KR20080031873A - Process for producing izo sputtering target - Google Patents

Abstract

A process for IZO sputtering target production in which the number of steps can be reduced while maintaining properties required of an IZO sputtering target to thereby attain an improvement in productivity and a reduction in production cost. Also provided is the production process in which a reduced sintering temperature can be used to thereby attain an improvement in productivity and a reduction in production cost. The process for producing an IZO sputtering target is characterized by comprising: a mixing/pulverization step in which either an indium oxide powder and zinc oxide power each having specific properties or a raw powder comprising these powders as major components is mixed and pulverized to obtain a fine powder; a molding step in which the fine powder is molded to obtain a molding; and a sintering step in which the molding is sintered at 1,250-1,450°C in an oxygenous atmosphere or sintered at 1,100-1,250°C in an oxygenous atmosphere with pressurizing to thereby obtain a sinter.

Description

Production method of IPO sputtering target {PROCESS FOR PRODUCING IZO SPUTTERING TARGET}

The present invention relates to a method for producing an IZO sputtering target mainly composed of indium oxide and zinc oxide or these powders.

Recently, display devices have been developed remarkably, and liquid crystal displays, electroluminescent displays, field emission displays, and the like have been developed for office equipment such as personal computers, word processors, and control systems in factories. And all of these display apparatuses have the sandwich structure which sandwiched the display element by the transparent conductive film.

As the transparent conductive film used for these display devices, an indium tin oxide (hereinafter, abbreviated as ITO) film occupies the mainstream. This is because the ITO film is not only excellent in transparency and conductivity, but also can be etched by a strong acid, and also excellent in adhesion to the substrate. In general, this ITO film is formed by a sputtering method, an ion plating method, or a vapor deposition method.

However, ITO has excellent performance with respect to the above properties, but since it is a crystalline metal oxide, when the film is formed by sputtering or the like using a target of ITO, crystallization of ITO proceeds, and when the crystal grows, transparent conductivity is achieved. There is a problem that crystal grains are formed on the surface of the film and the surface precision of the film is lowered.

In addition, since this ITO has crystallinity, it is etched from the interface part of the crystal grain of a transparent conductive film at the time of an etching process. In this case, this crystal grain is left in the etching site | part of a transparent conductive film, and when it is set as a display element, there also exists a problem that it becomes a cause of the display defect by conduction.

Thus, for example, zinc oxide and tin oxide as a main raw material, antimony added to tin oxide, aluminum added to zinc oxide, or indium oxide and zinc oxide as a main component by combinations other than ITO. IZO etc. which are mentioned are proposed (for example, refer patent document 1, patent document 2). Among them, IZO, which has indium oxide and zinc oxide as its main components, has attracted attention in that it has a feature that the etching rate is higher than that of ITO.

In general, ITO sputtering targets are manufactured through a number of processes such as mixing, pulverizing, drying, calcining, pulverizing, granulating, shaping, and sintering an indium oxide and zinc oxide powder (for example, See Patent Document 3). The production of sputtering targets having undergone such a large number of processes causes a decrease in productivity and an increase in cost, but improvements such as reduction of processes have not been sufficiently studied. Also in the manufacture of an IZO sputtering target, the conventional manufacturing process is followed, and the improvement in the manufacturing aspect, such as reduction of a process, is not performed, and the improvement of productivity and reduction of a manufacturing cost are calculated | required.

Patent Document 1: Japanese Unexamined Patent Publication No. 1996-171824

Patent Document 2: Japanese Unexamined Patent Publication No. 2000-256059

Patent Document 3: International Publication No. WO2003 / 14409

Disclosure of the Invention

Problems to be Solved by the Invention

Under such circumstances, an object of the present invention is to provide a manufacturing method in which the production of the IZO sputtering target can be improved and productivity can be reduced by reducing the process while maintaining the characteristics of the IZO sputtering target. Moreover, it aims at providing the manufacturing method which can make productivity improvement and the manufacturing cost reduce by making sintering temperature low.

