JP2020117415A - MANUFACTURING METHOD OF Sn-Zn-O-BASED OXIDE SINTERED BODY, Sn-Zn-O-BASED OXIDE SINTERED BODY, AND Sn-Zn-O-BASED OXIDE TARGET - Google Patents

Abstract

To provide a manufacturing method of a Sn-Zn-O-based oxide sintered body capable of suppressing occurrence of arcing during deposition by a sputtering method, among the Sn-Zn-O-based oxide sintered bodies containing Zn and Sn as a main component.SOLUTION: The manufacturing method of a Sn-Zn-O-based oxide sintered body containing Zn and Sn as a main component includes a granulation step S1 for producing a granulated powder by mixing a zinc oxide powder, a tin oxide powder, an oxide powder containing a first additive element M, and a tantalum oxide powder, a forming step S2 for pressure forming the granulated powder to make a formed body, and a firing step S3 for making an oxide sintered body by firing the formed body, in which the first additive element M is at least one selected from Si, Ti, Ge, In, Bi, Ce, Al and Ga, and the tantalum oxide powder has a D90 of 5 μm or less.SELECTED DRAWING: Figure 1

Description

The present invention is a Sn—Zn—O-based oxide sintered material used as a sputtering target when a transparent conductive film applied to a solar cell, a liquid crystal display device, a touch panel, etc. is manufactured by a sputtering method such as DC sputtering or high frequency sputtering. The present invention relates to a method for manufacturing a body, a Sn-Zn-O-based oxide sintered body, and a Sn-Zn-O-based oxide target.

The transparent conductive film having high conductivity and high transmittance in the visible light region is used for solar cells, liquid crystal display elements, surface elements such as organic electroluminescence and inorganic electroluminescence, and touch panel electrodes, etc. It is also used as a transparent heating element for various anti-fog applications such as heat ray reflective films for automobile windows and buildings, antistatic films, and freezer showcases.

Examples of the transparent conductive film include tin oxide (SnO ₂ ) containing antimony and fluorine as dopants, zinc oxide (ZnO) containing aluminum and gallium as dopants, and indium oxide (In ₂ O ₃ ) containing tin as a dopant. Are known. In particular, indium oxide _(In 2 _{O 3)} film containing tin as a dopant, i.e., an In-Sn-O based film is referred to as ITO (Indium tin oxide) film, since the low-resistance film can be easily obtained Widely used.

As a method of manufacturing the transparent conductive film, a sputtering method such as direct current sputtering or high frequency sputtering is often used. The sputtering method is an effective method when film formation of a material having a low vapor pressure or precise film thickness control is required, and the operation is extremely simple, and is widely used industrially.

To manufacture the transparent conductive film, indium oxide-based materials such as ITO have been widely used. However, since indium metal is a rare metal, and toxic indium metal is feared to adversely affect the environment and the human body, a non-indium-based material is required.

As the non-indium-based material, as described above, a zinc oxide (ZnO)-based material containing aluminum or gallium as a dopant and a tin oxide (SnO ₂ )-based material containing antimony or fluorine as a dopant are known. .. The zinc oxide (ZnO)-based transparent conductive film is industrially manufactured by a sputtering method, but it has drawbacks such as poor chemical resistance (alkali resistance and acid resistance). On the other hand, although the transparent conductive film of a tin oxide (SnO ₂ )-based material has excellent chemical resistance, it is difficult to manufacture a tin oxide-based sintered compact target having high density and durability, and thus the transparent conductive film is sputtered. It had a drawback that it was difficult to manufacture by the method.

Therefore, as a material for improving these drawbacks, a sintered body containing zinc oxide and tin oxide as main components has been proposed. For example, Patent Document 1 presents a Sn—Zn—O-based oxide sintered body containing zinc oxide and tin oxide as main components and containing two kinds of additive elements in a predetermined ratio, and a method for producing the same. ..

JP, 2017-145185, A

However, depending on the manufacturing conditions of the Sn—Zn—O-based oxide sintered body, abnormal sputtering (arcing) occurs during film formation when the sputtering method is performed using a target made of the sintered body, and the transparent conductive film In some cases, stable film formation may be difficult.

The present invention has been made paying attention to such circumstances, and suppresses arcing during film formation by a sputtering method in a Sn—Zn—O-based oxide sintered body containing Zn and Sn as main components. It is an object of the present invention to provide a method for producing an Sn-Zn-O-based oxide sintered body that can be manufactured.

