WO2021172428A1 - Oxide sputtering target, and production method for oxide sputtering target - Google Patents

Abstract

An oxide sputtering target according to the present invention has a cylindrical shape and comprises an oxide containing zirconium, silicon, and indium as metal components, wherein the variation in the density of the cylindrical shape in the axial direction is less than 3%.

Description

Oxide sputtering target and manufacturing method of oxide sputtering target

The present invention relates to an oxide sputtering target having a cylindrical shape and composed of an oxide containing zirconium, silicon and indium as metal components, and a method for producing the oxide sputtering target.
The present application claims priority based on Japanese Patent Application No. 2020-031509 filed in Japan on February 27, 2020, the contents of which are incorporated herein by reference.

In a display panel such as a liquid crystal display, an organic EL display, and a touch panel, a shield layer is provided in order to prevent malfunction due to charging of the liquid crystal element, the organic EL element, or the like. In particular, in an in-cell type touch panel, the shield layer described above is also required to have an action of allowing a touch signal to reach a sensor portion inside the panel while eliminating noise from the outside.
Further, in this shield layer, in order to ensure the visibility of the display panel, it is also required to have high transparency of visible light.

Here, for example, in Patent Document 1, a transparent conductive film containing indium tin oxide (ITO) as a main component is proposed as the above-mentioned shield layer.
By the way, in a transparent conductive film containing indium tin oxide (ITO) as a main component, since the transmittance in visible light is low, it may appear yellowish and the visibility may be deteriorated. rice field.

Therefore, it is conceivable to apply an oxide film containing zirconium, silicon and indium as a metal component as the shield layer described above.
For example, Patent Documents 2 to 4 propose an oxide sputtering target used for forming an oxide film containing zirconium, silicon, and indium as a metal component.

Japanese Unexamined Patent Publication No. 2013-142194 Japanese Unexamined Patent Publication No. 2007-327103 Japanese Unexamined Patent Publication No. 2009-062585 Japanese Unexamined Patent Publication No. 2018-040032

By the way, the oxide sputtering targets disclosed in Patent Documents 2 to 4 are mainly intended to form a dielectric layer and a protective layer of an optical disk which is an information recording medium, and the target sputtering surfaces are compared. It was a small one.
Here, when forming a shield layer such as an in-cell type touch panel, it is preferable to use a large sputtering target or a cylindrical sputtering target having a large area of the target sputtering surface.

In Patent Documents 2 to 4 described above, when the cylindrical sputtering target is manufactured, the pressurized state in the axial direction is different, so that the firing is insufficient and the density varies in the axial direction. There is a problem that cracks are likely to occur during bonding or sputtering. In addition, the sputter rate may vary in the axial direction, resulting in a decrease in usage efficiency. Therefore, in Patent Documents 2 to 4, there is a possibility that sputter film formation cannot be stably performed.

The present invention has been made in view of the above circumstances, and is an oxide sputtering target capable of stably performing sputtering deposition even with a cylindrical sputtering target, and the oxide sputtering target. It is an object of the present invention to provide the manufacturing method of.

In order to solve the above problems, the oxide sputtering target according to one aspect of the present invention is an oxide sputtering target having a cylindrical shape and composed of an oxide containing zirconium, silicon and indium as metal components. It is characterized in that the variation in density in the axial direction of the cylindrical shape is within 3%.

According to the oxide sputtering target of the present invention, since it is composed of an oxide containing zirconium, silicon and indium as a metal component, it has high resistance and excellent visible light transmission, and is suitable for a shield layer. It is possible to form an oxide film.
Since the variation in density of the cylindrical shape in the axial direction is within 3%, the occurrence of cracks during bonding and sputtering can be suppressed, and the variation in sputter rate in the axial direction can be suppressed. .. Therefore, it is possible to stably perform sputter film formation.

Here, in the oxide sputtering target of the present invention, it is preferable that the variation of the specific resistance in the axial direction of the cylindrical shape is within 10%.
In this case, since the variation of the specific resistance in the axial direction of the cylindrical shape is within 10%, the sputtering is stable on the entire target sputtering surface forming the cylindrical surface, and the occurrence of abnormal discharge during sputtering can be suppressed. can.

Further, in the oxide sputtering target of the present invention, the hole formed on the outer peripheral surface preferably has a diameter of less than 0.5 mm.
In this case, since no holes having a diameter of 0.5 mm or more are observed on the outer peripheral surface of the target as the sputtering surface, it is possible to suppress the occurrence of abnormal discharge during sputtering.