Means to solve the problem

The present inventors have intensively researched to achieve the above object, and as a result, by using indium oxide powder and zinc oxide powder having specific properties or raw material powder containing these powders as main components, the characteristics as IZO sputtering targets are maintained. It has been found that the manufacturing process can be reduced. The present invention has been completed based on these findings.

That is, the present invention,

(1) A mixed grinding step of mixing and grinding an indium oxide powder and a zinc oxide powder or a raw material powder containing these powders as a main component to obtain a fine powder, a molding step of molding the fine powder to obtain a molded article, and the molded article A process for producing an IZO sputtering target, comprising a sintering step of sintering at 1250 to 1450 ° C. in an oxygen atmosphere or at 1100 to 1250 ° C. in an oxygen atmosphere under pressure. A method for producing an IZO sputtering target, wherein the specific surface area of the powder is 8 to 10 m 2 / g, and the specific surface area of the zinc oxide powder is 10 m 2 / g or more,

(2) a mixed grinding step of mixing and grinding an indium oxide powder and a zinc oxide powder or a raw material powder containing the powder as a main component thereof, a molding step of molding the fine powder to obtain a molded product, and the molded product in an oxygen atmosphere. A method for producing an IZO sputtering target, comprising a sintering step of obtaining a sintered body at 1250 to 1450 ° C. or by pressurizing the molding at 1100 to 1250 ° C. in an oxygen atmosphere. Preparation of IZO sputtering target whose median diameter is 1-2 micrometers, the median diameter of the particle size distribution of the said zinc oxide powder is 65 nm-0.2 micrometer, and the average median diameter after the said mixed grinding process is 0.5-1 micrometer. Way,

(3) The method for producing the IZO sputtering target according to the above (1) or (2), which is not calcined before the forming step, and

(4) The method for producing an IZO sputtering target according to any one of (1) to (3), wherein the density of the sintered compact is 6.5 g / cm 3 or more.

To provide.

Effects of the Invention

Industrial Applicability According to the present invention, in the production of an IZO sputtering target, it is possible to provide a manufacturing method which enables improvement of productivity and reduction of manufacturing cost by reducing the process while maintaining the characteristics of the IZO sputtering target. In addition, by lowering the sintering temperature, it is possible to provide a manufacturing method which enables improvement of productivity and reduction of manufacturing cost.

Implement the invention  Best form for

[Raw powder]

This invention makes it possible to reduce a manufacturing process by using indium oxide powder and zinc oxide powder which have a specific characteristic, or the raw material powder which has these powder as a main component.

The specific surface areas of the indium oxide powder and the zinc oxide powder used as raw materials in the present invention are 8 to 10 m 2 / g and 10 m 2 / in order to reduce the occurrence of defects called white spots (white spot stains) on the surface of the sputtering target, respectively. It is required to be at least g.

In addition, the median diameter of the particle size distribution of the indium oxide powder and the zinc oxide powder used as a raw material in the present invention is required to be 1 to 2 µm and 65 nm to 0.2 µm, respectively, in order to reduce the expression of the white spot. The finer the average median diameter of the fine powder after the mixed grinding step, the finer it is, but it is pulverized so as to be 0.5 to 1 m. If it exists in this range, a high density IZO sputtering target can be obtained and the amount of mixing of impurities from the grinder etc. at the time of grinding | pulverization can be reduced. On the other hand, it is preferable that the powder used as the raw material satisfies both the specific surface area and the median diameter.

As for the usage-amount of the said indium oxide powder and zinc oxide powder, 75: 25-95: 5 are preferable by weight ratio, and 80: 20-94: 6 are more preferable.

As long as the raw material of the IZO sputtering target which concerns on manufacture of this invention has indium oxide and zinc oxide as a main component, you may add another component for the purpose of improving the characteristic of the said target. For example, in order to lower the bulk electrical resistance of an IZO sputtering target, + tetravalent elements, such as about 100-2000 ppm of tin, zirconium, titanium, hafnium, germanium, and cerium, can be added.