One embodiment of the present invention is a method for manufacturing a Sn—Zn—O-based oxide sintered body containing zinc (Zn) and tin (Sn) as main components, in which zinc oxide powder, tin oxide powder, and 1 a granulating step of mixing an oxide powder containing an additional element M and a tantalum oxide powder to produce a granulated powder, and a molding step of press-molding the granulated powder to obtain a molded body, And a firing step for obtaining an oxide sintered body by firing the molded body, wherein the first additional element M is at least 1 selected from Si, Ti, Ge, In, Bi, Ce, Al and Ga. The tantalum oxide powder has a D90 of 5 μm or less.

This makes it possible to suppress the occurrence of arcing during film formation by the sputtering method in the target made of the obtained Sn—Zn—O-based oxide sintered body.

At this time, in one aspect of the present invention, the firing step may be performed at a temperature of 1200°C or more and 1450°C or less for 10 hours or more and 30 hours or less in an atmosphere having an oxygen concentration of 70% by volume or more.

By doing so, the Sn—Zn—O-based oxide sintered body sintered body becomes more dense.

At this time, in one aspect of the present invention, the tantalum oxide powder may be a powder obtained by performing wet pulverization.

By doing so, it is possible to more reliably suppress the occurrence of arcing during film formation in the sputtering method.

One embodiment of the present invention is a Sn—Zn—O-based oxide sintered body containing zinc (Zn) and tin (Sn) as main components, further containing a first additive element M and tantalum (Ta), The tin is contained in an atomic number ratio Sn/(Sn+Zn) of 0.1 or more and 0.9 or less, and the first additive element M is Si, Ti, Ge, In, Bi, Ce, Al or Ga. Is at least one selected from the above, and the first additive element M is contained at a ratio of 0.0001 or more and 0.04 or less as an atomic ratio M/(Sn+Zn+M+Ta) with respect to the total amount of all metal elements, and Ta is , The atomic ratio Ta/(Sn+Zn+M+Ta) with respect to the total amount of all metal elements in a ratio of 0.005 or more and 0.1 or less, and 3 black dots/m ² having a diameter of 2 mm or more on the surface of the oxide sintered body. It is characterized by the following.

By doing so, it is possible to suppress the occurrence of arcing during film formation by the sputtering method in the target formed of the Sn—Zn—O-based oxide sintered body.

At this time, in one embodiment of the present invention, the relative density of the Sn—Zn—O-based oxide sintered body may be 90% or more and the specific resistance may be 1 Ω·cm or less.

The dense and durable oxide sintered body is useful as a sputtering target.

At this time, in one embodiment of the present invention, a Sn—Zn—O-based oxide target may be formed by joining a backing plate to the Sn—Zn—O-based oxide sintered body.

By doing so, it is possible to suppress the occurrence of arcing during film formation in the sputtering method.

With the method for producing a Sn—Zn—O-based oxide sintered body according to the present invention, it is possible to obtain a Sn—Zn—O-based oxide sintered body with less arcing during film formation in the sputtering method.

FIG. 1 is a process diagram showing an outline of a process in a method for manufacturing a Sn—Zn—O-based oxide sintered body according to an embodiment of the present invention. FIG. 2 is a photograph showing a state of the surface of the Sn—Zn—O-based oxide sintered body according to the embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unreasonably limit the content of the present invention described in the claims, and can be modified without departing from the gist of the present invention. In addition, not all the configurations described in the present embodiment are essential as the solving means of the present invention.

The present inventors have earnestly studied to solve the above-mentioned problems. He discovered that black spots appeared on the surface of the target that showed arcing. Small particles believed to be ZnTa ₂ O ₆ were scattered in the black dots, and the black dots had high resistance. Further, coarse black spots, for example, black spots having a diameter of 2 mm or more may appear, and the detailed reason is unknown, but a correlation was found between the number of coarse black spots and the degree of arcing. From this, coarse black dots were speculated to be the cause of arcing.

Then, the present inventors have found that among the zinc oxide powder, the tin oxide powder, the oxide powder containing the first additional element M, and the tantalum oxide powder, which are the raw materials of the target, It was found that the particle size distribution of the raw material lot is related to the number of coarse black spots on the target. Specifically, it has been found that the larger the average particle size of the Ta ₂ O ₅ powder used for the addition of Ta, the larger the number of generation of coarse black spots and the more frequent occurrence of arcing. Then, the present inventors have completed the present invention from such knowledge. The details will be described below.
1. Method for producing Sn-Zn-O-based oxide sintered body 1-1. Granulation process 1-2. Molding process 1-3. Firing process 2. Sn—Zn—O-based oxide sintered body 3. Sn-Zn-O-based oxide target