Further, in the oxide sputtering target of the present invention, the total metal component is 100 mass%, the Zr content is within the range of 2 mass% or more and 27 mass% or less, and the In content is within the range of 65 mass% or more and 95 mass% or less. , Si content is preferably in the range of 0.5 mass% or more and 15 mass% or less, and unavoidable impurity metal elements are contained in addition to the zirconium, the indium, and the silicon.
In this case, since the metal component is defined as described above, an oxide film having excellent durability, conductivity, and visibility can be formed.

Further, in the oxide sputtering target of the present invention, the specific resistance value is preferably 1.0 × 10 ^-2 Ω · cm or less.
In this case, since the specific resistance value is 1.0 × 10 ^-2 Ω · cm or less, it is conductive and can suppress the occurrence of abnormal discharge during sputtering.

The method for producing an oxide sputtering target according to one aspect of the present invention is a method for producing an oxide sputtering target composed of an oxide having a cylindrical shape and containing zirconium, silicon and indium as metal components. A raw material slurry production step of mixing powder, silicon oxide powder and indium oxide powder, adding a binder to form a slurry, and a drying step of drying the raw material slurry by a spray-drying method to obtain a sintered raw material powder are obtained. A molding step of filling a rubber mold in which a core metal is arranged to obtain a cylindrical molded body by a cold isotropic pressure method, and a degreasing step of removing the binder from the molded body. It is characterized by comprising a sintering step of sintering the degreased molded body in an oxygen atmosphere to obtain a sintered body.

According to the method for producing an oxide sputtering target having this configuration, a raw material slurry generation step of mixing zirconium oxide powder, silicon oxide powder and indium oxide powder with an aqueous solvent and adding a binder to form a slurry, and this raw material slurry Is provided with a drying step of obtaining a sintered raw material powder by a spray-drying method, so that a cylindrical molded body can be molded relatively easily in a subsequent molding step. Further, since the degreasing step of removing the binder from the molded product is provided, it is possible to prevent the binder from inhibiting sintering.
Then, in the molding step, the obtained sintered raw material powder is filled in a rubber mold using a core metal, and a cylindrical molded body is molded by a cold isotropic pressure method, which is sufficient. It is possible to apply a high pressure to the surface, and it is possible to suppress variations in density in the axial direction.

Here, in the method for producing an oxide sputtering target of the present invention, it is preferable that the density variation in the axial direction of the cylindrical molded body is within 3%.
In this case, in the molded product obtained in the molding step, the variation in density in the axial direction is suppressed within 3%, so that the occurrence of cracks in the sintering step can be suppressed.

Further, in the method for producing an oxide sputtering target of the present invention, it is preferable to add wax in the raw material slurry generation step.
In this case, since the wax is added together with the binder in the raw material slurry generation step, the wax softens and melts at an early stage and moves to the outside of the molded product in the subsequent degreasing step, and the route to the outside of the binder. Is ensured, and it becomes possible to promote the removal of the binder. Thereby, the generation of holes due to the remaining binder can be suppressed.

Further, in the method for producing an oxide sputtering target of the present invention, it is preferable that the core metal is subjected to a surface smoothing treatment.
In this case, the molded body can be relatively easily removed from the core metal after the molding step. Therefore, it is possible to suppress the occurrence of cracks in the molded product.

Further, in the method for producing an oxide sputtering target of the present invention, it is preferable that the arithmetic average roughness Ra of the surface of the core metal is 1.6 μm or less.
In this case, the molded body can be relatively easily removed from the core metal after the molding step. Therefore, it is possible to suppress the occurrence of cracks in the molded product.

Further, in the method for producing an oxide sputtering target of the present invention, it is preferable that the Vickers hardness of the core metal is 180 Hv or more.
In this case, since the deformation of the core metal can be suppressed after the molding step, the molded body can be relatively easily removed from the core metal. Therefore, it is possible to suppress the occurrence of cracks in the molded product.

Further, in the method for producing an oxide sputtering target of the present invention, the pressurizing pressure in the molding step is preferably 100 MPa or more.
In this case, since the molded body is sufficiently pressurized, it is possible to improve the density of the sintered body. In addition, the specific resistance can be reduced.

According to the present invention, it is possible to provide an oxide sputtering target capable of stably performing sputtering deposition even with a cylindrical sputtering target, and a method for manufacturing the oxide sputtering target.

It is the schematic explanatory drawing of the oxide sputtering target which concerns on one Embodiment of this invention. It is the schematic explanatory drawing of the oxide sputtering target which concerns on one Embodiment of this invention. It is a flow chart which shows the manufacturing method of the oxide sputtering target which concerns on one Embodiment of this invention.