[Manufacturing method]

An IZO sputtering target is manufactured as follows. The fine powder obtained by wet-pulverizing wet powder of an indium oxide powder and a zinc oxide powder or a mixture containing these powders as a main component is pressed and sintered to dry the particles dried using a spray dryer or the like, followed by cutting to the sintered compact of the molded product. It can manufacture by doing.

The mixed grinding step is uniformly mixing and grinding the indium oxide powder and zinc oxide powder or a raw material powder containing these powders as a main component by using a wet mixing mill, for example, a wet ball mill, bead mill, or ultrasonic wave. To obtain fine powder. The particle size of the pulverized fine powder is adjusted in view of the density of the IZO sputtering target and the amount of mixing of impurities from the pulverizer and the like during pulverization as described above.

Next, the obtained fine powder is dried. A spray dryer, a general powder dryer, etc. can be used for drying fine powder.

The dry fine powder is subjected to a molding step of filling into a mold and press molding into a desired shape using a common cold press machine or the like. Press molding can be performed using a uniaxial press, cold hydrostatic press (CIP), or the like.

The molded article obtained by press molding becomes a sintered compact for IZO sputtering targets through a sintering process. Sintering is performed in oxygen atmosphere. An oxygen atmosphere means that oxygen concentration is 21%-less than 50%, Preferably it is 21%-less than 40%. If it exists in this range, it can be sintered efficiently and a firing furnace will not burn out. On the other hand, it can sinter in air atmosphere. In addition, sintering may be performed at atmospheric pressure, and may be performed at atmospheric pressure above 0.5 MPa under pressure in order to make the sintering density high, and to prevent the cost of the sintering apparatus containing a sintering furnace from increasing.

In the case of sintering under atmospheric pressure, the sintering temperature is 1250 to 1400 ° C, preferably 1300 to 1400 ° C. If it is within this range, the sintering density is high and the production cost can be reduced. The sintering time is in the range of 2 to 48 hours, preferably 4 to 36 hours, in order to increase the sinter density and reduce the production cost, and the preferable temperature increase rate at the time of sintering is 2 to 24 ° C / min.

In the case of sintering under pressure, the sintering temperature is 1100 to 1250 ° C, preferably 1150 to 1250 ° C, and it is possible to sinter at a lower temperature than when sintering under atmospheric pressure. It can increase and manufacturing cost can be reduced. The sintering time is in the range of 2 to 48 hours, preferably 10 to 36 hours, in order to increase the sinter density and reduce the production cost, and the preferable temperature increase rate during sintering is 2 to 24 ° C / min.

In order to produce a sputtering target from the sintered compact of the obtained molded object, this sintered compact can be cut into the shape suitable for attachment to a sputtering apparatus, and a mounting jig can also be provided in this. At this time, in order to improve the average surface roughness of the said target, you may perform mirror surface processing. In this mirror working, a general polishing method such as chemical polishing, mechanical polishing, chemical mechanical polishing, or the like can be used.

Thus, by using the indium oxide powder and zinc oxide powder which have a specific characteristic, or the raw material powder which has these powder as a main component, generally it does not go through the calcination process performed before the shaping | molding process by press molding, and it is 6.9g / under atmospheric pressure. A sintered compact for IZO sputtering targets having a high density of cm 3 or more can be obtained. Furthermore, under pressure, a sintered compact for IZO sputtering targets having a high density of 6.5 g / cm 3 or more can be obtained. The IZO sputtering target manufactured by cutting the obtained sintered compact is high density, and has the outstanding characteristic that the defect called a white spot (white spot unevenness) does not exist in the said target surface. The manufacturing method of this invention aims at the improvement of productivity and reduction of a manufacturing cost by reducing a process, maintaining the characteristic of an IZO sputtering target.

