WO2021251094A1 - Sputtering target, method for producing sputtering target and optical functional film - Google Patents

Abstract

This sputtering target comprises a zinc oxide phase and one or more metal phases that are selected from among Nb, W and Ti, while having a density ratio of 80% or more; and the standard deviation of the respective contents of the one or more metal elements selected from among Nb, W and Ti, said contents being measured at a plurality of sites in the sputtering surface, is 5 mass% or less.

Description

Sputtering target, manufacturing method of sputtering target, and optical functional film

The present invention relates to a sputtering target used for forming an optical functional film that is laminated on, for example, a metal thin film to reduce reflection of light from the metal thin film, a method for manufacturing the sputtering target, and an optical functional film. It is about.
This application claims priority based on Japanese Patent Application No. 2020-099577 filed in Japan on June 8, 2020, the contents of which are incorporated herein by reference.

In recent years, a projection type capacitive touch panel has been adopted as an input means for a mobile terminal device or the like. In this type of touch panel, a sensing electrode is formed for touch position detection. The electrode for sensing is usually formed by patterning, and an X electrode extending in the X direction and a Y electrode extending in the Y direction orthogonal to the X direction are formed on one surface of the transparent substrate. These are provided and arranged in a grid pattern.
Here, when a metal film is used for the electrodes of the touch panel, the pattern of the electrodes is visually recognized from the outside because the metal film has a metallic luster. Therefore, it is conceivable to reduce the visibility of the electrodes by forming a low-reflectance film having a low reflectance of visible light on the metal thin film.

Further, in a flat panel display represented by a liquid crystal display device or a plasma display, a color filter for color display is adopted. In this color filter, a black member called a black matrix is formed for the purpose of improving contrast and color purity and improving visibility.
The above-mentioned low reflectance film can also be used as this black matrix (hereinafter referred to as “BM”).

Further, in the solar cell panel, when sunlight is incident through a glass substrate or the like, a back electrode of the solar cell is formed on the opposite side thereof. As the back surface electrode, a metal film such as molybdenum (Mo) or silver (Ag) is used. When the solar cell panel of such an aspect is viewed from the back surface side, the metal film which is the back surface electrode thereof is visually recognized.
Therefore, it is conceivable to reduce the visibility of the back surface electrode by forming the above-mentioned low reflectance film on the back surface electrode.

Here, for example, Patent Document 1 proposes a sputtering target containing an oxide and an oxynitride as a sputtering target for forming the above-mentioned low reflectance film (optical functional film).

Here, in the sputtering target described in Patent Document 1, sintering is performed at a temperature of 1000 ° C. or higher, but when zinc oxide (ZnO) is contained as an oxide, zinc oxide (ZnO) is contained. However, depending on the contained metal element, zinc oxide is reduced to sublimate Zn, which causes a problem of composition deviation or a decrease in density.

Furthermore, the above-mentioned optical functional film is required to have durability so that the optical characteristics do not change significantly during manufacturing and use. For example, when the heating step is carried out after the film formation, heat resistance is required. Further, when a wiring pattern is formed by etching, alkali resistance is required because alkali is used when developing or peeling the resist film.

Japanese Patent No. 6161095

The present invention has been made in view of the above-mentioned circumstances, and efficiently stabilizes an optical functional film having excellent heat resistance and alkali resistance and capable of sufficiently suppressing reflection of light from a metal thin film or the like. It is an object of the present invention to provide a sputtering target capable of forming a film, a method for manufacturing the sputtering target, and an optical functional film.

In order to solve the above problems, the sputtering target according to one aspect of the present invention contains one or more metal phases selected from Nb, W, Ti and a zinc oxide phase, and has a density ratio of 80. % Or more, and the standard deviation of the content of each of one or two or more kinds of metal elements selected from Nb, W, Ti measured at a plurality of points on the sputtered surface is 5 mass% or less. It is a feature.

According to the sputtering target having this configuration, since it contains one or more kinds of metal phases selected from Nb, W, and Ti and a zinc oxide phase, it has excellent optical properties, heat resistance, and resistance. It is possible to form an optical functional film having excellent alkalinity.
Since the density ratio is 80% or more, it is possible to suppress the occurrence of abnormal discharge during sputtering.
Further, since the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti measured at a plurality of points on the spatter surface is 5 mass% or less, the reflectance is increased. It is possible to form an optical functional film with little variation.

Here, in the sputtering target according to one aspect of the present invention, it is preferable that ^{the average particle area of the pores is 5 μm 2 or less.}
In this case, since the average particle area of the pores ^{is limited to 5 μm 2} or less, it is possible to suppress the occurrence of abnormal discharge due to the pores during sputtering, and it is possible to form an optical functional film more stably. Become.

Further, in the sputtering target according to one aspect of the present invention, one or more kinds of metal M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W and Y. It is preferable that the total content of the metal M containing an oxide is in the range of 0.1 mass% or more and 40 mass% or less, with 100 mass% of all metal elements.
In this case, since the above-mentioned oxide of the metal M is contained in the range of 0.1 mass% or more and 40 mass% or less with the total metal element as 100 mass%, the heat resistance and alkali resistance of the formed optical functional film can be improved. It can be further improved.

Further, in the sputtering target according to one aspect of the present invention, the ratio of the standard deviation of the specific resistance values measured at a plurality of points on the sputtering surface divided by the average value is preferably 100% or less.
In this case, since the variation in the specific resistance value on the sputtered surface is suppressed, the occurrence of abnormal discharge during sputtering can be suppressed, and the optical functional film can be more stably formed.

Further, in the sputtering target according to one aspect of the present invention, the total content of Nb, W, and Ti is preferably 50 mass% or more with respect to the whole including O and C.
In this case, since the total content of Nb, W, and Ti is 50 mass% or more with respect to the whole including O and C, the specific resistance is sufficiently low and the occurrence of abnormal discharge can be further suppressed.
Further, the heat resistance and alkali resistance of the formed optical functional film can be further improved.