Hereinafter, the oxide sputtering target 10 according to the embodiment of the present invention and the method for producing the oxide sputtering target 10 will be described with reference to the attached drawings.
The oxide sputtering target 10 according to the present embodiment forms an oxide film suitable as a shield layer arranged for antistatic purposes in a liquid crystal display panel, an organic EL display panel, and a display panel such as a touch panel. It is used when doing so.

The oxide sputtering target 10 according to the present embodiment is composed of an oxide containing zirconium, silicon, and indium as a metal component. The oxide sputtering target 10 of the present embodiment has a composite oxide phase containing at least a part of the above-mentioned metal elements and an indium oxide phase.
In the present embodiment, the total metal component is 100 mass%, the zirconium (Zr) content is in the range of 2 mass% or more and 27 mass% or less, and the indium (In) content is in the range of 65 mass% or more and 95 mass% or less. Among them, the content of silicon (Si) is preferably in the range of 0.5 mass% or more and 15 mass% or less, and unavoidable impurity metal elements may be contained in addition to zirconium, indium, and silicon. Examples of the composite oxide phase in the oxide sputtering target 10 include In ₂ Si ₂ O ₇ .

As shown in FIGS. 1A and 1B, the oxide sputtering target 10 according to the present embodiment is a cylindrical sputtering target having a cylindrical surface (outer peripheral surface) as a sputtering surface.
The oxide sputtering target 10 shown in FIGS. 1A and 1B has a cylindrical shape extending along the axis O. For example, the outer diameter D is within the range of 140 mm ≦ D ≦ 200 mm, and the inner diameter d is 100 mm ≦ d ≦. Within the range of 180 mm, the length L in the axis O direction is within the range of 80 mm ≦ L ≦ 350 mm.

In the oxide sputtering target 10 according to the present embodiment, the density variation in the axial direction of the cylindrical shape is set to 3% or less.
In this embodiment, it is preferable that the average value (average density) of the densities measured at a plurality of points is 5.5 g / cm ^{3 or more.}
Further, in the oxide sputtering target 10 according to the present embodiment, it is preferable that holes (recesses, through holes) having a diameter of 0.5 mm or more are not observed on the outer peripheral surface to be the sputtering surface. That is, it is preferable that all the holes formed on the outer peripheral surface have a diameter of less than 0.5 mm.

Further, in the oxide sputtering target 10 according to the present embodiment, it is preferable that the variation of the specific resistance in the axial direction of the cylindrical shape is within 10%.
In this embodiment, it is preferable that the average value (average resistivity) of the specific resistances measured at a plurality of points is 1.0 × 10 ^-2 Ω · cm or less.

Hereinafter, in the oxide sputtering target 10 of the present embodiment, the oxide composition, phase composition, variation in density in the axial direction, variation in resistivity in the axial direction, and holes having a diameter of 0.5 mm or more are described as described above. Show the specified reason.

(Oxide composition)
The oxide sputtering target 10 of the present embodiment is composed of an oxide containing zirconium, silicon, and indium as a metal component. In the oxide sputtering target 10 having such a composition, it is possible to form an oxide film having a sufficiently high resistance value and excellent transparency of visible light.
Here, in the present embodiment, assuming that the total of the metal components is 100 mass%, the Zr content is in the range of 2 mass% or more and 27 mass% or less, the In content is in the range of 65 mass% or more and 95 mass% or less, and Si. It is preferable that the content is in the range of 0.5 mass% or more and 15 mass% or less, and that the content is an unavoidable impurity metal element.

When the Zr content is 2 mass% or more, the durability of the formed oxide film can be improved, the hardness becomes hard, and the scratch resistance becomes strong. On the other hand, when the Zr content is 27 mass% or less, the increase in the refractive index can be suppressed and the occurrence of unnecessary reflection can be suppressed, so that the decrease in the transmittance of visible light can be suppressed.
The total of the metal components is 100 mass%, the lower limit of the Zr content is preferably 5 mass% or more, and the upper limit of the Zr content is preferably 20 mass% or less.

When the In content is 65 mass% or more, the conductivity of the oxide sputtering target 10 can be ensured, and an oxide film can be formed by direct current (DC) sputtering. On the other hand, when the In content is 95 mass% or less, it is possible to suppress a decrease in the transmittance of short wavelengths and ensure visibility.
The total of the metal components is 100 mass%, the lower limit of the In content is preferably 75 mass% or more, and the upper limit of the In content is preferably 90 mass% or less.

When the Si content is 0.5 mass% or more, the flexibility of the oxide sputtering target 10 can be ensured and the crack resistance of the film is improved. On the other hand, when the Si content is 15 mass% or less, it is possible to suppress a decrease in the conductivity of the film, and it is possible to form an oxide film by direct current (DC) sputtering.
The total of the metal components is 100 mass%, the lower limit of the Si content is preferably 2 mass% or more, and the upper limit of the Si content is preferably 7 mass% or less.