<1. Method for producing Sn-Zn-O-based oxide sintered body>
A method for manufacturing the Sn—Zn—O-based oxide sintered body of the present invention will be described. FIG. 1 is a process diagram showing an outline of a process in a method for manufacturing a Sn—Zn—O-based oxide sintered body according to an embodiment of the present invention. One embodiment of the present invention is a method of manufacturing a Sn—Zn—O-based oxide sintered body containing zinc (Zn) and tin (Sn) as main components, in which zinc oxide powder, tin oxide powder, Granulation step S1 for producing a granulation powder by mixing the oxide powder containing the first additional element M and the tantalum oxide powder, and the molding step S2 for press-molding the granulation powder to obtain a compact. And a firing step S3 for firing the molded body to obtain an oxide sintered body.

Then, in the granulating step S1, the first additive element M and the second additive element, tantalum, are mixed so as to have a predetermined ratio, whereby a high density and low resistance Sn—Zn—O-based oxide sintered body is obtained. Can be manufactured.

Further, by controlling the powder of tantalum oxide to have a predetermined particle size before mixing, it is possible to more reliably prevent the generation of coarse black spots and the occurrence of arcing.

In addition, the Sn-Zn-O-based oxide sintered body according to the present invention, in which the number of coarse black spots having a diameter of 2 mm or more is 3 pieces/m ² or less on the target surface by setting the firing process to a predetermined condition described below. Can be manufactured. Hereinafter, each step will be described individually.

(1-1. Granulating step S1)
First, in the granulation step S1, the main raw material is prepared. The tin oxide and zinc oxide, which are the main raw materials, are tin zinc oxide compounds alone or a mixed powder of tin oxide and zinc oxide. Further, it is preferable that Sn is contained at a ratio of 0.1 or more and 0.9 or less as the atomic ratio Sn/(Sn+Zn). It is preferable to use a mixed powder of tin oxide and zinc oxide as the main raw material because the blending ratio can be easily adjusted. For example, this raw material powder is SnO ₂ powder and ZnO powder. In addition, an oxide powder containing a first additive element M and an oxide powder containing a second additive element tantalum, which will be described later, are prepared and added to the main raw material to be mixed. For example, GeO ₂ powder as the first additive element M and Ta ₂ O ₅ powder as the second additive element are prepared and added to the main raw material to be mixed.

In the granulation step S1, the metal atom number ratio is such that Sn/(Sn+Zn) is 0.1 or more and 0.9 or less, M/(Sn+Zn+M+Ta) is 0.0001 or more and 0.04 or less, and Ta/(Sn+Zn+M+Ta) is 0. It is preferable to mix the powder of zinc oxide, the powder of tin oxide, and the powder of oxide containing an additional element so as to be 005 or more and 0.1 or less. In this way, by mixing Sn/(Sn+Zn) at a ratio of 0.1 or more and 0.9 or less, and as described above, the first additive element M and tantalum (Ta) are mixed at a predetermined ratio. A high density and low resistance Sn—Zn—O based oxide sintered body can be manufactured. As a result of an experiment by a conventional method, when Ta/(Sn+Zn+M+Ta) was 0.005 or more, arcing was remarkable, and when it was less than 0.005, black spots were not generated and arcing was not generated.

In the granulating step S1, the zinc oxide powder and the tin oxide powder preferably have an average particle size (corresponding to D50) of 10 μm or less. The oxide powder containing the first additional element M and the Ta ₂ O ₅ powder containing the second additional element tantalum preferably have an average particle size of 20 μm or less. By preparing a powder having an average particle diameter within the above range, a high density and low resistance Sn—Zn—O based oxide sintered body can be obtained.

(Pulverization of Ta ₂ O ₅ powder)
Here, in the Ta ₂ O ₅ powder containing the second additive element tantalum, D90 is 5 μm or less. As described above, small particles that are considered to be ZnTa ₂ O ₆ are scattered in the black dots. By reducing the particle size of the Ta ₂ O ₅ powder and controlling the particle size distribution of the Ta ₂ O ₅ powder so that the Ta ₂ O ₅ powder having a large particle size within the particle size distribution is reduced, Sn-Zn- It is possible to make the element distribution in the O-based oxide sintered body uniform and prevent the precipitation of small particles such as ZnTa ₂ O ₆ . Then, it is possible to prevent the occurrence of coarse black spots and the occurrence of arcing. When D90 exceeds 5 μm, it becomes difficult to prevent the generation of coarse black spots and arcing. The lower limit of D90 is not particularly specified, but is preferably 1 μm or more from the viewpoint of productivity and contamination from the beads used. The particle size distribution of the Ta ₂ O ₅ powder is controlled by milling the _Ta 2 _{O 5} powder. The pulverization method of the Ta ₂ O ₅ powder is not particularly limited as long as the particle size distribution can be controlled, but it is preferable to perform wet pulverization with a bead mill. For example _Ta 2 _{O 5} powder together with such pure water or a dispersant to prepare a slurry, subjected to wet grinding in a bead mill device, so as to achieve the range of _Ta 2 _{O 5} powder D90, _Ta 2 _{O 5} during powder pulverization The number of rotations, the number of passes, the diameter and material of the beads used for pulverization, and the Ta ₂ O ₅ slurry concentration are adjusted appropriately.