Further, in the sputtering target according to one aspect of the present invention, it is preferable that C is further contained in the range of 1 mass% or more and 10 mass% or less with respect to the whole.
In this case, by containing 1 mass% or more of C with respect to the whole, the heat resistance and alkali resistance of the formed optical functional film can be further improved. Further, since the C content is limited to 10 mass% or less with respect to the whole, it is possible to secure the etching property of the formed optical functional film.

The method for producing a sputtering target according to one aspect of the present invention is a method for producing a sputtering target containing one or more metal phases selected from Nb, W, Ti and a zinc oxide phase, and is an average. A metal powder consisting of one or more kinds selected from Nb, W, Ti having a particle size of 5 μm or more and zinc oxide powder having an average particle size of 1 μm or less are used in a solvent having a water concentration of 30 vol% or more. Baking to obtain granulated powder by mixing and drying to obtain granulated powder, and heating and pressurizing the obtained granulated powder at a temperature of 1000 ° C. or lower and a pressure of 145 MPa or higher. It is characterized by having a binding process.

According to the method for producing a sputtering target having this configuration, one or more metal powders selected from Nb, W, and Ti having an average particle size of 5 μm or more and zinc oxide powder having an average particle size of 1 μm or less are used. , Are mixed with a solvent having a water concentration of 30 vol% or more and dried to obtain a granulated powder. Therefore, a metal powder having a large particle size and a zinc oxide powder having a small particle size are provided. It is possible to obtain a granulated powder in which and is uniformly mixed. Therefore, in the subsequent sintering step, the sublimation of zinc oxide and the reduction reaction of zinc oxide can be suppressed, the generation of gas can be suppressed, the density can be improved, and the occurrence of composition deviation can be suppressed.
Further, since the obtained granulated powder is provided with a sintering step of heating and pressurizing the obtained granulated powder at a temperature of 1000 ° C. or lower and a pressure of 145 MPa or higher, the density can be sufficiently improved.

Here, in the method for manufacturing a sputtering target according to one aspect of the present invention, a molding step of pressurizing the granulated powder at room temperature to form the granulated powder may be provided before the sintering step.
In this case, since the molding step of pressurizing and molding the granulated powder at room temperature is provided, a sintered body having a further improved density can be obtained.

Further, in the method for producing a sputtering target according to one aspect of the present invention, in the granulation powder production step, in addition to the metal powder and the zinc oxide powder, the average particle size is within the range of 0.1 μm or more and 12 μm or less. One or more kinds of metal M oxide powders selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y may be mixed.
In this case, it is possible to produce a sputtering target containing an oxide of one or more kinds of metal M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W and Y. can.
Since the average particle size of the oxide powder of the metal M is within the range of 0.1 μm or more and 12 μm or less, the density can be sufficiently improved and the oxide of the metal M is caused at the time of sputtering. The occurrence of abnormal discharge can be suppressed.

Further, in the method for producing a sputtering target according to one aspect of the present invention, it is preferable that the average particle size of the zinc oxide powder is 100 nm or less.
In this case, it is possible to further improve the density.

Further, in the method for producing a sputtering target according to one aspect of the present invention, it is preferable that the average particle size of the metal powder is 10 μm or more.
In this case, it is possible to further improve the density.

The optical functional film according to one aspect of the present invention is an optical functional film containing one or more metals selected from Nb, W, Ti and zinc oxide, and is selected from Nb, W, Ti. It is characterized in that the standard deviation of the content of each of one or more kinds of metal elements is 5 mass% or less.

According to the optical functional film having this configuration, since it contains one or more metals selected from Nb, W, and Ti and zinc oxide, it has excellent optical properties and excellent heat resistance and alkali resistance. ing.
Since the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti is 5 mass% or less, the variation in reflectance becomes small.

Here, in the optical functional film according to one aspect of the present invention, one or more kinds of metals selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, Y. It may contain an oxide of M.
In this case, since it contains an oxide of one or more kinds of metal M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y, it has heat resistance. And it becomes possible to further improve the alkali resistance.

According to one aspect of the present invention, a sputtering target capable of efficiently and stably forming an optical functional film having excellent heat resistance and alkali resistance and capable of sufficiently suppressing reflection of light from a metal thin film or the like. It becomes possible to provide a method for manufacturing a sputtering target and an optical functional film.

It is sectional drawing explanatory drawing of the laminated film provided with the optical functional film which concerns on one Embodiment of this invention. It is a top view of the optical functional film of FIG. It is a schematic explanatory drawing of the sputtering target which is the sputtering target which concerns on one Embodiment of this invention, and has the shape of a flat plate. It is a schematic explanatory drawing of the sputtering target which is the sputtering target which concerns on one Embodiment of this invention, and has a disk shape. It is a top view of the schematic explanatory view of the sputtering target which is the sputtering target which concerns on one Embodiment of this invention and has a cylindrical shape. It is sectional drawing along the axis of the schematic explanatory view of the sputtering target which is the sputtering target which concerns on one Embodiment of this invention and has a cylindrical shape. It is a flow figure which shows the manufacturing method of the sputtering target which concerns on one Embodiment of this invention.

Hereinafter, the sputtering target, the method for manufacturing the sputtering target, and the optical functional film according to the embodiment of the present invention will be described with reference to the attached drawings.

As shown in FIG. 1, the optical functional film 12 according to the present embodiment is formed so as to be laminated on the metal wiring film 11 formed on the surface of the substrate 1.
Here, the metal wiring film 11 is made of aluminum, which is a metal having excellent conductivity, an aluminum alloy, copper, a copper alloy, or the like, and in the present embodiment, it is made of copper. Since the metal wiring film 11 has a metallic luster, it reflects visible light and is visually recognized from the outside.