(Phase composition)
The oxide sputtering target 10 of the present embodiment has a composite oxide phase containing at least a part of the above-mentioned metal elements and an indium oxide phase.
Here, the presence of the indium oxide phase lowers the resistance value of the oxide sputtering target 10 of the present embodiment, and makes it possible to form an oxide film by direct current (DC) sputtering.

(Variation of density in the axial direction)
In the cylindrical sputtering target, the pressurized state differs in the axial direction (axis O direction) at the time of manufacturing, the firing becomes insufficient, and the density tends to vary. Here, if the density varies in the axial direction of the cylindrical shape, cracks may easily occur during bonding or spattering. In addition, the sputter rate may vary in the axial direction.
Therefore, in the present embodiment, the variation in density in the axial direction of the cylindrical shape is set to 3% or less.
In this embodiment, the density variation is defined by the following formula from the maximum and minimum values of the densities measured at a plurality of points.
Density variation = (maximum value-minimum value) / (maximum value + minimum value) x 100 (%)

Here, as shown in FIG. 1, the variation in the density of the oxide sputtering target 10 is obtained at an arbitrary plurality of locations (for example, in the circumferential direction of the sputtering surface) at both end portions A and B in the axial direction O direction and the central portion C. In this embodiment, the average values of (1), (2), (3), and (4) at intervals of 90 ° in the circumferential direction of the sputter surface are calculated, respectively, and both ends A and B are calculated. And the density of the central portion C was used, and the variation in density in the axial direction was calculated.

In the oxide sputtering target 10 of the present embodiment, the average value (average density) of the density ^{is preferably 5.5 g / cm 3} or more, and 6.0 g / cm ³ or more. More preferably, it is 6.2 g / cm ³ or more.

(Variation of resistivity in the axial direction)
By suppressing the variation in resistivity in the axial direction of the cylindrical shape, it is possible to further suppress the occurrence of abnormal discharge during sputter film formation.
Therefore, in the present embodiment, the variation of the specific resistance in the axial direction of the cylindrical shape is preferably 10% or less, and more preferably 7% or less.

In this embodiment, the variation in resistivity is defined by the following formula from the maximum and minimum values of resistivity measured at a plurality of points.
Variation in resistivity = (maximum value-minimum value) / (maximum value + minimum value) x 100 (%)

Here, as shown in FIGS. 1A and 1B, the variation in the specific resistance of the oxide sputtering target 10 is an arbitrary plurality of variations in the circumferential direction of the sputtering surface at both end portions A and B in the axial direction O direction and the central portion C. For example, in the present embodiment, the average value of each of the four points (4 points (1), (2), (3), and (4) at 90 ° intervals in the circumferential direction of the sputter surface) is calculated, and both ends. The variation of the specific resistance in the axial direction was calculated by using the densities of A, B and the central portion C as the densities.

In the oxide sputtering target 10 of the present embodiment, the average value of the specific resistance (average specific resistance) is preferably 1.0 × 10 ⁻² Ω · cm or less, preferably 8.5 × 10. more preferably not more than ^{-3 Ω} · cm, more preferably not more than 7.5 × ^{10 -3 Ω} · cm.

(Hole on the outer circumference)
In the oxide sputtering target 10 of the present embodiment, when a hole having a diameter of 0.5 mm or more is not observed, it is possible to further suppress the occurrence of abnormal discharge during sputtering film formation due to the hole.
Therefore, in the present embodiment, it is preferable that holes having a diameter of 0.5 mm or more are not observed on the outer peripheral surface to be the sputter surface.
In the present embodiment, the presence or absence of holes having a diameter of 0.5 mm or more is confirmed by visually observing the outer peripheral surface of the oxide sputtering target 10.

Next, the method for manufacturing the oxide sputtering target 10 according to the present embodiment described above will be described with reference to FIG.

(Raw Material Slurry Generation Step S01)
First, zirconium oxide powder (ZrO ₂ powder), silicon oxide powder (SiO ₂ powder) and indium oxide powder (In ₂ O ₃ powder) are prepared.
Here, the zirconium oxide powder (ZrO ₂ powder), the silicon oxide powder (SiO ₂ powder), and the indium oxide powder (In ₂ O ₃ powder) each have a purity of 99.9% by mass or more and an average particle diameter of 0. It is preferably in the range of 1 μm or more and 20 μm or less. Incidentally, the purity of ZrO ₂ powder as the metal component, Fe, Si, Ti, the content of Na was measured, with the balance was calculated as being Zr. _{The ZrO 2} powder of the present embodiment may contain up to 2.5% of _{HfO 2.}

These oxide powders were weighed so as to have a predetermined composition ratio, and wet pulverized and mixed with an aqueous solvent to which a dispersant was added using a ball mill device or a bead mill device using zirconia balls as a pulverizing medium.
A binder and wax were added to the obtained mixture and dispersed by a stirrer to generate a raw material slurry.

