
(3) The sintered body according to (1) or (2), wherein the area of the target surface is 961 cm ² or more and the shape is a flat plate shape.
(4) The sintered body according to (1) or (2), wherein the area of the target surface is 257 cm ² or more and the shape is cylindrical.
(5) A sputtering target using the sintered body according to (1) to (4) described above as a target material.
(6) An oxide film obtained by sputtering the sputtering target according to (5) above.

  Hereinafter, the present invention will be described in detail.

The IGZO sintered body of the present invention is a sintered body containing indium, gallium, zinc and oxygen and having a homologous crystal structure represented by InGaZnO ₄ . The “sintered body having a homologous crystal structure represented by InGaZnO ₄ ” referred to in the present invention refers to a sintered body having an X-ray diffraction pattern including a peak that matches the diffraction pattern of InGaZnO ₄ . Further, the "sintered body having only homologous crystal structure represented by InGaZnO _4" is referred to in the present invention, X-ray diffraction pattern is consistent with the diffraction pattern of InGaZnO _4, the peaks that are not attributable to the diffraction pattern of InGaZnO ₄ It means not included.

According to the present invention, by containing zirconium of 20 ppm or more and less than 100 ppm by weight in an IGZO sintered body having a homologous crystal structure represented by InGaZnO ₄ , the density and bending strength are high, and it is used for a sputtering target. Even in this case, the IGZO sintered body has few cracks. By containing 20 ppm or more of zirconium, the sinterability of IGZO is improved, and increases in the density and strength of the sintered body are recognized. The content of zirconium is preferably 30 ppm or more, more preferably 40 ppm or more.

When the zirconium content is less than 20 ppm, there is no effect of the relative density and strength of the sintered body, and when the zirconium content is 100 ppm or more, the transmittance of the produced IGZO film starts to decrease, and the TFT element using the IGZO film The field effect mobility (hereinafter referred to as “mobility”) also gradually decreases. Since the TFT element has higher FPD performance as the mobility is higher, it is not desirable to add an amount of impurities that lower the mobility to the IGZO sintered body. The mobility value is preferably as high as possible, and is preferably 15.0 cm ² / V · s or more.

  The relative density of the IGZO sintered body of the present invention is preferably 95% or more, more preferably 97% or more, and still more preferably 98% or more. When a sintered body having a relative density of less than 95% is used as a target, abnormal discharge may easily occur during sputtering, and the quality of the film may deteriorate due to particles generated by abnormal discharge, which may reduce the yield. Because there is.

  The bending strength of the IGZO sintered body of the present invention is preferably 100 MPa or more. If the strength of the sintered body is high, cracks are less likely to occur during grinding, and the yield is high, so the productivity is good. Furthermore, even when used for a cylindrical sputtering target in which high power is applied during sputtering, the problem of cracking is unlikely to occur. In the present invention, the bending strength was measured according to a three-point bending test of JIS R 1601.

  Moreover, the IGZO film produced using this sintered body as a sputtering target has a higher transmittance than that containing no zirconium, and the TFT element using the IGZO film of the present invention is an element not containing zirconium. In comparison, the mobility is the same, and the TFT element characteristics are not deteriorated. The zirconium content in the sintered body can be measured by ICP (inductively coupled plasma) analysis.

Incidentally, the sintering the sintered body of indium, gallium and zinc ratio is not particularly limited as long as the composition containing a homologous crystal structure represented by InGaZnO _4, having only the homologous crystal structure represented by InGaZnO ₄ Since the body is extremely weak, the effect of the present invention is great and suitable.

  Next, the manufacturing method of the sintered compact of this invention is demonstrated for every process.

(1) Raw material mixing step The raw material powder is not particularly limited. For example, metal salt powder such as indium, gallium, zinc, zirconium or its chloride, nitrate, carbonate can be used. In view of the properties, oxide powder is preferable.

  The purity of each raw material powder is preferably 99.9% or more, more preferably 99.99% or more. This is because if the purity is low, an adverse effect may be exerted on the TFT formed by the sputtering target using the IGZO sintered body of the present invention due to the contained impurities.

The composition of these raw materials is not particularly limited as long as it is a composition that generates a homologous crystal structure represented by InGaZnO ₄ , but is a composition of In: Ga: Zn = 1: 1: 1 in terms of the atomic ratio of metal elements. The strength is low and the effect of the present invention is great. What is necessary is just to add zirconium content so that it may become 20 ppm or more and less than 100 ppm by weight ratio.