The optical functional film 12 of the present embodiment is provided to suppress the reflection of visible light in the laminated metal wiring film 11.
The optical functional film 12 of the present embodiment contains one or more metals selected from Nb, W, and Ti and zinc oxide.
The standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti is 5 mass% or less.
Further, the optical functional film 12 of the present embodiment is used to oxidize one or more metals M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y. It may contain objects.
Further, the optical functional film 12 of the present embodiment contains one or more selected from Nb, W, and Ti in a total amount of 50 mass% or more and 80 mass% or less, Zn in an amount of 10 mass% or more and 30 mass% or less, and the balance is oxygen. And unavoidable impurities, and if necessary, one or more metals M selected from Al, Si, Ga, In, Sn, Zr, Mo, Ta, and Y are added in a total of 40 mass% or less, C. May be included within the range of 10 mass% or less.

Here, in the above-mentioned optical functional film 12, as shown in FIG. 2, the content of one or more metal elements selected from Nb, W, and Ti is measured at five points on the film surface. The standard deviation of the contents of these metal elements is calculated.
Specifically, when the film surface of the optical functional film 12 is rectangular as shown in FIG. 2, the measurement points are one point of intersection where diagonal lines connecting the opposite corners of the film surface intersect, and diagonal lines from the corners on each diagonal line. There are 5 points at 4 points within 10% of the total length of the. When the film surface of the optical functional film 12 is circular, the measurement point is within 10% of the total length of the diagonal line from the outer peripheral portion on two straight lines passing through the center of the film surface and the center of the film surface and orthogonal to each other. There are 5 points of 4 points at the position.
The respective contents of Nb, W, and Ti measured to obtain the standard deviation also include Nb, W, and Ti contained in the oxide of the metal M.
The standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti in the optical functional film 12 is preferably 3 mass% or less, and preferably 1 mass% or less. More preferred.

Then, the above-mentioned optical functional film 12 is formed into a film using the sputtering target of the present embodiment.
The sputtering target according to the present embodiment will be described below.

The sputtering target of the present embodiment includes one or more metal phases selected from Nb, W, Ti and a zinc oxide phase.
Further, the sputtering target of the present embodiment has a density ratio of 80% or more.
Further, in the sputtering target of the present embodiment, the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti measured at a plurality of points on the sputtering surface is 5 mass% or less. It is said that.

Here, in the sputtering target of the present embodiment, the total content of Nb, W, and Ti is preferably 50 mass% or more.
Further, in the sputtering target of the present embodiment, one or more metal M oxides selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y are used. The total content of the metal M may be in the range of 0.1 mass% or more and 40 mass% or less, where 100 mass% is the total metal element.
The total content of Nb, W, and Ti described above also includes Nb, W, and Ti contained in the oxide of the metal M. The total content of the metal M is the total content of the metal M in the oxide of the metal M, and does not include the amounts of Nb, W, and Ti in the metal phase.
Further, in the sputtering target of the present embodiment, C may be contained in the range of 1 mass% or more and 10 mass% or less.
Further, in the sputtering target of the present embodiment, one or more selected from Nb, W, and Ti are contained in a total amount of 50 mass% or more and 80 mass% or less, Zn is contained in an amount of 10 mass% or more and 30 mass% or less, and the balance is oxygen and It is preferably composed of unavoidable impurities, and if necessary, one or more metals M selected from Al, Si, Ga, In, Sn, Zr, Mo, Ta, and Y are added in a total of 40 mass% or less, C. It may be contained within the range of 10 mass% or less.

Further, in the sputtering target of the present embodiment, it is preferable that ^{the average particle area of the pores is 5 μm 2 or less.}
Further, in the sputtering target of the present embodiment, the ratio of the standard deviation of the specific resistance values measured at a plurality of points on the sputtering surface divided by the average value is preferably 100% or less.

Below, in the sputtering target of the present embodiment, the phase composition, the density ratio, the standard deviation of the content of each metal element in the sputtered surface, the average particle area of pores, the composition, and the variation in the specific resistance value in the sputtered surface are described. , The reasons specified above are shown.

(Phase composition)
The sputtering target of the present embodiment contains one or more metal phases selected from Nb, W, and Ti, and a zinc oxide phase.
This makes it possible to form the optical functional film 12 of the present embodiment by sputtering. The optical functional film 12 is excellent in optical characteristics, heat resistance and alkali resistance.
The area ratio (percentage) of the metal phase / (metal phase + zinc oxide phase) is preferably 10 to 95%, more preferably 20 to 80%, still more preferably 30 to 70%.
The area of each phase is measured by the following method. The composition image (COMPO image) of the sample collected from the sputtering target is photographed using an electron probe microanalyzer (EPMA) device, and element mapping is performed. The element mapping image of zinc is binarized by Brightness using the image processing software ImageJ. Calculate the area of the zinc-containing region. The area of the zinc-containing region is defined as the area of the zinc oxide phase. Next, in the element mapping image of Nb, W, Ti, O, a binarized image of the content region of Nb, W, Ti, O is obtained. The Nb, W, and Ti-containing regions are made black, the O-containing regions are made white, and the surroundings are transparently image-processed. By superimposing the binarized image of the O-containing region on the binarized image of the Nb, W, Ti-containing region, a region containing Nb, W, Ti as a metal component is obtained. In the obtained image, the area of the region containing Nb, W, and Ti as metal components is calculated. That is, the area of the region containing Nb, W, and Ti that does not contain O is defined as the area of the metal phase.

(Density ratio)
In the sputtering target of this embodiment, the density ratio is 80% or more. As a result, the occurrence of abnormal discharge during sputtering can be suppressed, and the optical functional film 12 of the present embodiment can be stably formed.
The density ratio is preferably 85% or more, and more preferably 90% or more. The upper limit of the density ratio is preferably 100% or less.