Here, as the dispersant, for example, polycarboxylic acid, naphthalene / sulfonic acid and the like can be used.
Further, as the binder, for example, polyvinyl alcohol (PVA), polyacrylamide, acrylic resin and the like can be used.
Further, as the wax, for example, paraffin, microcrystallin and the like can be used.

(Drying step S02)
Next, the obtained raw material slurry is dried by a spray-drying method to obtain a sintered raw material powder. Here, the sintered raw material powder is preferably classified to 250 μm or less. By using this sintered raw material powder, pressure molding becomes possible.

(Molding step S03)
Next, the obtained sintered raw material powder is filled in a rubber mold in which a core metal is arranged, and a cylindrical molded body is obtained by a cold isotropic pressure method. The pressurizing pressure in the molding step S03 is preferably 100 MPa or more.
Here, if the molded body is strongly adhered to the core metal and it is difficult to release the mold, the molded body may be cracked. Therefore, it is preferable to use a core metal whose surface is smoothed by forming hard Cr plating on the surface of carbon steel, for example. Further, it is preferable that the arithmetic average roughness Ra of the surface of the core metal is 1.6 μm or less. Further, it is preferable that the Vickers hardness of the core metal is 180 Hv or more. It is preferable to dispose a mold release agent such as BN on the surface of the core metal.
Further, in the present embodiment, it is preferable that the density variation in the axial direction of the obtained cylindrical molded product is within 3%.

(Degreasing step S04)
Next, the molded body is heated to perform degreasing. In this degreasing step S04, heating is performed at a heating rate of 10 ° C./h or more and 100 ° C./h or less, and the temperature is maintained at 350 ° C. or more and 450 ° C. or less for 10 hours, and then to 500 ° C. or more and 600 ° C. or less. It is preferable to heat and hold for 10 hours. As a result, gas is slowly generated and the formation of holes is suppressed.
Further, since the wax is added, the wax softens and melts at an early stage and moves to the outside of the molded product during heating, so that a path to the outside of the binder is secured.

(Sintering step S05)
This molded product is placed in a firing device having an oxygen introduction function, heated while introducing oxygen, and sintered. That is, sintering is performed in an oxygen atmosphere.
At this time, the amount of oxygen introduced is preferably in the range of 3 L / min or more and 10 L / min or less. The rate of temperature rise is preferably in the range of 50 ° C./h or more and 200 ° C./h or less.

Then, in the present embodiment, in the sintering step S05, it is preferable to spread the powder under the molded product. By using the bedding powder, friction during sintering shrinkage can be reduced, and cracking during sintering can be suppressed.
As the bedding powder, one that does not melt at the time of heating and does not react with the molded product can be applied, and in the present embodiment, one of the melted zirconia powder (42-100 mesh) was used.

In the sintering step S05, the molded product is sintered by holding it in a temperature range of 1200 ° C. or higher and 1400 ° C. or lower for 3 hours or longer, and then heating and holding it to a temperature exceeding 1400 ° C. (for example, 1500 ° C. or higher). To proceed.
Hold for 3 hours or more in a temperature range of 1200 ° C. or higher, which is the temperature at which sintering of the indium oxide powder in the sintering raw material powder is started, and 1400 ° C. or lower, at which sintering proceeds due to the formation of the composite oxide. As a result, oxygen gas can be uniformly permeated into the molded body while maintaining the gap channels between the sintered raw material powders during sintering. The upper limit of the holding time in the temperature range of 1200 ° C. or higher and 1400 ° C. or lower is not limited, but is preferably 15 hours or less from the viewpoint of work efficiency.
After that, by heating and holding the molded product to a temperature exceeding 1400 ° C., the sintering of the molded product proceeds uniformly.

(Machining process S06)
Next, the above-mentioned sintered body is subjected to machining such as lathe processing to obtain an oxide sputtering target 10 having a predetermined size.

The oxide sputtering target 10 of the present embodiment is manufactured by the above-mentioned process.