  The mixing of each of these powders is not particularly limited, but dry type using a ball or bead such as alumina or nylon resin, wet type media stirring type mill, medialess container rotating type mixing, mechanical stirring type mixing, etc. The mixing method is exemplified. Specific examples include a ball mill, a bead mill, an attritor, a vibration mill, a planetary mill, a jet mill, a V-type mixer, a paddle mixer, and a twin-shaft planetary agitation mixer. When zirconia balls or beads are used for mixing, the amount of raw material powder is adjusted in consideration of the amount of zirconium mixed in from the balls or beads.

In addition, pulverization is performed simultaneously with the mixing of the powder, but if the average particle size of the powder is large, the density after firing may not be sufficiently increased. Therefore, it is preferable that the powder particle size after pulverization is finer. The average particle size of the powder is preferably 1.0 μm or less, more preferably 0.1 to 1.0 μm, when measured by a laser diffraction / scattering method. Further, the specific surface area of the powder measured by the BET method is preferably 11 cm ² / g or more, and more preferably 12 cm ² / g or more. By doing so, it becomes possible to obtain a sintered body having small sintered particles and a high sintered density. When a wet ball mill, bead mill, attritor, vibration mill, planetary mill, jet mill or the like is used, it is necessary to dry the pulverized slurry. This drying method is not particularly limited, and examples thereof include filtration drying, fluidized bed drying, and spray drying.

Further, if or mix to advance generate InGaZnO ₄ to use a powder other than oxide powder may also be carried out calcination at 900 to 1200 ° C. after mixing. When the particle size of the calcined powder becomes large, the average particle size is preferably 1.0 μm or less, more preferably 0.1 to 1.0 μm, by pulverization. In the molding process, molding aids such as polyvinyl alcohol, acrylic polymer, methylcellulose, waxes, and oleic acid may be added to the raw material powder.

(2) Molding process The molding method can be appropriately selected from a molding method that can form a mixed powder of raw material powders (a calcined mixed powder when calcined) into a desired shape, and is particularly limited. Is not to be done. Examples thereof include a press molding method, a casting molding method, and an injection molding method.

The molding pressure is not particularly limited as long as it does not cause cracks in the molded body and can be handled, but it is preferable to increase the molding density as much as possible. Therefore, it is also possible to use a method such as cold isostatic pressing (CIP) molding. CIP pressure is preferably for 1 ton / cm ² or more to obtain a sufficient consolidation effect, more preferably 2 ton / cm ² or more, especially preferably 2~3ton / cm ^2.

  Here, when the first molding is performed by a casting method and then CIP is performed, the binder may be removed for the purpose of removing moisture and organic substances such as binder remaining in the molded body after CIP. Good. Further, even when the first molding is performed by the press method, the same debinding treatment can be performed when a binder or the like is added in the raw material mixing step.

(3) Firing step The firing method is not particularly limited, and a firing method suitable for the sintering behavior of the raw material powder can be appropriately selected. Examples thereof include an electric furnace, a gas furnace, HIP (isotropic hot press), HP (hot press), and a microwave furnace.

  The firing temperature of the material to be fired is not particularly limited, but is preferably 1300 ° C. or higher and 1500 ° C. or lower in order to obtain a sintered body having high density and high strength. At a temperature higher than 1500 ° C., it is difficult to obtain a sintered body having a strength of 100 MPa or more due to growth of particles of the sintered body. On the other hand, if it is lower than 1300 ° C., the density of the sintered body may be lowered.

  The holding time of the object to be fired is not particularly limited, but is preferably 30 minutes or longer and 5 hours or shorter when firing with an electric furnace. More preferably, it is 1 hour or more and 2 hours or less. If it is shorter than 30 minutes, the sintering does not proceed sufficiently and a high-density sintered body cannot be obtained. When the time is longer than 5 hours, crystal grains grow and a high-strength sintered body cannot be obtained.

  The temperature increase rate of the object to be fired is not particularly limited, but is preferably 50 ° C./hour or more in order to shorten the firing time as much as possible to suppress the growth of crystal grains in the sintered body and obtain a high-strength sintered body. More preferably, it is 100 ° C./hour or more. However, in the case of a molded body containing moisture and a binder, especially when a large molded body is volatilized, the molded body may crack if the moisture and binder components volatilize. It is preferable to set the rate of temperature increase to 20 to 100 ° C./hour in a temperature range of 100 to 400 ° C., and to 20 to 100 ° C./hour in the temperature range of 100 to 600 ° C. Is more preferable.

