JP5526904B2 - Conductive oxide sintered body and manufacturing method thereof - Google Patents

Description

  The present invention relates to a conductive oxide, and particularly relates to a conductive oxide preferable as a target for forming an oxide semiconductor film by sputtering.

  In a liquid crystal display device, a thin film EL (electroluminescence) display device, an organic EL display device, etc., an amorphous silicon film has conventionally been mainly used as a transparent conductive thin film for a channel layer of a thin film transistor (TFT) or a transparent electrode. I came.

  However, in recent years, as such a semiconductor film, an amorphous oxide semiconductor film containing In—Ga—Zn-based composite oxide (IGZO) as a main component has a higher carrier mobility than an amorphous silicon film. Has been attracting attention because of its advantage of being large (see, for example, Japanese Patent Application Laid-Open No. 2008-199005 of Patent Document 1). This Patent Document 1 discloses that an amorphous oxide semiconductor film is formed by a sputtering method using a target. And the target is the sintered compact of the oxide powder which shows electroconductivity.

JP 2008-199005 A

  When the oxide semiconductor film is formed by a sputtering method using the target disclosed in Patent Document 1 described above, a voltage is applied to the target of the oxide sintered body to generate plasma in the vicinity of the target surface. At this time, since the temperature of the target rises, the target is cooled with circulating water through a copper backing plate attached to the back surface of the target with a low melting point metal. Here, if the thermal conductivity of the target is low, the target is overheated and the film formation cannot proceed stably. Therefore, when the thermal conductivity of the target is low, generally the cooling efficiency is improved by reducing the thickness of the target as much as possible and increasing the thickness of the backing plate.

  On the other hand, in the vacuum chamber, the surface atoms of the target jump out by sputtering, and the target is consumed. If the amount of consumption of the target becomes excessive, the low melting point metal used for bonding to the backing plate is exposed, so the depth of use of the target is determined in consideration of the safety factor. Therefore, since the life of the target is reached when the determined use depth is reached, the thicker the target, the longer the life, which is preferable from the viewpoint of film formation productivity.

  However, in order to increase the target thickness, it is necessary to increase the thermal conductivity of the target. In addition, for example, a flat panel display manufacturing process using an amorphous oxide semiconductor film often includes a post-process for patterning by partially etching away the oxide semiconductor film. Increasing the etching rate is also desired from the viewpoint of productivity.

  Therefore, the object of the present invention is to increase the lifetime by increasing the thickness of the target by improving the thermal conductivity of the conductive oxide. Another object of the present invention is to make it possible to improve the etching rate of an oxide semiconductor film deposited by sputtering by using the target.

The conductive oxide sintered body according to the present invention is crystalline In ₂ Ga _{2 (1-m)} Zn _1-q O _7-p (0 ≦ m <1, 0 ≦ q <1, 0 ≦ p ≦ 3m + q). And crystalline Ga ₂ ZnO ₄ , the atomic concentration ratio of In is 1.5 or more and 4 or less and the atomic concentration ratio of Ga Is 0.5 or more and 3 or less, and the proportion of crystalline Ga ₂ ZnO _{4 in} the cross-sectional area of the conductive oxide sintered body is 20% or more and 60% or less. When the X-ray diffraction method is applied, the b peak having the diffraction angle 2θ of the peak a having the maximum diffraction intensity is in the range of 29.00 ° or more and 30.75 ° or less and has the second diffraction intensity. The diffraction angle 2θ is within the range of 33.00 ° or more and 36.00 ° or less, and with respect to the peak a Diffraction intensity ratio Ib / Ia of b peaks are characterized in that 0.1 to 1.0. In addition, it is preferable that c peak different from b peak is produced in the range where diffraction angle 2θ is 35.0 ° or more and 37.0 ° or less.

The conductive oxide may further include at least one element selected from N, Al, Si, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Sn, and Bi. . Conductive oxide sintered body according to the present invention is obtained preferably used in the target of the sputtering method, Ru obtained is preferably an oxide semiconductor film at its sputtering.