Then, by performing a sputtering film formation using the oxide sputtering target 10 of the present embodiment, an oxide film suitable as a shield layer for an in-cell type touch panel or the like is formed.
Here, in the oxide sputtering target 10 of the present embodiment, as described above, the resistance value is low due to the presence of the indium oxide phase, and the oxide film can be formed by direct current (DC) sputtering. It becomes.
On the other hand, the formed oxide film has a composite oxide phase as a whole and has a sufficiently high resistance value, which is particularly suitable as a shield layer. Examples of the composite oxide phase in the oxide film include In ₂ Si ₂ O ₇ .

According to the oxide sputtering target 10 of the present embodiment having the above configuration, since it is composed of an oxide containing zirconium, silicon and indium as a metal component, the resistance value is high and the resistance value is high. It has excellent visible light transmittance and makes it possible to form an oxide film suitable for the shield layer.

Further, in the present embodiment, since the variation in the density of the cylindrical shape in the axial direction is within 3%, the occurrence of cracks during bonding and sputtering can be suppressed, and the variation in the sputter rate in the axial direction can be suppressed. It can be suppressed. Therefore, it is possible to stably perform sputter film formation.

Further, in the present embodiment, when the variation of the specific resistance in the axial direction of the cylindrical shape is within 10%, the sputtering is stabilized on the entire target sputtering surface forming the cylindrical surface, and abnormal discharge occurs during the sputtering. Can be suppressed.
Further, in the present embodiment, when the specific resistance value is 1.0 × 10 ^-2 Ω · cm or less, it is conductive and can suppress the occurrence of abnormal discharge during sputtering.

Further, in the present embodiment, when a hole having a diameter of 0.5 mm or more is not observed on the outer peripheral surface to be the sputter surface, it is possible to suppress the occurrence of abnormal discharge during sputtering, and more stably sputter film formation can be performed. conduct.

According to the method for producing an oxide sputtering target according to the present embodiment, the raw material slurry generation step S01 in which zirconium oxide powder, silicon oxide powder and indium oxide powder are mixed with an aqueous solvent and a binder is added to form a slurry, Since this raw material slurry is dried by a spray-drying method to obtain a sintered raw material powder, a drying step S02 is provided, so that a cylindrical molded body can be molded relatively easily in the subsequent molding step S03. It becomes. Further, since the degreasing step S04 for removing the binder from the molded product is provided, it is possible to prevent the binder from inhibiting sintering.
Then, in the molding step S03, the obtained sintered raw material powder is filled in a rubber mold using a core metal, and a cylindrical molded body is molded by a cold isotropic pressure method, which is sufficient. It is possible to apply a high pressure to the surface, and it is possible to suppress variations in density in the axial direction.

In the present embodiment, in the molded product obtained in the molding step S03, when the variation in density in the axial direction is suppressed within 3%, the occurrence of cracks in the subsequent sintering step S05 can be suppressed. It will be possible.

Further, in the present embodiment, when the wax is added together with the binder in the raw material slurry generation step S01, the wax is prematurely softened and melted and moved to the outside of the molded product in the subsequent degreasing step S04. A route to the outside of the binder is secured, and it becomes possible to promote the removal of the binder. Thereby, the generation of holes due to the remaining binder can be suppressed.

Further, in the present embodiment, when the core metal used in the molding step S03 is subjected to a surface smoothing treatment, the molded body can be relatively easily removed from the core metal after the molding step S03. .. Therefore, it is possible to suppress the occurrence of cracks in the molded product.
Further, even when the arithmetic mean roughness Ra of the surface of the core metal is 1.6 μm or less, the molded body can be removed from the core metal relatively easily, and cracks in the molded body occur. Can be suppressed.
Further, even when the Vickers hardness of the core metal is 180 Hv or more, the molded body can be removed from the core metal relatively easily, and the occurrence of cracks in the molded body can be suppressed.

Further, in the present embodiment, when the pressurizing pressure in the molding step S03 is 100 MPa or more, the molded product is sufficiently pressurized, so that the density of the sintered body can be improved. In addition, the specific resistance can be reduced.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the invention.

The results of the confirmation experiment conducted to confirm the effectiveness of the present invention will be described below.

<Oxide sputtering target>
As raw material powders, indium oxide powder (In ₂ O ₃ powder: purity 99.9% by mass or more, average particle size 1 μm) and silicon oxide powder (SiO ₂ powder: purity 99.9% by mass or more, average particle size 2 μm) And zirconium oxide powder (ZrO ₂ powder: purity 99.9% by mass or more, average particle size 2 μm) were prepared. Incidentally, the purity of ZrO ₂ powder as the metal component, Fe, Si, Ti, the content of Na was measured, with the balance was calculated as being Zr. _{The ZrO 2} powder of the present embodiment may contain up to 2.5% by mass of _{HfO 2.}
Then, these were weighed so as to have the compounding ratio shown in the table.

