JP2008195567A - Zinc oxide based sintered compact and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a zinc oxide based sintered compact and a method of manufacturing the same which can suppress the occurrence of particles and abnormal discharge in a step for film-depositing a zinc oxide based transparent thin film. <P>SOLUTION: The zinc oxide based sintered compact having an element ratio P/Zn of phosphorus to zinc of 0.006-0.06, a sintering density of ≥5.4 g/cm<SP>3</SP>and the diameter of a phosphorus compound of ≤5 μm, is obtained by mixing and pulverizing a powdery raw material comprising zinc pyrophosphate or zinc phosphate hydrate and zinc oxide and having 3-20 m<SP>2</SP>/g specific surface area, subjecting the pulverized powdery raw material to rapid drying and granulation, forming the resultant granulated material, increasing the temperature of the resultant formed body at 0.5-10 °C/min in the range of 600-1,000°C and firing at 1,000-1,200°C for 10-30 hr. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a zinc oxide-based sintered thin film used for forming a zinc oxide-based transparent thin film, particularly a zinc oxide-based transparent thin film doped with phosphorus, and a method for producing the same.

  Zinc oxide has been used as a material for gas sensors, phosphors, varistors, piezoelectric materials, and transparent electrodes since it is not toxic, has abundant resources, and is inexpensive.

In addition, since zinc oxide is a direct transition type and has a wide band gap energy of 3.2 eV, it has a high transmittance in the visible light region. By adding Al ₂ O ₃ or Ga ₂ O ₃ , a specific resistance value is obtained. Is on the order of 10 ⁻⁴ Ω · cm. For this reason, it is widely used as a material for solar cells.

  In addition, zinc oxide is expected as a material for LED semiconductors because of its wide band gap, high exciton energy, and low cost. Furthermore, since it has higher mobility than a-Si (amorphous silicon), it is also expected as a material for transparent semiconductors.

When used as a semiconductor element such as an LED or TFT, p-type ZnO is required, and addition of nitrogen, addition of phosphorus, and the like have been studied. Patent Document 1 discloses that a p-type semiconductor having a high carrier concentration is produced by a molecular beam epitaxy (MBE) method using a compound such as Zn ₃ P ₂ . However, the Zn ₃ P ₂ compound is toxic to be used as a rodenticide and generates toxic PH ₃ (phosphine) gas by thermal decomposition, which is not preferable for production.

  As a means for forming a zinc oxide-based transparent thin film used as a semiconductor material, a sputtering method and a pulsed laser deposition (PLD) method can be used in addition to the MBE method. In the sputtering method or the PLD method, a sintered body is used in the production of a thin film, but the dopant is supplied from a vapor deposition source different from the zinc oxide sintered body, and a special apparatus is used. In order to use a general sputtering apparatus, it is necessary to add a dopant to the zinc oxide sintered body. However, if an insulating compound is unevenly distributed in the sintered body, abnormal discharge occurs. Or the composition distribution in the film becomes non-uniform. Also, if the sintered density is low, many particles are generated, causing abnormal discharge. If abnormal discharge frequently occurs, the plasma discharge state becomes unstable, and stable film formation is not performed, which adversely affects the film characteristics. In addition, if the composition distribution in the film becomes non-uniform, there is a problem that desired characteristics cannot be obtained.

Therefore, there has been a demand for zinc oxide-based sintered bodies doped with phosphorus, in which an insulating compound is not unevenly distributed, but so far, a sufficient one capable of suppressing the occurrence of abnormal discharge is obtained. It was not done.
JP 2002-94114 A

  An object of this invention is to provide the zinc oxide type sintered compact which can suppress generation | occurrence | production of abnormal discharge in the film-forming process of a zinc oxide type transparent thin film, and its manufacturing method.

The zinc oxide-based sintered body according to the present invention has an element ratio P / Zn between phosphorus and zinc of 0.006 to 0.06, a sintered density of 5.4 g / cm ³ or more, The diameter is 5 μm or less.