(Standard deviation of the content of each metal element in the sputtered surface)
In the sputtering target of the present embodiment, the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti measured at a plurality of points on the sputtering surface is 5 mass% or less. Has been done. When at least one metal element among Nb, W, and Ti is contained, the standard deviation of the contained metal element is an index showing the magnitude of variation in the content of the metal element, and is set to 5 mass% or less. There is.
The respective contents of Nb, W, and Ti measured to obtain the standard deviation also include Nb, W, and Ti contained in the oxide of the metal M.
This makes it possible to form an optical functional film 12 having little variation in reflectance. As the variation in the reflectance of the optical functional film 12, the standard deviation of the reflectance measured at a plurality of points is preferably 3.0% or less, and preferably 2.5% or less.
The standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti on the sputtered surface is preferably 4 mass% or less, and more preferably 3 mass% or less. ..

Here, in the present embodiment, the standard deviation of the content of each metal element in the sputtered surface is, for example, the angle at which the sputtered surfaces face each other when the sputtered surface of the sputtering target is rectangular as shown in FIG. At the intersection (1) where the diagonal lines connecting the parts intersect, and at the five points (2), (3), (4), and (5) located within 10% of the total length of the diagonal line from the corners on each diagonal line. , It is preferable to measure the content of each metal element and calculate the standard deviation.

Further, as shown in FIG. 4, when the sputtering surface of the sputtering target is circular, the center of the sputtering surface (1) and the outer peripheral portions on two straight lines passing through the center of the sputtering surface and orthogonal to each other. The content of each metal element can be measured and the standard deviation can be calculated at the five points (2), (3), (4), and (5) located within 10% of the total length of the diagonal line. preferable.

Further, when the sputtering surface of the sputtering target forms a cylindrical surface as shown in FIGS. 5A and 5B, the sputtered surfaces are spaced 90 ° in the circumferential direction at both ends A and B in the axis O direction and the central portion C. It is preferable to measure the content of each metal element at a total of 12 points (1), (2), (3), and (4) and calculate the standard deviation.

(Average particle area of pores)
In the sputtering target of the present embodiment, when the average particle area of the pores is 5 μm ² or less, the generation of abnormal discharge due to the pores during sputtering can be suppressed, and the optical functional film 12 is formed more stably. It becomes possible to make a film.
The average particle area of the pores ^{is more preferably 4 μm 2} or less, and ^{further preferably 3 μm 2} or less.

(composition)
In the sputtering target of the present embodiment, when the total content of Nb, W, and Ti is 50 mass% or more, the specific resistance of the sputtering target becomes sufficiently low, and the occurrence of abnormal discharge during sputtering is suppressed. Therefore, the optical functional film 12 can be stably formed. Further, the heat resistance and alkali resistance of the formed optical functional film 12 can be further improved.
The lower limit of the total content of Nb, W, and Ti is more preferably 55 mass% or more, and further preferably 60 mass% or more. Further, the upper limit of the total content of Nb, W, and Ti is preferably 90 mass% or less, and more preferably 80 mass% or less.

Further, in the sputtering target of the present embodiment, one or more kinds of metal M oxides selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y are used. When the total content of the metal M is within the range of 0.1 mass% or more and 40 mass% or less with 100 mass% of all metal elements, the heat resistance and resistance of the formed optical functional film 12 It is possible to further improve the alkalinity and suppress the occurrence of abnormal discharge due to the oxide of the metal M at the time of sputtering.
When one or more kinds of metal M oxides selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y are contained, all metal elements are used. The lower limit of the total content of the metal M as 100 mass% is more preferably 1 mass% or more, and further preferably 5 mass% or more. Further, the upper limit of the total content of the metal M is more preferably 35 mass% or less, and further preferably 30 mass% or less.

Further, when the sputtering target of the present embodiment contains C in the range of 1 mass% or more and 10 mass% or less, the heat resistance and alkali resistance of the film-formed optical functional film 12 can be further improved. ..
In addition, in order to obtain the above-mentioned action and effect by containing C, the lower limit of the content of C is more preferably 2 mass% or more, and further preferably 3 mass% or more. Further, in order to maintain low reflectance during metal lamination, the upper limit of the C content is preferably 7 mass% or less, and more preferably 5 mass% or less.

(Specific resistance value)
Further, in the sputtering target of the present embodiment, when the ratio obtained by dividing the standard deviation of the specific resistance values measured at a plurality of points on the sputtering surface by the average value is 100% or less, an abnormal discharge occurs during sputtering. Can be suppressed, and a more stable optical functional film can be formed.
The ratio of the standard deviation of the specific resistance values measured at a plurality of points on the spatter surface divided by the average value is more preferably 100% or less, and more preferably 50% or less.
The points where the specific resistance value is measured are the same as the points where the content of the metal element in FIGS. 3, 4, 5A and 5B is measured.

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

In the present embodiment, as shown in FIG. 6, a metal powder composed of one or more kinds selected from Nb, W, and Ti and zinc oxide powder are mixed using a solvent to obtain a granulated powder. It includes a grain powder producing step S01, a sintering step S02 in which the obtained granulated powder is pressurized and heated to be sintered, and a machining step S03 in which the obtained sintered body is machined.

(Granulation powder production step S01)
In this granulation powder preparation step S01, one or more metal powders selected from Nb, W, Ti having an average particle diameter of 5 μm or more and zinc oxide powder having an average particle diameter of 1 μm or less are used. prepare.
Then, these metal powders and zinc oxide powders are mixed using a solvent having a water concentration of 30 vol% or more and dried to obtain granulated powder. Examples of the solvent include pure water, a mixed solution of pure water and ethanol, and the like.