Further, it is preferable that the Ta ₂ O ₅ powder is pulverized before being added to the main raw material such as tin oxide or zinc oxide. As will be described later, wet pulverization is performed even after the addition to the main raw material, and the average particle diameter (D50) of the granulated powder is set to 1 μm or less. However, although Ta is effective even when added in a small amount, Ta ₂ O ₅ powder may not be sufficiently pulverized when the addition amount is small. By pulverizing the Ta ₂ O ₅ powder in advance and controlling it to have a predetermined particle size distribution, it is possible to more reliably prevent the generation of black spots and the occurrence of arcing. Note that D90 means a particle size in which the volume of each particle is accumulated from the side having a smaller particle size, and the cumulative volume is 90% of the total volume of all particles.

(Granulation of raw material powder)
Raw material powders other than tantalum prepared by the above method are combined with pure water, a binder, a dispersant, etc. to form a slurry. A slurry of wet-milled tantalum is mixed with this slurry. Then, using a bead mill in which hard ZrO ₂ balls are charged, wet milling is performed until the average particle diameter (D50) of the raw material powder becomes 1 μm or less, and then mixed and stirred for 10 hours or more to obtain a slurry. A granulated powder can be obtained by spraying and drying the obtained slurry with a spray dryer device or the like.

(1-2. Molding step S2)
The molding step S2 is a step of pressure-molding the granulated powder obtained in the granulation step S1 to obtain a molded body. In the molding step S2, pressure molding is performed at a pressure of, for example, about 294 MPa (3.0 ton/cm ² ) in order to remove pores between the particles of the granulated powder. The method of pressure molding is not particularly limited, but, for example, a cold isostatic press (CIP: Cold Isostatic) capable of filling a rubber mold with the granulated powder obtained in the granulation step S1 and applying high pressure thereto. Press) is preferably used.

(1-3. Firing step S3)
The firing step S3 is a step of obtaining the sintered body by firing the formed body obtained in the forming step S2 in a sintering furnace at a predetermined temperature rising rate, a predetermined temperature and a predetermined time.

(Atmosphere in furnace)
It is preferable to fire the molded body in an atmosphere in which the oxygen concentration is 70% by volume or more in the sintering furnace. This is because it has the effect of promoting diffusion of ZnO, SnO ₂ and Zn ₂ SnO ₄ compounds, improving sinterability and improving conductivity. In the high temperature region, it also has an effect of suppressing volatilization of ZnO and Zn ₂ SnO ₄ .

On the other hand, if the oxygen concentration in the sintering furnace is less than 70% by volume, the diffusion of ZnO, SnO ₂ and Zn ₂ SnO ₄ compounds declines, which is not preferable. Further, in the high temperature range, volatilization of the Zn component is promoted and it is difficult to produce a dense sintered body, which is not preferable.

(Sintering temperature)
The sintering temperature is preferably 1200°C or higher and 1450°C or lower. When the sintering temperature is less than 1200° C., the temperature is too low and the grain boundary diffusion of sintering in the ZnO, SnO ₂ , Zn ₂ SnO ₄ compound does not proceed. On the other hand, when the temperature exceeds 1450° C., grain boundary diffusion is promoted and sintering proceeds, but even if firing is performed in a furnace with an oxygen concentration of 70 vol% or more, volatilization of the Zn component can be suppressed. Instead, large holes are left inside the sintered body.

(Holding time)
The holding time is preferably 10 hours or more and 30 hours or less. If it is less than 10 hours, the sintering will be incomplete, resulting in a sintered body with large strain and warpage, and at the same time, the grain boundary diffusion will not proceed and the sintering will not proceed. As a result, a dense sintered body cannot be manufactured. On the other hand, when it exceeds 30 hours, the effect of time is not particularly obtained, resulting in deterioration of work efficiency and high cost.