In the method for producing a conductive oxide sintered body according to the present invention, a first mixture containing zinc oxide powder and gallium oxide powder is prepared, and the first mixture is heated to a temperature of 800 ° C. or higher and lower than 1200 ° C. in calcinated to prepare a Ga ₂ ZnO ₄ particles, followed by a second mixture was prepared by mixing the Ga ₂ ZnO ₄ particles are mixed or pulverized with indium oxide particles, the second mixture It is preferable to include a step of producing a molded body and firing the molded body at a temperature of 1350 ° C. to 1375 ° C.

  According to the present invention as described above, by improving the thermal conductivity of the target of the conductive oxide, the thickness of the target can be increased and the life can be increased. Further, by using the conductive oxide target according to the present invention, the etching rate of the oxide semiconductor film deposited by sputtering can be improved.

Hereinafter, an embodiment of the present invention will be described in detail. As described above, the conductive oxide according to the present invention is crystalline In ₂ Ga _{2 (1-m)} Zn _1-q O _7-p (0 ≦ m <1, 0 ≦ q <1, 0 ≦ p ≦ 3m + q) and crystalline Ga ₂ ZnO _4, and when the powder X-ray diffraction method is applied, the diffraction angle 2θ of the a peak having the maximum diffraction intensity is in the range of 29.00 ° to 30.75 °. And the diffraction angle 2θ of the b peak having the second diffraction intensity is in the range of 33.00 ° to 36.00 °, and the diffraction intensity ratio Ib / Ia of the b peak to the a peak is 0. .1 or more and 1.0 or less. In such a conductive oxide, it was found that the thermal conductivity was improved as compared with a conventional amorphous In—Ga—Zn-based composite oxide. In addition, when an oxide semiconductor film was deposited by sputtering using the conductive oxide according to the present invention as a target and the etching rate of the film was measured, it was found that the etching rate was higher than that of a conventional oxide semiconductor film. .

By the way, crystalline In ₂ Ga ₂ ZnO ₇ and crystalline Ga ₂ ZnO ₄ are already known crystals. However, the conductive oxide according to the present invention is a sintered body that is modified by mixing these crystal powders under predetermined conditions.

More specifically, the sintered body according to the present invention has a crystalline In ₂ Ga _{2 (1-m)} Zn _1-q O _7-p (0 ≦ m <1, 0 ≦ q <1, 0 ≦ p ≦ 3m + q) and crystalline Ga ₂ ZnO ₄ , and preferably the thermal conductivity is higher when 0 <m and 0 <q. In addition, the etching rate of the oxide semiconductor film deposited by sputtering using such a conductive oxide as a target is increased. Note that crystalline In ₂ Ga _{2 (1-m)} Zn _1-q O _7-p is in a state in which Ga and Zn are deficient compared to the known In ₂ Ga ₂ ZnO ₇ crystal. Means. Due to this deficiency, when the stoichiometric ratio is considered, the oxygen atomic ratio may change and take a value smaller than “7” (that is, 0 <p).

In fact the crystalline _{In 2 Ga 2 (1-m} ) Zn 1-q O 7-p, it is difficult to determine directly the value of m and q. In the present embodiment, the composition of the entire sintered body is obtained by ICP (inductively coupled plasma) emission spectroscopy, and at the same time, the crystal phase is identified by X-ray diffraction, whereby crystalline In ₂ Ga _{2 (1-m)} Zn ₁₋ The presence of _q O _7-p is confirmed.

More specifically, the presence of In ₂ Ga ₂ ZnO ₇ and Ga ₂ ZnO ₄ by X-ray diffraction in spite of the atomic concentration ratio of In: Ga: Zn obtained by ICP analysis being 2: 2: 1. Is confirmed, In ₂ Ga _{2 (1-m)} Zn _1-q O _7-p (0 <m <1, 0 <q <1, where Ga and Zn are deficient in In ₂ Ga ₂ ZnO ₇ , 0 ≦ p ≦ 3m + q) and Ga ₂ ZnO ₄ are present.