Here, the average particle size of one or more metal powders selected from Nb, W, and Ti is 5 μm or more, and the average particle size of zinc oxide powder is 1 μm or less. Occasionally, it is possible to suppress the generation of gas due to the sublimation of zinc oxide and metallic zinc, and it is possible to improve the density of the sintered body.
Further, by mixing the metal powder and the zinc oxide powder with a solvent having a water concentration of 30 vol% or more, the metal powder and the zinc oxide after drying are produced by the aggregation effect of the powder due to the surface tension of the solvent during slurry drying. Separation from powder can be suppressed, and variation in composition can be suppressed.

The lower limit of the average particle size of one or more metal powders selected from Nb, W, and Ti is preferably 7 μm or more, and more preferably 10 μm or more. The upper limit of the average particle size of the metal powder is preferably 20 μm or less, and more preferably 18 μm or less.
Further, the upper limit of the average particle size of the zinc oxide powder is preferably 500 nm or less, more preferably 100 nm or less. Further, the lower limit of the average particle size of the zinc oxide powder is preferably 30 nm or more, more preferably 50 nm or more.
Further, the concentration of water in the solvent is preferably 50 vol% or more, more preferably 80 vol% or more.

Here, when the sputtering target contains an oxide of one or more kinds of metal M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y. In this granulated powder manufacturing step S01, in addition to the above-mentioned metal powder and zinc oxide powder, Al, Si, Ga, In, Sn, Ti, whose average particle diameter is within the range of 0.1 μm or more and 12 μm or less. Oxide powder of one or more kinds of metal M selected from Nb, Zr, Mo, Ta, W and Y is mixed with a solvent having a water concentration of 30 vol% or more to prepare a granulated powder. Is preferable.
By setting the average particle size of the oxide powder of the metal M to 0.1 μm or more, it is possible to improve the density of the sintered body. On the other hand, by setting the average particle size of the oxide powder of the metal M to 12 μm or less, it is possible to suppress the occurrence of abnormal discharge due to the oxide of the metal M during sputtering.
The lower limit of the average particle size of the oxide powder of the metal M is preferably 0.3 μm or more, and more preferably 0.5 μm or more. Further, the upper limit of the average particle size of the oxide powder of the metal M is preferably 10 μm or less, and more preferably 7 μm or less.
When the sputtering target contains C, it is preferable to mix the C powder in addition to the above-mentioned metal powder, zinc oxide powder, and metal M oxide powder in the granulation powder production step S01. The average particle size of the C powder is preferably 2 to 10 μm.
The mixing ratio of the metal powder, the zinc oxide powder, the oxide powder of the metal M, and the C powder is adjusted so as to obtain the composition of the target sputtering target.
The amount of the solvent added is preferably 1 to 10 times or less with respect to the amount of the raw material powder (metal powder, zinc oxide powder, metal M oxide powder, and C powder).

(Sintering step S02)
Next, the above-mentioned granulated powder is sintered by heating while pressurizing to obtain a sintered body.
The sintering temperature in the sintering step S02 is 1000 ° C. or lower, and the pressurizing pressure is 145 MPa or higher.
Here, by setting the sintering temperature to 1000 ° C. or lower, sublimation of zinc oxide and metallic zinc can be suppressed. Further, by setting the pressurizing pressure to 145 MPa or more, it is possible to improve the density.
The upper limit of the sintering temperature is preferably 950 ° C or lower, more preferably 900 ° C or lower. On the other hand, the lower limit of the sintering temperature is preferably 600 ° C. or higher, more preferably 700 ° C. or higher.
Further, the lower limit of the pressurizing pressure is preferably 150 MPa or more, and more preferably 155 MPa or more. On the other hand, the upper limit of the pressurizing pressure is preferably 200 MPa or less, more preferably 170 MPa or less.

(Machining process S03)
Next, the obtained sintered body is machined to have a predetermined size. As a result, the sputtering target according to the present embodiment is manufactured.

According to the sputtering target of the present embodiment having the above configuration, since it contains one or more kinds of metal phases selected from Nb, W, Ti and a zinc oxide phase, it is optical. It is possible to form an optical functional film 12 having excellent characteristics and excellent heat resistance and alkali resistance.
Since the density ratio is 80% or more, it is possible to suppress the occurrence of abnormal discharge during sputtering.
Further, since the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti measured at a plurality of points on the spatter surface is 5 mass% or less, the reflectance is increased. It is possible to form an optical functional film 12 with little variation.

In the sputtering target of the present embodiment, when the average particle area of the pores is 5 μm ² or less, the generation of abnormal discharge due to the pores during sputtering can be suppressed, and the optical functional film 12 is formed more stably. It becomes possible to make a film.

Further, in the sputtering target of the present embodiment, one or more kinds of metal M oxides selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y are used. When the total content of the metal M is within the range of 0.1 mass% or more and 40 mass% or less with 100 mass% of all metal elements, the heat resistance and alkali resistance of the formed optical functional film 12 Can be further improved.

Further, in the sputtering target of the present embodiment, when the ratio obtained by dividing the standard deviation of the specific resistance values measured at a plurality of points on the sputtering surface by the average value is 100% or less, an abnormal discharge occurs during sputtering. Can be suppressed, and a more stable optical functional film can be formed.

Further, in the sputtering target of the present embodiment, when the total content of Nb, W, and Ti is 50 mass% or more, the specific resistance is sufficiently low, and the occurrence of abnormal discharge during sputtering can be further suppressed. Further, the heat resistance and alkali resistance of the formed optical functional film 12 can be further improved.

Further, when the sputtering target of the present embodiment contains C in the range of 1 mass% or more and 10 mass% or less, the heat resistance and alkali resistance of the formed optical functional film 12 can be further improved, and the heat resistance and alkali resistance of the film-formed optical functional film 12 can be further improved. It is possible to secure the etching property of the formed optical functional film 12.