In order to produce the zinc oxide-based sintered body according to the present invention, the raw material powder having a specific surface area of 3 to ²⁰ m ² / g composed of zinc pyrophosphate or zinc phosphate hydrate and zinc oxide was pulverized while being mixed. Then, after carrying out rapid dry granulation and shape | molding the obtained granulated material, the temperature range of 600-1000 degreeC is heated at 0.5-10 degreeC / min, and the obtained molded object is 1000-1000. Bake at 1200 ° C. for 10-30 hours.

  The firing is preferably performed by a normal pressure sintering method. In this case, it is preferable to introduce oxygen gas at a flow rate of 2 to 20 L / min in the temperature raising step in the temperature range of 600 to 1000 ° C.

  When the zinc oxide-based sintered body according to the present invention is used, since the occurrence of abnormal discharge in the sintered body is small during film formation, it is efficiently, inexpensively, energy-saving, and doped with high-quality phosphorus. A zinc oxide-based transparent thin film can be formed.

[Sintered body]
The zinc oxide-based sintered body according to the present invention has an element ratio P / Zn between phosphorus and zinc of 0.006 to 0.06, a sintered density of 5.4 g / cm ³ or more, and a phosphorus compound. The distribution is 5 μm or less, that is, the diameter of the phosphorus compound is 5 μm or less.

  In order to solve the above-mentioned problems, the present inventor conducted analysis on a zinc oxide-based sintered body used for forming a zinc oxide-based transparent thin film doped with phosphorus, and as a result of earnest examination, In order to make the sintered body usable in the sputtering method and the PLD method, it has been found that the following matters are required.

(1) The sintered density is 5.4 g / cm ³ or more,
(2) The phosphorus compound has a diameter of 5 μm or less.

(Element ratio of phosphorus and zinc)
The element ratio P / Zn of phosphorus and zinc in the zinc oxide-based sintered body according to the present invention is 0.006 to 0.06. If P / Zn is less than 0.006, the effect of phosphorus addition cannot be obtained, while if it exceeds 0.06, the sintered density is lowered.

In the sintered body, phosphorus exists as a phosphorus compound. Specifically, it exists as a phosphozinc oxide such as Zn ₂ P ₂ O ₇ .

(Sintering density)
The sintered density of the zinc oxide-based sintered body according to the present invention is 5.4 g / cm ³ or more. The higher the sintered density, the less the generation of oxide powder called particles during film formation. These particles are lower oxides and have an adverse effect on the transmittance of the thin film. The sintered density is the weight per unit volume of the sintered body, and is determined from the weight and dimensions after processing the sintered body.

(Phosphorus compound)
The diameter of the phosphorus compound in the zinc oxide based sintered body according to the present invention is 5 μm or less. If a coarse phosphorous compound having a diameter of more than 5 μm, particularly having a diameter of about 10 to 100 μm, is present in the sintered body, it causes abnormal discharge during film formation. In particular, in order to suppress the occurrence of abnormal discharge during film formation, the diameter of the phosphorus compound is preferably less than 1 μm.

  The diameter of the phosphorus compound (the size of the phosphorus compound) can be confirmed by SEM observation, but the cross section of a plurality of arbitrary parts of the zinc oxide-based sintered body was mirror-polished and then an electron beam microanalyzer (EPMA) was used. It is also possible to measure the concentration distribution of phosphorus by EPMA surface analysis and obtain the maximum length of a region having a high phosphorus concentration.

  By providing the conditions regarding the sintering density and the diameter of the phosphorus compound, it is possible to obtain a film-forming sintered body with less generation of particles and abnormal discharge over the long term.

[Method for producing sintered body]
Next, each factor affecting the zinc oxide-based sintered body in the manufacturing process of the zinc oxide-based sintered body of the present invention will be described below.