In powder X-ray diffraction, crystalline In ₂ Ga ₂ ZnO ₇ and crystalline Ga ₂ ZnO ₄ have diffraction peaks at the same diffraction angle 2θ within a diffraction angle 2θ range of 29.00 ° to 30.75 °. Arise. On the other hand, crystalline In ₂ Ga ₂ ZnO ₇ produces a diffraction peak even when the diffraction angle 2θ is in the range of 33.00 ° to 36.00 °. Therefore, when crystalline In ₂ Ga ₂ ZnO ₇ and crystalline Ga ₂ ZnO ₄ coexist, the diffraction angle 2θ increases from 33.00 ° to 36.36 as the content of crystalline Ga ₂ ZnO ₄ increases. The intensity of the diffraction peak generated within the range of 00 ° or less is reduced.

In the conductive oxide containing crystalline In ₂ Ga _{2 (1-m)} Zn _1-q O _7-p and crystalline Ga ₂ ZnO ₄ , the present inventors have a diffraction angle 2θ of 29.00 ° or more. The a peak generated in the range of 30.75 ° or less has the maximum diffraction intensity, and the b peak generated in the range of the diffraction angle 2θ of 33.00 ° or more and 36.00 ° or less has the diffraction intensity of the second position When it has, it discovered that the heat conductivity of a conductive oxide became high.

Further, in the conductive oxide according to the present invention, a c peak different from the b peak is generated when the diffraction angle 2θ is in the range of 35.0 ° to 37.0 °. The c peak is due to the crystalline _Ga 2 ZnO _4, the presence of this crystalline _Ga 2 ZnO ₄ were found to affect the thermal conductivity. The proportion of crystalline Ga ₂ ZnO ₄ occupied in the cross-sectional area of the conductive oxide according to the present invention is 60% or less than 20 percent, it was found that preferred for increasing the thermal conductivity. In addition, it is more preferable that the cross-sectional area ratio of the crystalline Ga ₂ ZnO ₄ is 30% or more and 50% or less from the viewpoint of increasing the thermal conductivity.

That is, when the proportion of crystalline Ga ₂ ZnO _{4 in} the cross-sectional area of the conductive oxide is less than 20%, the thermal conductivity of the conductive oxide did not increase. The crystalline Ga ₂ ZnO ₄ is higher than the crystalline In ₂ Ga ₂ ZnO ₇ because the thermal conductivity increases when the conductive oxide is present in a volume fraction higher than that of the crystalline Ga ₂ ZnO _4. It is thought that it has high thermal conductivity. Alternatively, In ₂ Ga _{2 (1-m)} Zn _1-q O _7-p that satisfies 0 <m and 0 <q may have high thermal conductivity. On the other hand, when the proportion of crystalline Ga ₂ ZnO _{4 in} the cross-sectional area of the conductive oxide exceeds 60%, the surface roughness of the oxide semiconductor film deposited by sputtering using the conductive oxide as a target is low. It became too big and caused practical problems.

In addition, the cross-sectional area ratio of crystalline Ga ₂ ZnO ₄ can be obtained using an analytical scanning electron microscope. More specifically, the electrons (reflected electron image) reflected from the cross section resulting from the incident electron beam irradiated onto the cross section of the conductive oxide sample are observed. Then, by identifying the _Ga 2 ZnO ₄ regions by performing X-ray fluorescence analysis of the different regions of contrast, it is possible to measure the area ratio of _Ga 2 ZnO ₄ area occupied in the cross section.