<2. Sn-Zn-O-based oxide sintered body>
The Sn-Zn-O-based oxide sintered body of the present invention will be described. A Sn-Zn-O-based oxide sintered body according to an embodiment of the present invention is a Sn-Zn-O-based oxide sintered body containing zinc (Zn) and tin (Sn) as main components. It contains the first additive element M and tantalum (Ta), and contains tin in a ratio of 0.1 or more and 0.9 or less as the atomic ratio Sn/(Sn+Zn), and the first additive element M is Si or Ti. , Ge, In, Bi, Ce, Al and Ga, and the first additive element M is 0.0001 or more as an atomic ratio M/(Sn+Zn+M+Ta) with respect to the total amount of all metal elements. It is contained at a ratio of 04 or less, and Ta is contained at a ratio of 0.005 or more and 0.1 or less as an atomic ratio Ta/(Sn+Zn+M+Ta) with respect to the total amount of all metal elements. The number of black spots having a diameter of 2 mm or more on the surface of the oxide sintered body is 3 pieces/m ² or less.

(Additional element)
The Sn—Zn—O-based oxide sintered body according to the embodiment of the present invention is provided with a Sn-Zn-O-based oxide sintered body under the condition that Sn is contained in an atomic ratio Sn/(Sn+Zn) of 0.1 or more and 0.9 or less. The inclusion of the 1st additional element M and the 2nd additional element Ta is required. On the other hand, when only the first additive element M is contained, the density is improved but a low resistance sintered body cannot be obtained. On the other hand, when the second additive element Ta alone is contained, a high density sintered body cannot be obtained although the resistance becomes low.

That is, by containing the first additive element M and the second additive element Ta in the above atomic number ratio range, it becomes possible to obtain a Sn—Zn—O-based oxide sintered body of high density and low resistance. ..

(First additional element M)
For the densification of the oxide sintered body, the effect of increasing the density by adding at least one first additive element M selected from Si, Ti, Ge, In, Bi, Ce, Al and Ga Can be obtained. It is considered that the first additional element M promotes grain boundary diffusion, assists neck growth between grains, strengthens the bond between grains, and contributes to densification. Here, the atomic number ratio M/(Sn+Zn+M+Ta) of the first additive element M to the total amount of all metal elements is set to 0.0001 or more and 0.04 or less because the atomic number ratio M/(Sn+Zn+M+Ta) is 0.0001. If it is less than the range, the effect of increasing the density cannot be obtained. On the other hand, when the atomic ratio M/(Sn+Zn+M+Ta) exceeds 0.04, the conductivity of the oxide sintered body does not increase even if the second additive element Ta described later is added. Furthermore, another compound such as SiO ₂ , TiO ₂ , Al ₂ O ₃ , ZnAl ₂ O ₄ , ZnSiO ₄ , Zn ₂ Ge ₃ O ₈ , ZnTa ₂ O ₆ , Ti _0.5 Sn _0.5 O ₂ or the like. The desired film characteristics cannot be obtained when a film is formed, such as when the compound of (3) is produced.

Thus, only by adding the first additive element M, the density of the oxide sintered body is improved, but the conductivity is not improved.

(Second additional element Ta)
The Sn-Zn-O-based oxide sintered body to which the first additional element M is added under the condition that Sn is contained at a ratio of 0.1/0.9 or less as the atomic ratio Sn/(Sn+Zn) is as described above. As described above, the density is improved, but there is a problem in conductivity.

Therefore, the second additive element Ta is added. The addition of the second additive element Ta improves the conductivity while maintaining the high density of the oxide sintered body.

As for the amount to be added, the atomic ratio Ta/(Sn+Zn+M+Ta) of the second additive element Ta to the total amount of all metal elements is required to be 0.005 or more and 0.1 or less. By setting the atomic ratio Ta/(Sn+Zn+M+Ta) within the above range, it is possible to suppress the generation of black spots and enhance the conductivity.

(Specific resistance)
The specific resistance of the Sn—Zn—O-based oxide sintered body according to the embodiment of the present invention is 1 Ω·cm or less. Conventionally, the specific resistance of the Sn—Zn—O oxide sintered body is a very high value of 1×10 ⁶ Ω·cm or more. The Sn-Zn-O-based oxide sintered body according to the embodiment of the present invention has a low specific resistance value by containing a predetermined amount of the second additive element Ta.

(Relative density)
The relative density of the Sn—Zn—O-based oxide sintered body according to the embodiment of the present invention is 90% or more. The Sn—Zn—O-based oxide sintered body according to the embodiment of the present invention has a high relative density by containing the first additive element M in a predetermined amount.