(Raw material powder)
As raw materials for obtaining the zinc oxide sintered body of the present invention, zinc oxide and zinc pyrophosphate or zinc phosphate hydrate are used. In order to add phosphorus, it is possible to use Zn ₃ P ₂ and P ₂ O _{5 in} addition to the above compounds, but Zn ₃ P ₂ has a problem of toxicity as described above. Further, P ₂ O ₅ has a strong hygroscopic property and has a problem that it becomes a strong acid when made into a slurry. On the other hand, zinc pyrophosphate or zinc phosphate hydrate does not have such a problem.

In the present invention, a raw material powder having a specific surface area of 3 to ²⁰ m ² / g is used. If the specific surface area of any of the raw material powders is less than 3 m ² / g, the packing density of the raw material powders becomes high, but the particle size is large and the surface energy is low, so the sintering driving force is reduced and the resulting oxidation The sintered density of the zinc-based sintered body cannot be as high as 5.4 g / cm ³ or more. On the other hand, when it is larger than 20 m ² / g, the packing density of the raw material powder becomes low, and the voids generated there cause a reduction in density of the obtained zinc oxide-based sintered body. In particular, in order to suppress the occurrence of abnormal discharge during film formation, it is preferable to select 5 to 15 m ² / g for the specific surface area of the raw material powder.

(mixture)
First, the raw material powder is mixed. For mixing, a wet or dry ball mill, vibration mill, bead mill, or the like can be used. In order to obtain uniform and fine crystal grains and vacancies, the bead mill mixing method is most preferable because it provides a high efficiency of crushing aggregates and a good dispersion state of additives in a short time.

  The time for pulverization and mixing by the bead mill varies depending on the size of the apparatus and the amount of slurry to be processed, but it is preferable to adjust the particle size distribution in the slurry to be 1 μm or less and uniform.

  When the treatment time is short, since the raw material powder cannot be uniformly pulverized and mixed, voids are generated in the obtained zinc oxide-based sintered body, which may lead to a decrease in relative density. On the other hand, even if the particle size distribution in the slurry is adjusted to 1 μm or less, if the grinding and mixing are performed for a long time, fine particles are present, the packing density of the raw material powder is lowered, and the resulting zinc oxide-based firing is obtained. It tends to cause a decrease in the relative density of the aggregate. Since this processing time is determined based on various conditions such as the mixing method and the particle size of the raw material powder, it is necessary to obtain optimum conditions in advance.

  Further, when mixing, an arbitrary amount of binder is added and mixed at the same time. As the binder, polyvinyl alcohol, vinyl acetate, or the like can be used.

  Thus, a raw material powder slurry is obtained.

(Rapid drying granulation)
Next, granulated powder is obtained from the raw material powder slurry. In the present invention, rapid drying granulation is performed during granulation. Spray dryers are widely used as devices for rapid drying granulation. Specific drying conditions are determined by various conditions such as the slurry concentration of the raw material powder slurry, the temperature of hot air used for drying, and the amount of air flow. Therefore, it is necessary to obtain optimum conditions in advance.

  In natural drying, since the sedimentation speed varies depending on the specific gravity difference of the raw material powder, separation of zinc pyrophosphate or zinc phosphate hydrate from zinc oxide occurs, and uniform granulated powder cannot be obtained. When a sintered body is produced using the non-uniform granulated powder, a coarse phosphorus compound phase, that is, a phosphorus compound having a diameter of about 10 to 100 μm is generated, which causes abnormal discharge during film formation. .

(Molding)
The granulated powder is molded at a pressure of 98 MPa (1 ton / cm ² ) or higher by a die press or cold isostatic press (CIP) to obtain a molded body. In particular, it is preferable to mold at a pressure of 196 MPa or more using CIP.