  The temperature lowering rate is preferably 150 ° C./hour or more, more preferably 200 ° C./hour or more, from the firing temperature to 1100 ° C. By lowering the temperature range at 150 ° C./hour or more, oxygen taken into the surface of the sintered body can be reduced, and color unevenness on the surface of the sintered body can be suppressed. In a temperature range other than this, the temperature drop rate is not particularly limited, and can be appropriately determined in consideration of the capacity of the sintering furnace, the size and shape of the sintered body, ease of cracking, and the like.

  The atmosphere at the time of firing is not particularly limited, but is preferably an air or oxygen atmosphere in order to suppress zinc sublimation. Further, for the purpose of suppressing uneven color on the surface of the sintered body and lowering the specific resistance of the sintered body, it is possible to create a non-oxidizing atmosphere such as nitrogen when the temperature is lowered from the firing temperature.

(4) Targeting process The obtained sintered body is formed into a desired shape such as a plate shape, a circular shape, or a cylindrical shape by using a machining machine such as a surface grinder, a cylindrical grinder, a lathe, a cutting machine, or a machining center. To grind. Furthermore, the sputtering target which used the sintered compact of this invention as the target material can be obtained by joining to the backing plate and backing tube which consist of oxygen-free copper, titanium, etc. as needed using indium solder.

The size of the sintered body is not particularly limited, but since the sintered body according to the present invention has high strength, a large target can be manufactured. In the case of a flat plate-type sputtering target, a large-sized sintered body having a length of 310 mm × width of 310 mm (target surface area 961 cm ² ) or more can be produced. In the case of a cylindrical sputtering target, a large sintered body having an outer diameter of 91 mmΦ × 90 mm (target surface area 257 cm ² ) or more can be produced. The area of the target surface refers to the area of the surface of the sintered body to be sputtered, and in the case of a multi-part target composed of a plurality of sintered bodies, the side to be sputtered in each sintered body The surface area of the sintered body is the area of the target surface in the multi-division target.

  The thickness of the target is not particularly limited, but is preferably 4 mm or more and 15 mm or less. If it is thinner than 4 mm, the target utilization is low and not economical. On the other hand, if it is thicker than 15 mm, uneven sintering is likely to occur, and it is difficult to obtain a target having uniform quality up to the central portion.

  The surface roughness of the target is not particularly limited, but it takes a long time to reduce the surface roughness and is not economical, so the surface roughness (Ra) is preferably 1 μm or more.

In the present invention, a sintered body having high density and high strength can be obtained in the IGZO sintered body having a homologous crystal structure represented by InGaZnO ₄ . When such a sintered body is used as a flat plate-type sputtering target or a cylindrical sputtering target, it is possible to produce a high-quality target with less cracking and less abnormal discharge (arcing). Further, since the strength of the sintered body is high, the sintered body can be easily processed, and a large target can be manufactured with a high yield. Furthermore, the IGZO film produced by the sputtering method using the target according to the present invention exhibits excellent transmittance and mobility.

It is a figure which shows the relationship between the Zr density | concentration of the IGZO sintered compact obtained by Example 1, the comparative example 1, and the comparative example 2, and the relative density of a sintered compact. It is a figure which shows the relationship between the Zr density | concentration of the IGZO film | membrane obtained by Example 1, the comparative example 1, and the comparative example 2, and the transmittance | permeability. 6 is a schematic cross-sectional view showing the structure of a TFT device manufactured in Example 1, Comparative Example 1 and Comparative Example 2. FIG. It is a figure which shows the relationship between the Zr density | concentration of the TFT element obtained by Example 1, the comparative example 1, and the comparative example 2, and a mobility.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto. In addition, each measurement in a present Example was performed as follows.

(1) Density of sintered body The relative density of the sintered body was determined as follows. That is, first, the bulk density (d ₁ ) was measured by Archimedes method according to JIS R 1634. The theoretical density (d) of the sintered body is calculated by converting the amounts of In, Ga, and Zn in the sintered body into oxides to be indium oxide, gallium oxide, and zinc oxide, respectively. ), B (g), c (g) and their respective true densities d _a (g / cm ³ ), d _b (g / cm ³ ), d _c (g / cm ³ ) Is obtained from the arithmetic mean.
d = (a + b + c) / ((a / d _a ) + (b / d _b ) + (c / d _c ))
The relative density D of the sintered body is determined by D = (d ₁ / d) × 100 (%).