(Black dot evaluation method)
Here, a method for evaluating the surface of the oxide sintered body will be described. For the evaluation of the black spots, after the firing step, the outer shape processing, the circumference processing and the surface grinding processing were performed to evaluate the oxide sintered body processed into a desired shape. FIG. 2 is a photograph showing a state of the surface of the Sn—Zn—O-based oxide sintered body according to the embodiment of the present invention. In FIG. 2, a ruler having a scale of 1 mm width is shown below the surface of the oxide sintered body. Then, coarse black dots with a diameter of about 2 mm can be confirmed at the locations shown by the arrows in the drawing. Also, a small black dot can be seen at the lower right of the coarse black dot. Although black dots are shown above and below the black dots in the drawing, these are markings shown in the photograph for confirming the position of the black dots.

In the present invention, the number of coarse black dots having a diameter of about 2 mm or more was counted. Then, the number of coarse black spots per 1 m ² was calculated from the total surface area of the oxide sintered body, and the coarse black spots were evaluated. For example, in the case of a cylindrical target oxide sintered body, the total surface area of the oxide sintered body is the sum of the areas of the outer peripheral surface, the inner peripheral surface, and both end surfaces.

<3. Sn-Zn-O-based oxide target>
An Sn—Zn—O-based oxide target (hereinafter, also referred to as “target”) according to an embodiment of the present invention was obtained by bonding a backing plate to the above-described Sn—Zn—O-based oxide sintered body. It is a Sn-Zn-O-based oxide target.

Since the target is composed of the Sn—Zn—O-based oxide sintered body described above, the characteristics of the oxide sintered body are inherited. That is, the target has high density and low resistance characteristics.

The target is obtained by bonding a backing plate to the Sn—Zn—O-based oxide sintered body described above. Specifically, the obtained oxide sintered body is subjected to outer shape processing, circumferential processing, and surface grinding processing to obtain a processed oxide sintered body having a desired shape, and Cu, Ti, A sputtering target can be obtained by adhering a backing plate made of stainless steel or the like with a bonding material. The preferred target shape is, but is not limited to, a rectangular or circular flat plate shape or a cylindrical shape.

The Sn—Zn—O-based oxide sintered body according to an embodiment of the present invention containing Zn and Sn as main components obtained under such conditions has a high density and has improved conductivity. It is possible to form a film by DC sputtering. Further, since no special manufacturing method is used, it can be applied to a cylindrical target.

Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples.

(Example 1)
In Example 1, SnO ₂ powder having an average particle size of 10 μm, ZnO powder having an average particle size of 10 μm, GeO ₂ powder having an average particle size of 20 μm as the first additional element M, and average particle size of 20 μm as the second additional element. Ta ₂ O ₅ powder was prepared.

Next, SnO ₂ powder and ZnO powder were mixed so that the atomic ratio Sn/(Sn+Zn) of Sn and Zn was 0.5, and the atomic ratio Ge of the first additive element M was Ge/(Sn+Zn+Ge+Ta). Was 0.001 and the atomic ratio Ta/(Sn+Zn+Ge+Ta) of the second additive element Ta was 0.006, and GeO ₂ powder and Ta ₂ O ₅ powder were prepared.

Then, Ta ₂ O ₅ powder is made into a slurry by combining pure water and a dispersant with Ta ₂ O ₅ powder by using a bead mill device (LMZ type manufactured by Ashizawa Finetech Co., Ltd.) in which hard ZrO ₂ balls are put, This was wet-milled. The particle size distribution of the Ta ₂ O ₅ powder after the wet pulverization was measured with a laser diffraction particle size distribution analyzer (manufactured by Shimadzu Corporation, SALD-2200). Then, wet pulverization was performed until D90 of Ta ₂ O ₅ powder became 5.0 μm.

Then, the raw material powder other than the prepared Ta ₂ O ₅ powder, pure water, an organic binder, and a dispersant were mixed in a mixing tank so that the raw material powder concentration was 60% by mass. To this slurry, wet-milled tantalum slurry was combined and mixed.

Next, using a bead mill (LMZ type manufactured by Ashizawa Finetech Co., Ltd.) in which hard ZrO ₂ balls were charged, wet milling was performed until the average particle diameter of the raw material powder became 1 μm or less, and then 10 hours. The above mixture was stirred to obtain a slurry. A laser diffraction particle size distribution measuring device (SALD-2200 manufactured by Shimadzu Corporation) was used to measure the average particle size of the raw material powder.