(Baking)
As a sintering method for obtaining the zinc oxide-based sintered body of the present invention, a pressure sintering method such as hot pressing, oxygen pressurization, hot isostatic pressing, etc. can be employed in addition to the atmospheric pressure sintering method. it can. However, it is preferable to employ a normal pressure sintering method from the viewpoints of reducing manufacturing costs, possibility of mass production, and easy production of large sintered bodies.

The firing temperature is 1000 to 1200 ° C. If the firing temperature is less than 1000 ° C., the sintered density cannot be made 5.4 g / cm ³ or more, which causes generation of particles during film formation. On the other hand, when the firing temperature exceeds 1200 ° C., the reaction between zinc oxide and the hearth plate occurs, and the hearth plate becomes brittle. At the same time, the sintered density is lowered by the sublimation of zinc oxide. In particular, the firing temperature is preferably 1050 to 1150 ° C.

The firing time is 10 to 30 hours. When the firing time is shorter than 10 hours, the compact is not sufficiently sintered, and the sintered density is less than 5.4 g / cm ³ . On the other hand, if the firing time exceeds 30 hours, the reaction between zinc oxide and the hearth plate occurs, and the hearth plate becomes brittle, which is not preferable for production. In particular, the firing time is preferably 20 to 30 hours.

  Furthermore, the temperature increase rate at the time of baking needs to be 0.5-10 degreeC / min in the temperature range of 600-1000 degreeC. The temperature range of 600 to 1000 ° C. is the range in which the sintering proceeds most. When the rate of temperature increase in this temperature range is slower than 0.5 ° C./min, the crystal grain growth becomes remarkable and the density is increased. Cannot be achieved. On the other hand, when the rate of temperature rise is faster than 10 ° C./min, the heat uniformity in the sintering furnace is lowered, and as a result, the amount of shrinkage during the sintering is distributed, which may break the sintered body. In particular, the rate of temperature increase is preferably 2 ° C./min or more.

  In the case of using the atmospheric sintering method for firing, it is preferable to introduce oxygen during the temperature rising process from 600 ° C. to 1000 ° C. in order to further increase the sintering density. The oxygen flow rate when introducing oxygen is preferably 2 to 20 L / min. Since zinc oxide powder is easy to evaporate, if the oxygen flow rate during sintering is less than 2 L / min, the effect of suppressing the evaporation of metal oxide (increase in density) is diminished and the sintering density is lowered. On the other hand, if it exceeds 20 L / min, the inside of the sintering furnace is cooled by the flow rate, and soaking is reduced.

By controlling the various conditions in the production process of the sintered body as described above, a zinc oxide-based sintered body having a sintered density of 5.4 g / cm ³ and a phosphorus compound diameter of 5 μm or less is obtained. be able to. When such a zinc oxide-based sintered body is processed into a predetermined shape and used for film formation by sputtering or PLD, a zinc oxide-based transparent thin film can be obtained without causing particles or abnormal discharge during film formation.

[Example 1]
A zinc oxide powder having a specific surface area of 10.5 m ² / g and a zinc phosphate hydrate powder having a specific surface area of 13.2 m ² / g were adjusted so that the element ratio P / Zn of phosphorus and zinc was 0.01. The mixture was added, 1% by mass of polyvinyl alcohol was added as a binder, and the mixture was pulverized by mixing with a bead mill until the particle size of the raw material powder became 1 μm or less, thereby obtaining a slurry. The mixing time was 1 hour.

  The specific surface area was measured with a fully automatic BET specific surface area measuring device (Macsorb HM Model-1208, manufactured by Mountec Co., Ltd.).

The obtained slurry was taken out, and subjected to rapid drying granulation using a spray dryer under the conditions of a slurry supply rate of 140 ml / min, a hot air temperature of 140 ° C., and a hot air amount of 8 Nm ³ / min to obtain a granulated product.

The obtained granulated product was molded with a cold isostatic press at a pressure of 294 MPa (3 ton / cm ² ) to obtain a disk-shaped molded body having a diameter of 100 mm and a thickness of 8 mm.