  In the atomic concentration ratio of In, Ga, and Zn contained in the conductive oxide of the present invention, when the atomic concentration ratio of Zn is normalized to 1.0, the atomic concentration ratio of In is 1.5 or more and 4 or less. It is desirable that the Ga atom concentration ratio is in the range of 0.5 or more and 3 or less. When the atomic concentration ratio of In was less than 1.5 or the atomic ratio of Ga was larger than 3.0, the electric resistance of the conductive oxide was too high, and it was not suitable for practical use as a sputtering target. On the other hand, when the atomic concentration ratio of In in the conductive oxide is greater than 4 or the atomic concentration ratio of Ga is less than 0.5, the oxide semiconductor deposited by sputtering using the conductive oxide as a target The electrical characteristics of the film changed over time, and the oxide film was not suitable for practical use as an oxide semiconductor film in a display device. Here, the atomic concentration ratio of In, Ga, and Zn described above is normalized by the concentration value of Zn based on the concentration value (unit: atom%) measured by ICP emission analysis.

  The conductive oxide according to the present invention further includes at least one element selected from N, Al, Si, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Sn, and Bi. If included, it was preferable because the etching rate of the oxide semiconductor film deposited by sputtering the conductive oxide was increased.

  The conductive oxide according to the present invention can be preferably used as a target when an oxide semiconductor film is deposited by sputtering.

The conductive oxide according to the present invention is prepared by preparing a first mixture containing zinc oxide powder and gallium oxide powder, and calcining the first mixture at 800 ° C. or more and less than 1200 ° C. to obtain Ga ₂ ZnO ₄ particles. A second mixture is prepared by mixing and then pulverizing and mixing the Ga ₂ ZnO ₄ particles and indium oxide particles to produce a molded body of the second mixture, and the molded body Can be produced as a sintered body fired at a temperature of 1350 ° C. or higher and 1375 ° C. or lower. _Here, when sintering the molded body obtained by mixing Ga 2 ZnO ₄ particles and In2O3 particles, the ratio of _Ga 2 ZnO ₄ contained in a sintered body to be obtained varies with the sintering temperature, the lower the sintering temperature The ratio of Ga ₂ ZnO ₄ is increased. The oxide semiconductor film deposited by sputtering using the conductive oxide manufactured as described above as a target can be etched at high speed.

  Note that the atomic concentration of N, Al, Si, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Sn, or Bi additionally contained in the conductive oxide according to the present invention is deposited. Can be measured by SIMS (secondary ion mass spectrometry) on the membrane.

  As described above, the conductive oxide layer according to the present invention is crystalline, and the oxide can be preferably used as a sputtering target. And when depositing an oxide semiconductor film by sputtering using the conductive oxide of the present invention as a target, the thickness of the target can be increased by improving the thermal conductivity, and as a result, the target life can be lengthened and deposited. The etching rate of the formed oxide semiconductor film can be increased.

  Here, the term “sputtering target” means that a material for forming a film by sputtering is processed into a plate shape, or the plate-like material is attached to a backing plate (back plate for attaching a target material). It is a general term for things. The backing plate can be produced based on materials such as oxygen-free copper, steel, stainless steel, aluminum, aluminum alloy, molybdenum, and titanium.

  The target as described above can be produced from a size having a diameter of 1 cm to a size having a diameter exceeding 2 m like a sputtering target for a large LCD (liquid crystal display device). Etc. can be exemplified.

Below, the manufacturing method of the electroconductive oxide of this invention is demonstrated in detail. First, indium oxide (In ₂ O ₃ ) powder, gallium oxide (Ga ₂ O ₃ ) powder, zinc oxide (ZnO) powder, or the like can be used as the raw material powder for the conductive oxide. The purity of the raw material powder is preferably a high purity of 99.9% or more.

The prepared raw material powders of gallium oxide (Ga ₂ O ₃ ) and zinc oxide (ZnO) are mixed with each other to produce a first mixture. For mixing these raw material powders, either a dry method or a wet method may be used. Specifically, it can be mixed using a normal ball mill, a planetary ball mill, a bead mill or the like. For drying the mixture in the case of using a wet mixing method, a drying method such as natural drying or a spray dryer can be preferably used.