(2) X-ray diffraction measurement An X-ray diffraction pattern in a range of 2θ = 20 to 70 ° was measured, and a diffraction pattern of InGaZnO ₄ (database No. 01 of X-ray diffraction analysis software JADE 7.0 of Rigaku Corporation) -070-3626).
(Measurement conditions for X-ray diffraction test)
Scanning method: Step scan method (FT method)
X-ray source: CUKα
Power: 40kV, 40mA
Step width: 0.02 °
(3) Folding strength Measured according to JIS R 1601.
(Measurement conditions of bending strength)
Test method: 3-point bending test fulcrum distance: 30 mm
Sample size: 3x4x40mm
Head speed: 0.5 mm / min
(4) Zr concentration The Zr concentration was measured using an ICP (inductively coupled argon plasma) emission spectrometer manufactured by Seiko Instruments Inc. and an ICP mass spectrometer manufactured by PerkinElmer.

(5) Transmittance The transmittance was measured using a spectrophotometer (U-4100) manufactured by Hitachi, Ltd.

(6) TFT characteristics Measured using a voltage generator (REGULATED DC POWER SUPPLY PAS160-2) manufactured by Kikusui Electronics, a voltage measuring device manufactured by Kikusui Electronics (DIGITM ULTIMETER DME1600), and a current measuring device (DIGITAL ELECTEOMETER 8240) manufactured by ADC Corporation. did.

Example 1
Indium oxide powder, gallium oxide powder, and zinc oxide powder with a purity of 99.99% or more were weighed so that In: Ga: Zn = 1: 1: 1 in terms of atomic ratio of metal elements, Four types of mixed powders (a) to (d) were obtained by changing the addition amount of zirconium oxide. These powders were slurried with pure water, and in a state where the slurry concentration was 50 wt%, dispersion treatment was performed with a wet bead mill using 0.3 mmφ zirconia beads. At this time, a dispersant was appropriately added so that the slurry viscosity was 1000 ps or less. Next, these dispersion-treated slurries are granulated and dried with a spray dryer, and using these powders, a molded body of 150 mmΦ × 10 mmt is produced by a die press at a pressure of 300 kg / cm ² , CIP treatment was performed at a pressure of ² ton / cm ² .

  Next, this compact was fired in an electric furnace. The heating rate was 100 ° C./hour from room temperature to 1400 ° C. The firing temperature was 1400 ° C. and the holding time was 1 hour. The temperature decreasing rate was 200 ° C./hour from 1400 ° C. to 1100 ° C. Then, it was naturally cooled and taken out after the furnace temperature reached 50 ° C. or lower.

After processing the obtained sintered body to 101.6 mmΦ × 6 mmt, it was bonded to an oxygen-free copper backing plate with indium solder to obtain a sputtering target. Sputtering was performed using this target under the following conditions, an IGZO film was formed on a glass substrate, and the transmittance was measured.
(Sputtering conditions)
Gas: Argon, oxygen (10%)
Pressure: 0.45Pa
Power supply: DC
Input power: 150 W (1.9 W / cm ² )
Substrate temperature: room temperature Glass substrate: non-alkali glass (50 mm × 50 mm × 0.7 mmt)
IGZO film thickness: 200 nm
Next, the TFT element shown in FIG. 3 was produced by sputtering under the following conditions.
(IGZO film formation conditions)
Gas: Argon, oxygen (10%)
Pressure: 0.45Pa
Power supply: DC
Input power: 150 W (1.9 W / cm ² )
Substrate temperature: room temperature Substrate: n-Si substrate with SiO ₂ film (50 mm × 50 mm × 0.7 mmt)
IGZO film thickness: 50 nm
(Source and drain electrode formation conditions)
Electrode: Al
Gas: Argon (100%)
Pressure: 0.45Pa
Power supply: DC
Input power: 200 W (1.9 W / cm ² )
Substrate temperature: room temperature Film thickness: 50 nm (both source and drain)
This element was annealed in the atmosphere at 350 ° C. for 1 hour, and then the mobility was measured. In addition, the target surface after discharge was observed and it confirmed that the crack did not generate | occur | produce.

  Table 1 shows the measurement results of the identified species by the zirconia concentration, relative density, bending strength and X-ray diffraction (XRD) of the obtained sintered body, and the measurement results of the mobility of the obtained TFT element.

Comparative Example 1
In the same manner as in Example 1, three kinds of mixed powders (e) to (g) were produced by changing the addition amount of zirconium oxide. Next, in the same manner as in Example 1, powder preparation, molding, and firing were performed.

  After processing the obtained sintered body to 101.6 mmΦ × 6 mmt, it was bonded to an oxygen-free copper backing plate with indium solder to obtain a sputtering target. Using this target, an IGZO film was formed on a glass substrate under the same conditions as in Example 1, and the transmittance was measured.

  Next, a TFT element was produced by the same method as in Example 1, and after annealing this element in the atmosphere at 350 ° C. for 1 hour, the mobility was measured. In addition, the target surface after discharge was observed and it confirmed that the crack did not generate | occur | produce.