As shown in the table, each of the weighed raw material powders is subjected to a dispersant (a dispersant using a basket mill device using a zirconia ball having a diameter of 2 mm as a crushing medium or a bead mill device using a zirconia ball having a diameter of 0.5 mm as a crushing medium. Wet pulverization and mixing were carried out in an aqueous solvent containing (polycarboxylic acid).
A binder (polyvinyl alcohol) and wax (liquid paraffin) were added to the obtained mixture and dispersed by a stirrer to generate a raw material slurry.
This raw material slurry was dried, and zirconia balls were removed with a 250 μm sieve to obtain a sintered raw material powder. It was dried by spray drying and sieved to 250 μm to obtain a sintered raw material powder.

The obtained sintered raw material powder was filled in a rubber mold (outer diameter 205 mm, inner diameter 165 mm, height 200 mm) in which a core metal was arranged, and CIP (cold isotropic pressure pressurization method) molding was performed. The conditions for CIP molding were normal temperature (25 ° C.) and the pressurizing pressure shown in Table 1. In addition, the core metal shown in the table was used. In Comparative Example 2, the molded product was molded by the pressing method.

With respect to the obtained cylindrical molded body, the variation in density in the axial direction was measured. The measurement results are shown in Table 1.
The obtained molded product was held in an atmospheric furnace at a heating rate of 20 ° C./hr and an ultimate temperature of 350 ° C. for 10 hours, and then heated to an ultimate temperature of 600 ° C. and held for 10 hours to perform degreasing.

Then, the degreased molded product is placed in a firing device having an oxygen introduction function (internal volume of the device is 27,000 cm ³ ), heated while introducing oxygen, and sintered. At this time, the amount of oxygen introduced was 6 L / min. The rate of temperature rise was 120 ° C./h.
Then, when the temperature of the sintering was raised, the temperature was maintained at 1200 ° C. for 3 hours, and the main firing was performed at 1410 ° C. for 5 hours to obtain a sintered body.

The obtained sintered body was subjected to wet grinding to obtain a target having an outer diameter of 155 mm, an inner diameter of 135 mm, and a height of 150 mm. Four of these were used to make a cylindrical sputtering target with a length of 600 mm.

The obtained oxide sputtering target was evaluated for the following items. The evaluation results are shown in Table 2.

(Metal component composition)
A sample was cut out from the produced oxide sputtering target, pulverized, pretreated with an acid, and then the metal components of Zr, Si, and In were analyzed by ICP-AES. The content of each metal component relative to the content was calculated and shown in Table 2.

(Density and variation in density)
Place one end face of the cylindrical sputtering target on the lower side, and in a plane orthogonal to the axis, the X axis is the arbitrary end face direction, the Y axis is the end face direction that intersects the X axis perpendicularly, and the Z axis is the axis direction. When the center is (X, Y, Z) = (0 mm, 0 mm, 0 mm) coordinates, (-72.5 mm, 0 mm, -70 mm), (+ 72.5 mm, 0 mm, -70 mm), (0 mm,- 72.5mm, -70mm), (0mm, +72.5mm, -70mm), (-72.5mm, 0mm, 0mm), (+72.5mm, 0mm, 0mm), (0mm, -72.5mm, 0mm) , (0mm, +72.5mm, 0mm), (-72.5mm, 0mm, +70mm), (+72.5mm, 0mm, +70mm), (0mm, -72.5mm, +70mm), (0mm, +72.5mm, It was cut into blocks of 10 mm × 10 mm × 10 mm centered on each of 12 points (+70 mm). The dimensional density of the obtained 12 blocks of 10 mm × 10 mm × 10 mm was measured. Then, the average value of the densities of these 12 samples is shown in the table.
Regarding the variation in density, 12 blocks were divided into 4 sets including 3 blocks connected in the axial direction as one set. The density variation for each set was calculated from the average value, the maximum value, and the minimum value of the density by the following formula.
Density variation = (maximum value-minimum value) / average value × 100 (%) Then, the average value of the four sets of density variation was obtained and used as the density variation of the entire cylindrical sputtering target.

(Specific resistance and variation in specific resistance)
Twelve blocks similar to the sample for density measurement were measured by a four-probe method using a low resistivity meter (Loresta-GP) manufactured by Mitsubishi Chemical Corporation. The temperature at the time of measurement was 23 ± 5 ° C., and the humidity was 50 ± 20%. Then, the variation in resistivity was calculated in the same manner as the density. The average value of resistivity is shown in the table.