According to the method for producing a sputtering target according to the present embodiment, one or more metal powders selected from Nb, W, and Ti having an average particle size of 5 μm or more and zinc oxide having an average particle size of 1 μm or less are used. Since the granulated powder manufacturing step S01 is provided in which the powder and the powder are mixed with a solvent having a water concentration of 30 vol% or more and the solvent is dried to obtain a granulated powder, the metal powder having a large particle size and the particle size are provided. It is possible to obtain a granulated powder in which a small amount of zinc oxide powder is uniformly mixed. Therefore, in the subsequent sintering step, the sublimation of zinc oxide and the reduction reaction of zinc oxide can be suppressed, the generation of gas can be suppressed, the density can be improved, and the occurrence of composition deviation can be suppressed.
Further, since the sintering step S02 for heating and pressurizing the obtained granulated powder at a temperature of 1000 ° C. or lower and a pressure of 145 MPa or higher is provided, the density can be sufficiently improved.

In the method for producing a sputtering target according to the present embodiment, in the granulation powder preparation step S01, in addition to the metal powder and zinc oxide powder, Al, Si, whose average particle size is within the range of 0.1 μm or more and 12 μm or less. When one or more metal M oxide powders selected from Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y are mixed, Al, Si, Ga, In, A sputtering target containing an oxide of one or more kinds of metal M selected from Sn, Ti, Nb, Zr, Mo, Ta, W, and Y can be produced. Further, since the average particle size of the oxide powder of the metal M is within the range of 0.1 μm or more and 12 μm or less, the density can be sufficiently improved and the oxide of the metal M is caused at the time of sputtering. The occurrence of abnormal discharge can be suppressed.

In the method for producing a sputtering target according to the present embodiment, the average particle size of zinc oxide powder is 100 nm or less, or the average particle size of one or more metal powders selected from Nb, W, and Ti is 10 μm or more. If this is the case, it is possible to further improve the density.

According to the optical functional film 12 of the present embodiment, since it contains one or more metals selected from Nb, W, and Ti and zinc oxide, it has excellent optical properties, heat resistance, and resistance. Has excellent alkalinity.
Since the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti is 5 mass% or less, the variation in reflectance is reduced.

In the optical functional film 12 of the present embodiment, an oxide of one or more kinds of metal M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W, and Y is used. If it is contained, heat resistance and alkali resistance can be further improved.

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 requirements of the invention.
In the present embodiment, it has been described that the sintering step is carried out after the granulation powder preparation step, but the present invention is not limited to this, and the granulation is performed between the granulation powder preparation step and the sintering step. A molding step of pressurizing the powder at room temperature to form the powder may be carried out, and the obtained molded body may be sintered. The pressurizing pressure in the molding step is preferably 100 MPa or more and 175 MPa or less.

Further, in the present embodiment, as shown in FIG. 1, as a structure in which the optical functional film 12 according to the present embodiment is formed so as to be laminated on the metal wiring film 11 formed on the surface of the substrate 1. As described above, the present invention is not limited to this, and the optical functional film 12 may be formed on the surface of the substrate 1 and the metal wiring film 11 may be laminated on the optical functional film 12. In this case, the reflection from the substrate 1 can be reduced at the same time.

The results of the evaluation test for evaluating the sputtering target according to the present invention, the method for manufacturing the sputtering target, and the action and effect of the optical functional film will be described below.

The metal powders, zinc oxide powders, various metal oxide powders, and C powders shown in Tables 5 to 8 were weighed to a total of 1 kg at the ratios shown in Tables 1 to 4. 1 kg of the weighed raw material powder, 3 kg of zirconia balls having a diameter of 5 mm, and 1 L of a solvent having a water concentration shown in Tables 5 to 8 were placed in a pot having a capacity of 10 L and mixed for 16 hours with a ball mill device. The mixed powder was then dried and sieved through a 250 μm sieve to give granulated powder.
The solvent is a mixed solution of pure water and ethanol, and in the water concentration column of Tables 5 to 8, the water concentration is 100% when the solvent 1 L is only pure water, and the mixed solution of pure water and ethanol is used. The value of water concentration is described. The dry mixing is described as "dry".

The obtained granulated powder was filled in a rubber mold having a diameter of 250 mm. Then, CIP (Cold Isostatic Pressing) was performed at a pressure of 150 MPa to obtain a molded product.
The obtained molded product was placed in a steel can having a diameter of 220 mm and evacuated at 300 ° C. Next, the molded product was sealed in a can and subjected to HIP (Hot Isostatic Pressing) under the conditions of holding at the temperatures and pressures shown in Tables 5 to 8 for 3 hours to obtain a sintered body. ..
The obtained sintered body was machined to φ125 mm × thickness t5 mm and bonded to a backing plate made of Cu with In solder to obtain a sputtering target.

For the average particle size of the raw material powder, 100 mL of an aqueous solution having a sodium hexametaphosphate concentration of 0.2% was prepared, 10 mg of the raw material powder was added to this aqueous solution, and a laser diffraction scattering method (measuring device: Microtrac MT3000 manufactured by Nikkiso Co., Ltd.) was added. The particle size distribution was measured using. The arithmetic average diameter (volume average diameter) was calculated from the obtained particle size distribution, and is shown in Tables 5 to 8 as the average particle size.

As described above, the obtained sputtering target and the optical functional film formed by using this sputtering target were evaluated for the following items.

(Metal phase)
Samples were taken from the resulting sputtering target and analyzed by XRD. When the peaks belonging to Nb phase ID: 01-073-3816, W phase ID: 01-004-0806, and Ti phase: 00-044-1294 were obtained, it was determined that each metal phase was present. Further, when the peak attributable to ZnO phase ID: 00-036-1451 was obtained, it was determined that there was a ZnO phase. As a result, in all of Examples 1 to 61 of the present invention, one or more metal phases of Nb, W, and Ti (one or more of Nb phase, W phase, and Ti phase) and ZnO phase were confirmed.
The obtained membrane was analyzed by XPS. From the peaks of Nb: 3d orbital, W: 4f orbital, Ti: 2p orbital, and Zn: 2p orbital, in Examples 1 to 61 of the present invention, all of them are changed to one or more of Nb, W, and Ti metal phase and ZnO phase. The derived peak was confirmed.