  Next, the obtained molded body was heated in the atmosphere at a rate of 0.5 ° C./min up to 600 ° C., and oxygen gas was introduced at 10 L / min, and a temperature range of 600 to 1100 ° C. Then, the temperature was increased at a rate of 3 ° C./min. Thereafter, holding at 1100 ° C. for 20 hours was performed to obtain a sintered body. The sintered density of the obtained sintered body was calculated from the mass and dimensions.

  Thereafter, a part of the sintered body was cut, the cut portion was mirror-polished, and the diameter of the phosphorus compound was measured by EPMA surface analysis. As a result, no phosphorus compound exceeding 1 μm was present. The phosphorus compound diameter was determined by measuring the concentration distribution of phosphorus in a 300 μm square region randomly selected from a mirror-polished sample by EPMA surface analysis, and determining the maximum length of the region with a high phosphorus concentration as the diameter of the phosphorus compound. As measured.

  The obtained sintered body was processed into a disk shape having a diameter of 75 mm and a thickness of 6 mm to produce a sputtering target. Using the obtained sputtering target, the number of abnormal discharges during DC magnetron sputtering was examined. The sputtering conditions were fixed at an input power of 200 W and an Ar gas pressure of 0.3 Pa. The number of abnormal discharges generated per 10 minutes after the lapse of 10 hours from the start of the experiment was measured. The obtained results are shown in Table 1.

[Example 2]
A sintered body was obtained in the same manner as in Example 1 except that a zinc oxide powder having a specific surface area of 3.8 m ² / g and a zinc phosphate hydrate powder having a specific surface area of 3.5 m ² / g were used. Produced.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Example 3]
A sintered body was obtained in the same manner as in Example 1 except that a zinc oxide powder having a specific surface area of 18.5 m ² / g and a zinc phosphate hydrate powder having a specific surface area of 19.1 m ² / g were used. Produced.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Example 4]
A sintered body was produced in the same manner as in Example 1 except that the sintering was performed at 1000 ° C. for 10 hours.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Example 5]
A sintered body was produced in the same manner as in Example 1 except that the sintering was performed at 1200 ° C. for 30 hours.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Example 6]
A sintered body was produced in the same manner as in Example 1 except that oxygen gas was introduced at 20 L / min during sintering.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Example 7]
A sintered body was produced in the same manner as in Example 1 except that oxygen gas was introduced at 2 L / min during sintering.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Example 8]
A sintered body was produced in the same manner as in Example 1 except that the temperature was raised at 0.5 ° C./min in the temperature range of 600 to 1100 ° C. during sintering.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Example 9]
A sintered body was produced in the same manner as in Example 1 except that the temperature was raised at 10 ° C./min in the temperature range of 600 to 1100 ° C. during sintering.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Comparative Example 1]
A sintered body was prepared in the same manner as in Example 1 except that a zinc oxide powder having a specific surface area of 2.5 m ² / g and a zinc phosphate hydrate powder having a specific surface area of 2.0 m ² / g were used. Produced. When the particle size distribution of the slurry was measured, particles having a maximum size of 10 μm were observed even though mixing by the bead mill was performed for the same pulverization time as in Example 1. Obtained sintered density of the sintered body is 5.31 g / cm ^3, below the 5.4 g / cm ^3.