  Table 1 shows the measurement results of the identified species by the zirconia concentration, relative density, bending strength and X-ray diffraction (XRD) of the obtained sintered body, and the measurement results of the mobility of the obtained TFT element.

Comparative Example 2
In the same manner as in Example 1, four types of mixed powders (h) to (k) were produced by changing the addition amount of zirconium oxide. These powders were subjected to a dispersion treatment in a counter jet air type counter jet mill. Next, in order to improve the moldability of the powder, these dispersed powders are put in a polyethylene pot, and compacted by dry mixing for 10 hours with a rotating ball mill using a resin ball with a core of 15 mm in diameter. Went. Next, these powders were molded and fired in the same manner as in Example 1.

  After processing the obtained sintered body to 101.6 mmΦ × 6 mmt, it was bonded to an oxygen-free copper backing plate with indium solder to obtain a sputtering target. Using this target, an IGZO film was formed on a glass substrate under the same conditions as in Example 1, and the transmittance was measured.

  Next, a TFT element was produced by the same method as in Example 1, and after annealing this element in the atmosphere at 350 ° C. for 1 hour, the mobility was measured. In addition, the target surface after discharge was observed and it confirmed that the crack did not generate | occur | produce.

  Table 1 shows the measurement results of the identified species by the zirconia concentration, relative density, bending strength and X-ray diffraction (XRD) of the obtained sintered body, and the measurement results of the mobility of the obtained TFT element.

実施例２
実施例１（ｂ）の粉末を用い、平板形、および円筒形の種々の大きさの成形体を作製し、実施例１と同様の方法で焼成を行って焼結体を作製した。次に、これらの焼結体をターゲットとするために、平板形の焼結体は平面研削盤により、円筒形の焼結体は円筒研削盤により加工を実施した。加工後の焼結体に割れは認められなかった。得られた焼結体のサイズおよび割れ発生の有無を表２に示す。

Example 2
Using the powder of Example 1 (b), flat and cylindrical shaped bodies having various sizes were produced, and sintered in the same manner as in Example 1 to produce sintered bodies. Next, in order to target these sintered bodies, the flat plate-shaped sintered body was processed by a surface grinder, and the cylindrical sintered body was processed by a cylindrical grinder. No cracks were observed in the sintered body after processing. Table 2 shows the size of the obtained sintered body and the presence or absence of occurrence of cracks.

Of the produced sintered bodies, cylindrical sintered bodies were bonded to titanium backing tubes, respectively, and used as targets, then attached to a rotary cathode type sputtering apparatus, and sputtered to a remaining thickness of 1 mm under the following conditions. . Then, the target surface was observed and it confirmed that the crack did not generate | occur | produce.
(Sputtering conditions)
Gas: Argon, oxygen (10%)
Pressure: 0.3Pa
Power supply: DC
Input power: 500 W (5.3 W / cm ² )
Target rotation: 5rpm
Comparative Example 3
Using the powder of Comparative Example 2 (k), molded bodies of various sizes of a flat plate shape and a cylindrical shape were prepared, and fired by the same method as in Example 1 to prepare a sintered body. Next, in order to target these sintered bodies, the flat plate-shaped sintered body was processed by a surface grinder, and the cylindrical sintered body was processed by a cylindrical grinder. Table 2 shows the size of the obtained sintered body and the presence or absence of cracking due to processing.

  Among the produced sintered bodies, a cylindrical sintered body was bonded to a titanium backing tube to make a target, and then attached to a rotating cathode type sputtering apparatus and sputtered under the same conditions as in Example 2. . Then, the target surface was observed and it confirmed that the crack generate | occur | produced in the initial stage (remaining thickness 6mm) of sputtering.

1: n-Si substrate (gate)
2: SiO ₂ (300 nm)
3: Al (source 50 nm)
4: Al (drain 50 nm)
5: IGZO film (50 nm)
6: Interval (200 μm)

Claims (6)

An oxide sintered body containing In, Ga, and Zn, having a homologous crystal structure represented by InGaZnO ₄ , and containing zirconium in a weight ratio of 20 ppm or more and less than 100 ppm body. 2. The sintered body according to claim 1, wherein the relative density is 95% or more and the bending strength is 100 MPa or more. The sintered body according to claim 1 or 2, wherein the area of the target surface is 961 cm ² or more and the shape is a flat plate shape. The sintered body according to claim 1 or 2, wherein the area of the target surface is 257 cm ² or more and the shape is cylindrical. A sputtering target comprising the sintered body according to claim 1 as a target material. An oxide film obtained by sputtering the sputtering target according to claim 5.

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