Next, the obtained slurry was sprayed and dried with a spray dryer device (Okawahara Kakoki Co., Ltd., ODL-20 type) to obtain granulated powder.

Next, the obtained granulated powder was filled into a cylindrical rubber mold, and molded by applying a pressure of 294 MPa (3 ton/cm ² ) with a cold isostatic press, and the obtained outer diameter was about 200 mm and inner diameter was about 200 mm. A compact having a size of 160 mm and a height of about 310 mm was put into a normal pressure sintering furnace, and air (oxygen concentration 21% by volume) was introduced into the sintering furnace up to 700°C. After confirming that the temperature in the sintering furnace reached 700°C, oxygen was introduced so that the oxygen concentration became 80% by volume, the temperature was raised to 1400°C, and the temperature was maintained at 1400°C for 15 hours.

After the holding time was completed, introduction of oxygen was stopped and cooling was performed to obtain a Sn—Zn—O-based oxide sintered body.

Next, the Sn—Zn—O-based oxide sintered body was processed into an outer diameter of 153 mm, an inner diameter of 135 mm, and a height of 238 mm by using a surface grinder, a gliding center, and a cylindrical grinder to form a desired shape. The obtained Sn-Zn-O-based oxide sintered body was obtained.

The number of black dots on the surface of the obtained oxide sintered body having a diameter of 2 mm or more was visually counted. When the number of black dots was counted for four oxide sintered bodies, the number of black dots having a diameter of 2 mm or more was two in all four oxide sintered bodies. When the surface area of the oxide sintered body was calculated from the outer peripheral surface, the inner peripheral surface, and the upper and lower end surfaces, the total surface area of the four oxide sintered bodies was about 0.89 m ² . Then, the number of black spots having a diameter of 2 mm or more per 1 m ^{2 of the} oxide sintered body was calculated and found to be 2.2 pieces/m ² .

A cylindrical backing plate made of stainless steel was bonded to the Sn—Zn—O-based oxide sintered body processed into a desired shape with an indium-based low melting point solder to obtain a cylindrical sputtering target. The cylindrical target obtained as described above was attached to a magnetron type rotary cathode sputtering device, sputtering was performed under a condition of a power density of 15 kW/m in an argon atmosphere of 0.7 Pa and continuously discharged for 3 hours. Never happened. The arcing during sputtering was performed by setting the detection time of the high-speed arc and the low-speed arc to 0, and visually counting the number of arcing occurrences per 10 minutes after 1 hour has elapsed from the start of sputtering. is there.

(Example 2)
In Example 2, an oxide sintered body according to Example 2 was obtained in the same manner as in Example 1 except that the Ta ₂ O ₅ powder was pulverized until D90 became 1.0 μm. As in Example 1, when the number of black dots having a diameter of 2 mm or more was counted for four oxide sintered bodies, the number of black dots having a diameter of 2 mm or more was 1 in all the four oxide sintered bodies. The number of black dots having a diameter of 2 mm or more was 1.1/m ² per 1 m ^{2 of the} oxide sintered body. Moreover, arcing did not occur.

(Comparative Example 1)
In Comparative Example 1, Ta ₂ O ₅ powder having a D90 of 10 μm was prepared as the second additive element, and pulverization before compounding was not performed. An oxide sintered body according to Comparative Example 1 was obtained in the same manner as in Example 1 except for the above. As in Example 1, when the number of black dots having a diameter of 2 mm or more was counted for the four oxide sintered bodies, the number of black dots having a diameter of 2 mm or more was 5 in the entire four oxide sintered bodies. The number of black spots having a diameter of 2 mm or more per 1 m ^{2 of the} oxide sintered body was 5.6/m ² . In addition, the occurrence of arcing was confirmed.

(Comparative example 2)
In Comparative Example 2, Ta ₂ O ₅ powder having a D90 of 25 μm was prepared as the second additive element, and pulverization before compounding was not performed. An oxide sintered body according to Comparative Example 1 was obtained in the same manner as in Example 1 except for the above. As in Example 1, when the number of black dots having a diameter of 2 mm or more was counted for four oxide sintered bodies, the number of black dots having a diameter of 2 mm or more was 38 in the entire four oxide sintered bodies. The number of black spots having a diameter of 2 mm or more was 43.0 pieces/m ² per 1 m ^{2 of the} oxide sintered body. In addition, the occurrence of arcing was confirmed.