The obtained first mixture is calcined. The calcining temperature at this time is preferably 800 ° C. or higher and lower than 1200 ° C. Thereafter, the In ₂ O ₃ raw material powder is further mixed with the calcined first mixture to produce a second mixture. As the mixing method at this time, the same method as in the case of the first mixture can be employed.

  Thereafter, a molded body of the second mixture is produced, and the molded body is baked into a sintered body. In this case, the sintering temperature is preferably 1350 ° C. or higher and 1375 ° C. or lower.

  As the firing atmosphere, an air atmosphere, an oxygen atmosphere, a nitrogen-oxygen mixed atmosphere, or the like can be preferably used. In order to suppress evaporation of ZnO during firing, CIP (cold isostatic treatment), firing in a pressurized gas, hot press firing, HIP (hot isostatic treatment) sintering, etc. may be used. Good.

  By carrying out the steps as described above, the conductive oxide according to the present invention can be produced.

  In the following various examples according to the present invention, various conductive oxides were prepared as sputtering targets, and their thermal conductivities were measured. In addition, an oxide semiconductor film is deposited by sputtering using these conductive oxides as a target, wet etching using a mixed acid solution of phosphoric acid-acetic acid and dry etching using a gas are performed, and the oxide semiconductor film The etching rate was determined.

(Examples 1-4)
Step 1: Grinding and mixing raw material powder Ga ₂ O ₃ powder (purity 99.99%, BET specific surface area 11 m ² / g) and ZnO powder (purity 99.99%, BET specific surface area 4 m ² / g) Was pulverized and mixed for 3 hours to prepare a Ga ₂ O ₃ —ZnO mixture as the first mixture. In this case, the molar mixing ratio is Ga ₂ O ₃ : ZnO = 1: 1. Note that water was used as a dispersion medium in the pulverization and mixing. The first mixture after pulverization and mixing was dried with a spray dryer.

Step 2: Calcination The obtained first mixture is placed in an alumina crucible and subjected to calcination for 5 hours at a temperature of 900 ° C. in an air atmosphere, thus calcination consisting of crystalline Ga ₂ ZnO _4. A powder was obtained.

Step 3: Grinding and mixing with In ₂ O ₃ powder The obtained Ga ₂ ZnO ₄ calcined powder and In ₂ O ₃ powder (purity 99.99%, BET specific surface area 5 m ² / g) And pulverized and mixed for 6 hours, thereby producing a Ga ₂ ZnO ₄ —In ₂ O ₃ mixture as the _second mixture. The molar mixing ratio at this time is Ga ₂ ZnO ₄ : In ₂ O ₃ = 1: 1. In this case, water was also used as a dispersion medium for pulverization and mixing. The second mixture after pulverization and mixing was also dried with a spray dryer.

Step 4: Molding and Sintering The resulting second mixture, Ga ₂ ZnO ₄ —In ₂ O ₃ mixed powder, is molded by pressing, further pressure-molded by CIP, and a circle having a diameter of 100 mm and a thickness of about 9 mm. A plate-like molded body was obtained. The obtained molded body was fired at a predetermined temperature in an oxygen atmosphere for 5 hours, thereby obtaining a sintered body. In addition, each sintering temperature regarding Examples 1-4 at this time is collectively shown in Table 1.

Step 5: Measurement of thermal conductivity A sample having a diameter of 8 mm and a thickness of 2 mm was taken from the obtained sintered body, and the thermal conductivity was measured by a laser flash method. This measurement was performed at normal temperature in the atmosphere. Laser irradiation was performed from the sample surface, and the thermal conductivity was calculated from the temperature history of the back surface. The thermal conductivities obtained with respect to Examples 1 to 4 are normalized with the thermal conductivity of Comparative Example 1 described later as 1, and are collectively shown in Table 1.