(Composition of sputtering target)
A sample was taken from the obtained sputtering target, dissolved with an acid or an alkali, and then the metal element was quantified by ICP-AES. As for C, C was quantified by a gas analyzer manufactured by LECO.
The content of each element with respect to the whole including C and O is shown in the column of "Sputtering target composition" in Tables 9 to 12.
Further, when the oxide of the metal M is contained, the content of the metal M is shown in the column of "Ratio of the metal element M to the total metal elements" in Tables 9 to 12, with the total metal element as 100 mass%.
In the example 15 of the present invention, the metal Nb and the Nb oxide are contained, in the example 37 of the present invention, the metal W and the W oxide are contained, and in the example 50 of the present invention, the metal Ti and the Ti oxide are contained. For these, the amount of the metal component of the metal oxide will also be added to the content of the metal element in the column of "blasting target composition" (indicated by "*" in Tables 9, 10 and 11). Therefore, the amount of the metal component of the metal oxide is counted in both the column of "sputtering target composition" and the column of "ratio of metal element M to all metal elements". That is, the amount of Nb, W, Ti in the column of "sputtering target composition" includes the amount of Nb, W, Ti in the metal oxide. As for the metal component of the metal oxide, the quantitative values of the metal components of Nb, W, and Ti derived from the oxide were adopted from the semi-quantitative analysis result of the XPS apparatus. That is, the amount of Nb, W, Ti in the column of "ratio of metal element M in all metal elements" is the amount of Nb, W, Ti in the metal oxide.

(Density ratio of sputtering target)
The volume was calculated from the dimensions of the obtained target, and the density was calculated by dividing the weight by the volume. Furthermore, the density ratio (%) was calculated by dividing the measured density by the ideal calculated density obtained from the charged composition. The evaluation results are shown in Tables 13-16.

(Standard deviation of metal elements)
Target pieces were collected from 5 points on the sputtered surface of the obtained sputtering target, metal elements were quantified by the above method, and the standard deviation σ of the results of the 5 points is shown in the table. Regarding the sample location, when the center coordinates of the surface of φ125 mm are (x mm, y mm) = (0, 0), (x, y) = (0, 0), (-60, 0), (+60) , 0), (0, -60), (0, +60). The evaluation results are shown in Tables 13-16.

(Specific resistance value)
The sputtered surface of the obtained sputtering target was measured in an atmosphere of 25 ± 5 ° C. (20 to 30 ° C.) using a Mitsubishi Gas Chemical Company's four-probe resistance measuring instrument Lorester.
Then, the resistivity values were measured at the five positions shown in the column of standard deviation of the metal element, and the ratio of the standard deviation divided by the average value is shown in the table. The evaluation results are shown in Tables 13-16.
In the table, the specific resistance value “a × 10 ^−b Ω · cm” is described as “aE−b”.

(Average particle area of pores)
The sample collected from the obtained sputtering target is embedded with resin, then polished, and a composition image of 60 μm in length and 76 μm in width at a magnification of 1500 times using an electron probe microanalyzer (EPMA) device (manufactured by JEOL Ltd.). (COMPO image) was photographed. The obtained image was binarized by Brightness using the image processing software ImageJ. At this time, the threshold value of Brightness was set to 120. That is, only the region of the pores with low brightness was detected. Binarization was performed, and then the average particle area of the obtained image was determined using the Particle measurement function. The obtained values are shown in Tables 13 to 16 as the average particle area of the pores.

(Abnormal discharge measurement)
The above-mentioned sputtering target was sputtered with Ar50sccm, 0.4Pa, DC615W (RPG-50 manufactured by mks), and the number of abnormal discharges when sputtered for 1 hour was measured using the count function of the power supply. The evaluation results are shown in Tables 13-16.
In the sputtering targets of Comparative Examples 1 to 3, abnormal discharges occurred frequently, and holes were opened on the sputtering surface of the target due to the abnormal discharges. Therefore, it was judged that the film formation evaluation could not be continued.

(Composition of optical functional film)
Using the sputtering target of the above-mentioned example of the present invention, a film having a thickness of 50 nm was formed on a Si substrate under the conditions of Ar50sccm, 0.4Pa, and DC615W. A substrate size of φ5 inch was used, and the substrate after film formation was cut into a size of about 20 mm × 20 mm centered on the positions directly above the coordinates of the five locations evaluated for the composition variation of the target, and each was cut out. A total of 5 samples were taken, one for each.
Nb, W and Ti were quantified in the obtained film by quantitative analysis of EPMA, and the standard deviation σ of the results of 5 sheets is shown in Tables 17 to 20.

(Reflectance)
Using a 4N copper target having a diameter of 125 mm and a thickness of t5 mm, a total of five substrates were placed, one each directly above the coordinates at the five locations evaluated in the evaluation of the composition variation of the target. The substrate was a glass substrate having a size of 20 mm × 20 mm (EAGLE XG manufactured by Corning Inc.). A Cu film having a thickness of 200 nm was formed on a glass substrate under the conditions of Ar50sccm, 0.4Pa, and DC615W.
After that, the copper target was replaced with the target of the above-mentioned example of the present invention, and the position of the glass substrate was kept as it was, and under the conditions of Ar50sccm, 0.4Pa, DC615W, optics were applied on the Cu film by the film thickness shown in Tables 17 to 20. A functional film was formed. The reflectance in the visible light region was measured using a spectrophotometer (U-4100 manufactured by Hitachi High-Technologies Corporation) for the substrate film at the obtained coordinates (x, y) = (0, 0). .. The average value of the reflectance from 380 nm to 780 nm is shown in Tables 17 to 20.
As an evaluation of the variation in reflectance, the above-mentioned reflectance was measured for a total of 5 sheets, and the standard deviation σ as a result of the reflectance of 5 sheets is shown in the table. The standard deviation is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less.