  About the magnitude | size of the phosphorus compound measured similarly to Example 1, the phosphorus compound of a maximum of 10 micrometers existed. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Comparative Example 2]
A sintered body was obtained in the same manner as in Example 1, except that a zinc oxide powder having a specific surface area of 21.5 m ² / g and a zinc phosphate hydrate powder having a specific surface area of 20.8 m ² / g were used. Produced. Obtained sintered density of the sintered body is 5.28 g / cm ^3, below the 5.4 g / cm ^3.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, no phosphorus compound exceeding 5 μm was present. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Comparative Example 3]
A sintered body was produced in the same manner as in Example 1 except that the sintering was carried out at 1000 ° C. for 5 hours. Obtained sintered density of the sintered body is 5.29 g / cm ^3, below the 5.4 g / cm ^3.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, no phosphorus compound exceeding 5 μm was present. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Comparative Example 4]
A sintered body was produced in the same manner as in Example 1 except that the sintering was performed at 1200 ° C. for 35 hours. Obtained sintered density of the sintered body is 5.33 g / cm ^3, below the 5.4 g / cm ^3.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Comparative Example 5]
A sintered body was produced in the same manner as in Example 1 except that the temperature was raised at 0.3 ° C./min in the temperature range of 600 to 1100 ° C. during sintering. Obtained sintered density of the sintered body is 5.32 g / cm ^3, below the 5.4 g / cm ^3.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, there was no phosphorus compound exceeding 1 μm. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Comparative Example 6]
A sintered body was produced in the same manner as in Example 1 except that the slurry produced in the same manner as in Example 1 was used, naturally dried in a high-temperature tank, and pulverized to 300 μm or less to obtain a granulated product. . Obtained sintered density of the sintered body is 5.29 g / cm ^3, below the 5.4 g / cm ^3.

  Regarding the size of the phosphorus compound measured in the same manner as in Example 1, a maximum of 20 μm of phosphorus compound was present. Moreover, about the obtained sintered compact, the sputtering target was produced similarly to Example 1, and the frequency | count of abnormal discharge in DC magnetron sputtering was investigated. The obtained results are shown in Table 1.

[Comparative Example 7]
When sintering was performed in the same manner as in Example 1 except that the temperature was raised at 12 ° C./min in the temperature range of 600 to 1100 ° C., sintering cracks occurred.

In Examples 1 to 9, as can be seen from Table 1, the sintered density of the obtained zinc oxide-based sintered body is 5.4 g / cm ³ or more, and the obtained sintered body has a diameter of 1 μm. There is no phosphorus compound exceeding.

  On the other hand, in Comparative Example 1 and Comparative Example 2, the specific surface areas of the zinc oxide powder and the zinc phosphate hydrate powder are outside the scope of the present invention. In Comparative Example 1, the sintered density of the sintered body was low, phosphorus compounds were also observed, and abnormal discharge occurred. Also in Comparative Example 2, the requirements for the sintered density of the sintered body were not satisfied, and abnormal discharge occurred.

  In Comparative Examples 3 to 5, the sintering conditions were outside the scope of the present invention, the requirements for the sintered density of the sintered body were not satisfied, and abnormal discharge occurred.

  In Comparative Example 6, since granulation was performed by natural drying, the requirements for the sintered density of the sintered body were not satisfied, and a phosphorus compound was also present. Therefore, abnormal discharge occurred.

  Moreover, in Comparative Example 7, the temperature rise was too fast, sintering cracks occurred, and a sputtering target could not be produced.

Claims (3)

Oxidation characterized in that the element ratio P / Zn of phosphorus and zinc is 0.006 to 0.06, the sintered density is 5.4 g / cm ³ or more, and the diameter of the phosphorus compound is 5 μm or less. Zinc-based sintered body. After pulverizing the raw material powder composed of zinc pyrophosphate or zinc phosphate hydrate and zinc oxide with a specific surface area of 3 to ²⁰ m ² / g, rapid drying granulation is performed, and the resulting granulated product is molded. The obtained compact is heated at a temperature range of 600 to 1000 ° C. at 0.5 to 10 ° C./min and fired at 1000 to 1200 ° C. for 10 to 30 hours. A method for producing a sintered body.   3. The oxygen gas is introduced at a flow rate of 2 to 20 L / min in the temperature raising step in the temperature range of 600 to 1000 ° C., wherein the firing is performed by a normal pressure sintering method. Of manufacturing a zinc oxide-based sintered body.