(Abnormal discharge, cracking)
The obtained oxide sputtering target was soldered to the backing tube using In solder, and mounted on a magnetron sputtering apparatus. Then, using Ar gas as the sputter gas by the magnetron sputtering device, the flow rate is 50 sccm, the pressure is 0.67 Pa, and the input power is 5 W / cm ² for 1 hour of sputtering, which is provided in the DC power supply device. The number of abnormal discharges was measured by the arc count function.
In addition, the oxide sputtering target after sputtering was visually observed to evaluate the presence or absence of cracks.

(Presence or absence of holes)
The outer peripheral surface of the target was visually observed, and the number of holes having a diameter of 0.5 mm or more was counted.

In Comparative Example 1 in which the sintered raw material powder was obtained without adding a binder, a cylindrical molded product could not be obtained in the molding step.
In Comparative Example 2 in which the molded product was formed by press molding, the variation in the density of the oxide sputtering target in the axial direction was as large as 5.1%. Therefore, cracking was confirmed during spattering.

On the other hand, in Examples 1 to 7 of the present invention, the variation in density in the axial direction was 3% or less, cracks were not confirmed during sputtering, and stable film formation was possible.
In Example 2 of the present invention to which no wax was added, five or more holes having a diameter of 0.5 mm or more were confirmed on the outer peripheral surface of the oxide sputtering target, and some abnormal discharges were observed, but at a level where there was no problem. there were.
In Example 3 of the present invention in which the pressurizing pressure during molding was 50 MPa, the density of the oxide sputtering target was slightly low, the specific resistance value was large, and some abnormal discharge was observed, but there was no problem. Met.
In Example 4 of the present invention in which the arithmetic average roughness Ra of the surface of the core metal was 3.2 μm and the Vickers hardness was 150 Hv without performing the surface smoothing treatment on the core metal, minute cracks were confirmed in the molded body. However, it was a level without problems.

From the above, according to the example of the present invention, there is provided an oxide sputtering target capable of stably performing sputtering deposition even with a cylindrical sputtering target, and a method for producing the oxide sputtering target. It was confirmed that it was possible.

Claims (12)

1. An oxide sputtering target consisting of an oxide having a cylindrical shape and containing zirconium, silicon, and indium as metal components.
   An oxide sputtering target characterized in that the variation in density in the axial direction of the cylindrical shape is within 3%.
2. The oxide sputtering target according to claim 1, wherein the variation in specific resistance in the axial direction of the cylindrical shape is within 10%.
3. The oxide sputtering target according to claim 1 or 2, wherein the hole formed on the outer peripheral surface of the cylindrical shape has a diameter of less than 0.5 mm.
4. Assuming that the total of the metal components is 100 mass%, the zirconium content is in the range of 2 mass% or more and 27 mass% or less, the indium content is in the range of 65 mass% or more and 95 mass% or less, and the silicon content is 0. The invention according to any one of claims 1 to 3, wherein the content is in the range of 5 mass% or more and 15 mass% or less, and contains an unavoidable impurity metal element in addition to the zirconium, the indium, and the silicon. Oxide sputtering target.
5. The oxide sputtering target according to any one of claims 1 to 4, wherein the specific resistance value is 1.0 × 10 ^{-2 Ω · cm or less.}
6. A method for producing an oxide sputtering target composed of an oxide having a cylindrical shape and containing zirconium, silicon, and indium as metal components.
   A raw material slurry generation step in which zirconium oxide powder, silicon oxide powder and indium oxide powder are mixed and a binder is added to form a slurry.
   A drying step of drying the raw material slurry by a spray-drying method to obtain a sintered raw material powder,
   A molding step of filling the obtained sintered raw material powder into a rubber mold in which a core metal is arranged to obtain a cylindrical molded body by a cold isotropic pressure method.
   A degreasing step of removing the binder from the molded product,
   A method for producing an oxide sputtering target, which comprises a sintering step of sintering a degreased molded product in an oxygen atmosphere to obtain a sintered body.
7. The method for producing an oxide sputtering target according to claim 6, wherein the density variation in the axial direction of the cylindrical molded body is within 3%.
8. The method for producing an oxide sputtering target according to claim 6 or 7, wherein wax is added in the raw material slurry generation step.
9. The method for producing an oxide sputtering target according to any one of claims 6 to 8, wherein the core metal is subjected to a surface smoothing treatment.
10. The method for producing an oxide sputtering target according to any one of claims 6 to 9, wherein the arithmetic mean roughness Ra of the surface of the core metal is 1.6 μm or less.
11. The method for producing an oxide sputtering target according to any one of claims 6 to 10, wherein the Vickers hardness of the core metal is 180 Hv or more.
12. The method for producing an oxide sputtering target according to any one of claims 6 to 11, wherein the pressurizing pressure in the molding step is 100 MPa or more.

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