  In Table 1, the atomic concentration ratio of In, Ga and Zn contained in the sintered conductive oxide is the atomic concentration of Zn based on the concentration value (unit: atom%) measured by ICP emission analysis. It is shown normalized as a ratio of 1.0.

Step 6: X-ray diffraction measurement Further, a sample was taken from a part of the obtained sintered body, and crystal analysis was performed by a powder X-ray diffraction method. As the X-ray, a Cu Kα ray was used, and a diffraction angle 2θ and a diffraction intensity I were measured.

Step 7: Preparation of Target The obtained sintered body was processed into a target having a diameter of 3 inches (76.2 mm) and a thickness of 5.0 mm.

Step 8: Film formation by sputtering method An oxide semiconductor film was deposited by a sputtering method using the obtained target. As the sputtering method, a DC (direct current) magnetron sputtering method was used. At this time, the plane of the target having a diameter of 3 inches was the sputtering surface.

First, a synthetic quartz glass substrate of 25 mm × 25 mm × 0.6 mm was placed as a film forming substrate on a water-cooled substrate holder in the film forming chamber of the sputtering apparatus. At this time, a partial region on the glass substrate was covered with a metal mask. The target was disposed to face the substrate, and the distance between the substrate and the target was 40 mm. Thereafter, the film forming chamber was evacuated to about 1 × 10 ⁻⁴ Pa, and the target was pre-sputtered. Specifically, Ar gas is introduced into the deposition chamber up to a pressure of 1 Pa with a shutter between the substrate and the target, and 30 W DC power is applied to cause sputtering discharge, thereby causing the target surface Cleaning (pre-sputtering) was performed for 10 minutes.

  Thereafter, Ar containing oxygen gas at a flow rate ratio of 0.5% introduced soot into the film formation chamber to a predetermined pressure, and film formation was performed for 1 hour at a sputtering power of 50 W. Note that no bias voltage was applied to the substrate holder, and the substrate holder was only water-cooled. When the substrate was taken out of the deposition chamber after film formation, an In—Ga—Zn—O film was formed only in a region that was not covered with the metal mask on the substrate. And it was deposited by measuring the step between the region covered with the metal mask on the substrate where the film was not formed and the region where the film was formed on the substrate with a stylus type surface roughness meter. The film thickness was determined.

Step 9: Etching Thereafter, an aqueous etching solution of phosphoric acid: acetic acid: water = 4: 1: 100 was prepared, and the quartz glass substrate on which the In—Ga—Zn—O film was formed was immersed in the etching solution. At this time, the etching solution was heated to 50 ° C. in the hot bath. The immersion time was set to 2 minutes, and the thickness of the film remaining without being etched during that time was measured with a stylus type surface roughness meter. The difference between the film thickness immediately after film formation and the thickness of the film remaining after etching was divided by the etching time to determine the etching rate. The etching rates in Examples 1 to 4 are shown in Table 1, normalized by setting the etching rate of Comparative Example 1 to 1.

(Example 5)
Also in the fifth embodiment, the above-described steps 1 and 2 are the same as those in the first to fourth embodiments. However, the fifth embodiment differs from the first to fourth embodiments in that steps 3 and 4 are partially changed. That is, in Example 5, the above-mentioned steps 3 and 4 were partially changed as the following steps 3a and 4a.

Step 3a: Grinding and mixing with In ₂ O ₃ powder and GaN powder Ga ₂ ZnO ₄ powder obtained by calcination of Step ₂ and In ₂ O ₃ (purity 99.99%, BET specific surface area 5 m ² / g) The powder and GaN (purity 99.99%, BET specific surface area 2 m ² / g) were pulverized and mixed for 6 hours using a ball mill apparatus. The molar mixing ratio at this time was Ga ₂ ZnO ₄ : In ₂ O ₃ : GaN = 1: 1: 0.05. Water was used as the dispersion medium, and the mixture after pulverization and mixing was dried with a spray dryer.