The IZO sputtering target obtained by the manufacturing method of this invention suppresses generation | occurrence | production of black precipitate (projection) called a nodule on a target surface, when forming into a film by sputtering method by having the above characteristics. Therefore, since the film forming speed is not lowered and foreign matters are not mixed into the transparent conductive film by the nodules scattered by abnormal discharge, it is possible to provide a stable conductive sputtering and to provide a transparent conductive film with excellent film characteristics. You can get it.

Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited at all by these Examples.

Example 1

90 parts by weight of indium oxide powder having a specific surface area of 9 m 2 / g and 10 parts by weight of zinc oxide powder having a specific surface area of 12 m 2 / g were mixed and ground for 24 hours using a wet bead mill. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged to a calcination furnace and sintered at 1350 ° C. for 4 hours in an oxygen atmosphere having an oxygen concentration of 25%. The obtained IZO sputtering target sintered compact was a high density sintered compact at 6.92 g / cm <3>, although there was no calcination process.

Example 2

90 parts by weight of the indium oxide powder having a median diameter of 1.5 µm and 10 parts by weight of the zinc oxide powder having a median diameter of 0.1 µm were mixed and ground for 24 hours using a wet bead mill, and the median diameter after grinding was 0.8 µm. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged to a kiln and sintered at 1280 ° C for 4 hours in an oxygen atmosphere having an oxygen concentration of 30%. The obtained IZO sputtering target sintered compact was a high density sintered compact at 6.91 g / cm <3>, although there was no calcination process.

Example 3

90 parts by weight of indium oxide powder having a specific surface area of 9 m 2 / g and 10 parts by weight of zinc oxide powder having a specific surface area of 12 m 2 / g were mixed and ground for 24 hours using a wet bead mill. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged to a calcination furnace, and placed under pressure of 0.15 MPa and sintered at 1230 ° C. for 24 hours in an oxygen atmosphere having an oxygen concentration of 25%. The obtained IZO sputtering target sintered compact was a high density sintered compact at 6.72 g / cm <3>, although there was no calcination process.

Example 4

90 parts by weight of the indium oxide powder having a median diameter of 1.5 µm and 10 parts by weight of the zinc oxide powder having a median diameter of 0.1 µm were mixed and ground for 24 hours using a wet bead mill, and the median diameter after grinding was 0.8 µm. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged to a sintering furnace and placed under pressure of 0.12 MPa and sintered at 1180 ° C. for 24 hours in an oxygen atmosphere having an oxygen concentration of 30%. The obtained sinter for IZO sputtering target was a high density sintered compact at 6.65 g / cm <3>, although there was no calcination process.

Comparative Example 1

90 parts by weight of indium oxide powder having a specific surface area of 9 m 2 / g and 10 parts by weight of zinc oxide powder having a specific surface area of 3 m 2 / g were mixed and ground for 24 hours using a wet bead mill. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged into a calcination furnace and sintered at 1400 ° C. for 4 hours in an oxygen atmosphere having an oxygen concentration of 25%. The density of the sintered compact for IZO sputtering targets obtained was as low as 6.10 g / cm <3>.

Comparative Example 2

90 parts by weight of the indium oxide powder having a median diameter of 1.5 µm and 10 parts by weight of the zinc oxide powder having a median diameter of 1.0 µm were mixed and ground for 24 hours using a wet bead mill, and the median diameter after grinding was 1.2 µm. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged into a calcination furnace and sintered at 1400 ° C. for 10 hours in an oxygen atmosphere having an oxygen concentration of 25%. The density of the obtained IZO sputtering target sintered compact was as low as 6.00 g / cm <3>.

Comparative Example 3

Comparative Examples 1 and 2, except that after calcining and before press molding, calcining was carried out at 1200 ° C. for 2 hours in an air atmosphere, and the resulting calcined powder was ground using a wet bead mill. A sintered compact for IZO sputtering targets was obtained in the same manner as in 1 and Comparative Example 2. The density of the obtained sintered compact was increased to 6.73 g / cm <3> and 6.73 g / cm <3>, respectively, compared with the comparative examples 1 and 2. As shown in FIG. The increase in density was caused by calcination, but still not the density of Examples 1 and 2, and the productivity was lowered by the addition of the calcination step and the grinding step.