(Comparative example 3)
Comparative Example 3 was carried out in the same manner as in Example 1 except that the GeO ₂ powder was pulverized in advance of the Ta ₂ O ₅ powder until the D90 was 5.0 μm before the raw material powder was prepared. The target according to No. 3 was obtained. Similar to Example 1, when the number of black dots having a diameter of 2 mm or more was counted for four oxide sintered bodies, the number of black dots having a diameter of 2 mm or more in the entire four oxide sintered bodies was 36. The number of black spots having a diameter of 2 mm or more was 40.4/m ² per 1 m ^{2 of the} oxide sintered body. In addition, the occurrence of arcing was confirmed.

Table 1 shows D90 of Ta ₂ O ₅ powder and GeO ₂ powder in Examples 1 and 2 and Comparative Examples 1 to 3, the number of black spots per 1 m ^{2 of} the target, and the presence or absence of arcing.

In Table 1, ◯ indicates that arcing was not confirmed, and x indicates that arcing was confirmed. As described above, when the second additive element Ta is added at a predetermined value or more, the occurrence of arcing becomes remarkable, but from Table 1, it can be seen that by setting D90 of Ta ₂ O ₅ powder to 5.0 μm or less, It was found that the number can be set to 3/m ² or less and the occurrence of arcing can be suppressed. Further, by controlling D90 of the second additive element Ta of the additive elements M and Ta, which are additive elements, the number of black dots can be reduced to 3 pieces/m ² or less, and arcing can be achieved. It was found that the occurrence of

Since the Sn—Zn—O-based oxide sintered body according to the present invention has characteristics such as high density and low resistance in addition to mechanical strength, sputtering for forming a transparent electrode such as a solar cell or a touch panel. It has industrial applicability to be used as a target.

Although one embodiment and each example of the present invention have been described in detail as above, it is understood by those skilled in the art that many modifications are possible without materially departing from the novel matters and effects of the present invention. , You can easily understand. Therefore, such modifications are all included in the scope of the present invention.

For example, a term described in the specification or the drawings at least once together with a different term having a broader meaning or the same meaning can be replaced with the different term anywhere in the specification or the drawing. In addition, the manufacturing method of the Sn-Zn-O-based oxide sintered body, the configuration of the Sn-Zn-O-based oxide sintered body, and the Sn-Zn-O-based oxide target are also one embodiment and each embodiment of the present invention. The present invention is not limited to the one described in the example, and various modifications can be made.

S1 granulation process, S2 molding process, S3 firing process

Claims (6)

In a method for producing a Sn—Zn—O-based oxide sintered body containing zinc (Zn) and tin (Sn) as main components,
A granulating step of mixing the zinc oxide powder, the tin oxide powder, the oxide powder containing the first additional element M and the tantalum oxide powder to produce a granulated powder;
A molding step of pressure-molding the granulated powder to obtain a molded body,
And a firing step of firing the molded body to obtain an oxide sintered body,
The first additive element M is at least one selected from Si, Ti, Ge, In, Bi, Ce, Al and Ga,
The tantalum oxide powder has a D90 of 5 μm or less, wherein the Sn-Zn-O-based oxide sintered body is manufactured. The Sn—Zn—O-based oxide according to claim 1, wherein the firing step is performed at a temperature of 1200° C. or more and 1450° C. or less for 10 hours or more and 30 hours or less in an atmosphere having an oxygen concentration of 70% by volume or more. Manufacturing method of sintered body. The method for producing an Sn-Zn-O-based oxide sintered body according to claim 1 or 2, wherein the tantalum oxide powder is a powder obtained by performing wet pulverization. In a Sn—Zn—O-based oxide sintered body containing zinc (Zn) and tin (Sn) as main components,
Further, containing the first additional element M and tantalum (Ta),
The tin is contained in an atomic number ratio Sn/(Sn+Zn) of 0.1 or more and 0.9 or less,
The first additive element M is at least one selected from Si, Ti, Ge, In, Bi, Ce, Al and Ga,
The first additive element M is contained in a ratio of 0.0001 or more and 0.04 or less as an atomic ratio M/(Sn+Zn+M+Ta) with respect to the total amount of all metal elements,
The Ta is contained in a ratio of 0.005 or more and 0.1 or less as an atomic ratio Ta/(Sn+Zn+M+Ta) with respect to the total amount of all metal elements,
The Sn-Zn-O-based oxide sintered body is characterized in that on the surface of the oxide sintered body, there are 3 black spots/m ² or less having a diameter of 2 mm or more. The Sn-Zn-O-based oxide sintered body according to claim 4, wherein the relative density is 90% or more and the specific resistance is 1 Ω·cm or less. An Sn-Zn-O-based oxide target obtained by bonding a backing plate to the Sn-Zn-O-based oxide sintered body according to claim 4.