Step 4a: Molding and Sintering Next, the obtained Ga ₂ ZnO ₄ —In ₂ O ₃ —GaN mixed powder is molded by pressing, further pressure-molded by CIP, and a circle having a diameter of 100 mm and a thickness of about 9 mm. A plate-like molded body was obtained. The obtained molded body was made into a sintered body by firing at 1375 ° C. for 5 hours in an N ₂ atmosphere of 1 atm. The obtained sintered body contracted to a diameter of 80 mm and a thickness of about 7 mm.

  The conditions relating to Steps 5 to 9 in Example 5 thereafter are the same as those in Examples 1 to 4, and the results relating to Example 5 are also shown in Table 1.

(Examples 6 to 18)
The targets in Examples 6 to 18 were basically manufactured in the same manner as the targets in Examples 1 to 4, but added in the pulverization and mixing of Ga ₂ ZnO ₄ powder and In ₂ O ₃ powder in Step 3. Oxide powder containing elements (Al ₂ O ₃ , SiO ₂ , TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , ZrO ₂ , Nb ₂ O ₃ , MoO ₂ , HfO ₂ , Ta ₂ O ₃ , WO ₃ , SnO ₂ , Bi ₂ O ₃ ) were added and pulverized and mixed. When the oxide of the additive element is Al ₂ O ₃ , Cr ₂ O ₃ , Nb ₂ O ₃ , Ta ₂ O ₃ , or Bi ₂ O ₃ , the molar mixing ratio is Ga ₂ ZnO ₄ : In ₂ O ₃ : The oxide of the additive element is 1: 1: (0.1 or less and 0.01 or more). When the oxide of the additive element is SiO ₂ , TiO ₂ , ZrO ₂ , MoO ₂ , HfO ₂ , WO ₃ , or SnO ₂ , the molar mixing ratio is Ga ₂ ZnO ₄ : In ₂ O ₃ : additive element. Of oxide = 1: 1: (0.2 or less and 0.02 or more). The results regarding Examples 6 to 18 as described above are also summarized in Table 1.

(Example 19)
The target in Example 19 was basically manufactured in the same manner as the target in Examples 1 to 4, but Ga ₂ ZnO obtained by calcination in pulverization and mixing with In ₂ O ₃ powder in Step 3 was used. _The only difference was that the _four powders were ground and mixed with In ₂ O ₃ powder and InGaO ₃ powder. Mol mixing ratio at this _{time, Ga 2 ZnO 4: In 2} O 3: InGaO 3 = 1: 1: 1. The results for Example 19 are also shown in Table 1. The atomic concentration of the additive element was determined as the number of atoms per 1 cm ³ (atoms / cc) by analyzing the film deposited by sputtering with SIMS.

(Example 20)
The target in Example 20 was basically manufactured in the same manner as the target in Examples 1 to 4, but Ga ₂ ZnO ₄ obtained by calcination in pulverization and mixing with In ₂ O ₃ powder in Step 3. The only difference was that the powder was ground and mixed with In ₂ O ₃ powder and In ₂ Zn ₄ O ₇ powder. Mol mixing ratio at this _{time, Ga 2 ZnO 4: In 2} O 3: In 2 Zn 4 O 7 = 1: 4: 1. The results for Example 20 are also shown in Table 1.

(Comparative Example 1)
In Comparative Example 1 corresponding to a conventional conductive oxide, the manufacturing method was slightly changed. Specifically, it was manufactured through the following steps 1b to 3b.

Step 1b: Grinding and mixing of raw material powder In this step 1b, in comparison with Step 1 described above, In ₂ O ₃ powder (purity 99.99%, BET specific surface area 5 m ² / g) is Ga ₂ O ₃ powder and The only difference was that it was added to the ZnO powder and ground and mixed.

Step 2b: Calcination The mixed powder obtained in Step 1b was calcined under the same conditions as in Step 2 described above, whereby a calcined powder was obtained.