Comparative Example 4

90 parts by weight of indium oxide powder having a specific surface area of 9 m 2 / g and 10 parts by weight of zinc oxide powder having a specific surface area of 3 m 2 / g were mixed and ground for 24 hours using a wet bead mill. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged to a baking furnace and sintered at 1400 degreeC and atmospheric pressure for 24 hours in air atmosphere. The density of the sintered compact for IZO sputtering targets obtained was as low as 6.10 g / cm <3>.

Comparative Example 5

90 parts by weight of the indium oxide powder having a median diameter of 1.5 µm and 10 parts by weight of the zinc oxide powder having a median diameter of 1.0 µm were mixed and ground for 24 hours using a wet bead mill, and the median diameter after grinding was 1.2 µm. Zirconia beads of 1 mmφ were used as the medium. After mixing and pulverizing, the fine powder obtained by drying with a spray dryer was filled into a mold and press-molded at 1 t / cm 2 using a cold press and a cold isostatic press. The obtained molded product was charged to a baking furnace and sintered at 1200 degreeC and atmospheric pressure for 24 hours in air atmosphere. The density of the obtained IZO sputtering target sintered compact was as low as 6.00 g / cm <3>.

Comparative Example 6

Comparative Examples 4 and 5, except that after calcining and before press molding, calcining was performed at 1200 ° C. for 2 hours in an air atmosphere, and the resulting calcined powder was ground using a wet bead mill. A sintered compact for IZO sputtering targets was obtained in the same manner as in 1 and Comparative Example 2. The density of the obtained sintered compact was increased to 6.73 g / cm <3> and 6.73 g / cm <3>, respectively, compared with the comparative examples 4 and 5. As shown in FIG. The increase in density was caused by sintering, whereby a sintered body having a higher density than those in Examples 3 and 4 was obtained, but the productivity was lowered by the addition of the sintering step and the grinding step.

Production of the IZO sputtering target of this invention can improve productivity and reduce manufacturing cost by reducing a process, maintaining the characteristic as an IZO sputtering target. In addition, by lowering the sintering temperature, productivity can be improved and manufacturing costs can be reduced.

Claims (4)

A mixed grinding step of mixing and grinding an indium oxide powder and a zinc oxide powder or a raw material powder containing these powders as a main component to obtain fine powder, a molding step of molding the fine powder to obtain a molded product, and the molded product in an oxygen atmosphere of 1250 to 1450. A method for producing an IZO sputtering target, comprising a sintering step of obtaining a sintered body by sintering at 1 ° C. or at 1100 to 1250 ° C. in an oxygen atmosphere under pressurization of the molded product. The manufacturing method of the IZO sputtering target which is 10 m <2> / g and the specific surface area of the said zinc oxide powder is 10 m <2> / g or more. A mixed grinding step of mixing and grinding an indium oxide powder and a zinc oxide powder or a raw material powder containing these powders as a main component to obtain a fine powder, a molding step of molding the fine powder to obtain a molded product, and the molded product in an oxygen atmosphere at 1250 to 1450 ° C. Or a sintering step of obtaining a sintered body by sintering at 1100 to 1250 ° C. in an oxygen atmosphere under pressurization of the molding, wherein the median diameter of the particle size distribution of the indium oxide powder is A method for producing an IZO sputtering target having a thickness of 1 to 2 µm, a median diameter of the particle size distribution of the zinc oxide powder is 65 nm to 0.2 µm, and an average median diameter after the mixed grinding step. The method according to claim 1 or 2, A method for producing an IZO sputtering target, characterized in that it is not calcined before the forming step. The method according to any one of claims 1 to 3, The density of the said sintered compact is 6.5 g / cm <3> or more, The manufacturing method of the IZO sputtering target characterized by the above-mentioned.