Step 3b: Molding and Sintering The calcined powder obtained in Step 2b was molded by uniaxial pressure molding to obtain a disk-shaped molded body having a diameter of 100 mm and a thickness of about 9 mm. This molded body was fired at 1500 ° C. for 5 hours in an oxygen atmosphere, whereby an In ₂ Ga ₂ ZnO ₇ sintered body was obtained.

  Thereafter, also in the sintered body obtained in Comparative Example 1, the thermal conductivity was measured in the same manner as in Step 5 described above, the X-ray measurement was performed in the same manner as in Step 6, and the target was measured in the same manner as in Step 7. It was fabricated and sputter deposited as in step 8 and the etch rate was measured as in step 9. These results in Comparative Example 1 are also summarized in Table 1. As can be seen from Table 1, the conductive oxide according to Comparative Example 1 was amorphous, and no clear diffraction peak appeared in the X-ray measurement.

(Comparative Example 2)
The conductive oxide target of Comparative Example 2 was basically manufactured in the same manner as the targets of Examples 1 to 4, but only that the temperature during sintering of the conductive oxide was set high at 1390 ° C. Was different. The results for Comparative Example 2 are also shown in Table 1.

  As is clear from the results summarized in Table 1 as described above, the targets of the conductive oxides according to Examples 1 to 20 satisfying the conditions of the present invention are higher in thermal conductivity than Comparative Examples 1 and 2. It can be seen that the etching rate of the deposited film can be improved.

  As described above, the conductive oxide according to the present invention can be preferably used as a target for sputtering film formation, and can have a long lifetime by improving the thermal conductivity of the target. Sputtering using the target is also possible. It is also possible to improve the etching rate of the deposited oxide semiconductor film.

Claims (5)

Conductivity and a crystalline _{In 2 Ga 2 (1-m} ) Zn 1-q O 7-p (0 ≦ m <1,0 ≦ q <1,0 ≦ p ≦ 3m + q) and a crystalline _Ga 2 ZnO ₄ An oxide sintered body,
In the conductive oxide sintered body, when the atomic concentration ratio of Zn is normalized to 1, the atomic concentration ratio of In is 1.5 or more and 4 or less, and the atomic concentration ratio of Ga is 0.5 or more and 3 or less. And
The ratio of the crystalline Ga ₂ ZnO ₄ to the cross-sectional area of the conductive oxide sintered body is 20% or more and 60% or less,
When the powder X-ray diffraction method is applied to the conductive oxide sintered body, the diffraction angle 2θ of the a peak having the maximum diffraction intensity is in the range of 29.00 ° to 30.75 °, and The diffraction angle 2θ of the b peak having the second diffraction intensity is in the range of 33.00 ° to 36.00 °, and the diffraction intensity ratio Ib / Ia of the b peak to the a peak is 0.1. A conductive oxide sintered body characterized by being 1.0 or more and 1.0 or less.   2. The conductive oxide sintered body according to claim 1, wherein a c peak different from the b peak is produced within a diffraction angle 2θ of 35.0 ° or more and 37.0 ° or less. N, Al, Si, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Sn, and claim 1 or claim characterized in that it further comprises at least one element selected from Bi Item 3. The conductive oxide sintered body according to Item 2. Conductive oxide sintered body as claimed in any one of claims 3, characterized in that used for the target of the sputtering method. It is any method for producing a conductive oxide sintered body according to one of claims 1 to 4, a first mixture comprising a zinc oxide powder and gallium oxide powders were prepared, wherein by the first mixture is calcined at a temperature of less than 1200 ° C. 800 ° C. or higher to prepare a _Ga 2 ZnO ₄ particles, mixed and thereafter mixing or grinding with indium oxide particles and said _Ga 2 ZnO ₄ particles The manufacturing method characterized by including the process of preparing the 2nd mixture, producing the molded object of the said 2nd mixture, and sintering the said molded object at the temperature of 1350 degreeC or more and 1375 degrees C or less.