(Heat-resistant)
The sample whose reflectance was measured was heated to 400 ° C. at a rate of 10 ° C./sec in a nitrogen atmosphere using a lamp heating furnace and maintained for 10 minutes. Then, after cooling to room temperature, it was taken out, and the reflectance was measured in the same manner. The difference in reflectance before and after the treatment is shown in Tables 17 to 20. This difference is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less.

(Alkaline resistance)
The sample whose reflectance was measured was immersed in a commercially available TMAH (Tetramethylammonium hydroxide) solution (2.38 wt%) at room temperature for 10 min, then rinsed with pure water and dried by air blow. After that, the reflectance was measured in the same manner. The difference in reflectance before and after the treatment is shown in Tables 17 to 20. This difference is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less.

(Etching property)
When the metal was Nb, the obtained 50 nm film was immersed in a fluorine aqueous solution heated to 40 ° C. Metals Ti, in the case of W was immersed in a commercially available _H 2 _{O 2} etchant heating the film obtained 50nm to 40 ° C. (manufactured by Kanto Chemical Co., Inc. GHP-3). In Examples 1 to 61 of the present invention, it was confirmed that all the films could be etched.

In Comparative Example 1, the average particle size of the metal Nb powder was 1.1 μm, and the density ratio of the sputtering target was 70.5%. Therefore, the number of abnormal discharges increased to 234 times / hour, and the optical functional film could not be stably formed.

In Comparative Example 2, the average particle size of the zinc oxide powder was 1300 nm, and the density ratio of the sputtering target was 76.4%. Therefore, the number of abnormal discharges increased to 175 times / hour, and the optical functional film could not be stably formed.

In Comparative Example 3, the sintering temperature was 1100 ° C., and the density ratio of the sputtering target was 78.3%. Therefore, the number of abnormal discharges increased to 142 times / hour, and the optical functional film could not be stably formed.

In Comparative Example 4, since the metal Nb powder and the zinc oxide powder were mixed in a dry manner, the standard deviation of the Nb content on the sputtered surface was as large as 5.2 mass%. Therefore, in the formed optical functional film, the standard deviation of the Nb content is large, and the variation in reflectance (standard deviation) is also large.

In Comparative Example 5, the pressurizing pressure at the time of sintering was 130 MPa, and the density ratio of the sputtering target was 77.7%. Therefore, the number of abnormal discharges increased to 185 times / hour, and the optical functional film could not be stably formed.

On the other hand, in Examples 1 to 61 of the present invention, the density ratio is 80% or more, and the standard deviation of the content of the metal element on the sputter surface is 5 mass% or less. The standard deviation of the content of metal elements was small, and the variation in reflectance (standard deviation) was also kept small. In addition, the occurrence of abnormal discharge was suppressed, and the optical functional film could be stably formed.

Further, it was confirmed that the heat resistance of the optical functional film was further improved in Examples 6 to 8, 16, 24 to 26, 37, 42 to 44, 46, 58 to which C was added.
Further, it was confirmed that the alkali resistance of the optical functional film was further improved in Examples 9 to 20, 27 to 38, 45 to 56, 58 to 61 of the present invention to which the oxide of the metal M was added.

From the above, according to the example of the present invention, it is possible to efficiently and stably form an optical functional film which is excellent in heat resistance and alkali resistance and can sufficiently suppress the reflection of light from a metal thin film or the like. It was confirmed that a sputtering target, a method for manufacturing this sputtering target, and an optical functional film can be provided.

The sputtering target of the present embodiment is suitably applied to a step of forming a low reflectance film provided on an electrode (metal film) for sensing in a projected capacitive touch panel and a black matrix in a flat panel display. ..

12 Optical functional film

Claims (13)

1. It contains one or more metal phases selected from Nb, W, Ti and a zinc oxide phase.
   The density ratio is 80% or more,
   A sputtering target characterized in that the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti measured at a plurality of points on the sputtering surface is 5 mass% or less. ..
2. The sputtering target according to claim 1, wherein the average particle area of the pores is 5 μm ^{2 or less.}
3. It contains an oxide of one or more kinds of metal M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W and Y, and the total content of the metal M is: The sputtering target according to claim 1 or 2, wherein the total metal element is 100 mass% and the range is 0.1 mass% or more and 40 mass% or less.
4. The sputtering target according to any one of claims 1 to 3, wherein the ratio obtained by dividing the standard deviation of the specific resistance values measured at a plurality of points on the sputtering surface by the average value is 100% or less. ..
5. The sputtering target according to any one of claims 1 to 4, wherein the total content of Nb, W, and Ti is 50 mass% or more with respect to the whole including O and C.
6. The sputtering target according to any one of claims 1 to 5, further comprising C in a range of 1 mass% or more and 10 mass% or less with respect to the whole.
7. A method for producing a sputtering target, which comprises one or more metal phases selected from Nb, W, and Ti, and a zinc oxide phase.
   A metal powder consisting of one or more kinds selected from Nb, W, Ti having an average particle diameter of 5 μm or more, and zinc oxide powder having an average particle diameter of 1 μm or less, and a solvent having a water concentration of 30 vol% or more. Granulation powder preparation process to obtain granulation powder by mixing and drying using
   A sintering step in which the obtained granulated powder is sintered by heating and pressurizing at a temperature of 1000 ° C. or lower and a pressure of 145 MPa or higher.
   A method of manufacturing a sputtering target, which comprises.
8. The method for manufacturing a sputtering target according to claim 7, further comprising a molding step of pressurizing and molding the granulated powder at room temperature before the sintering step.
9. In the granulation powder production step, in addition to the metal powder and the zinc oxide powder, Al, Si, Ga, In, Sn, Ti, Nb, whose average particle size is within the range of 0.1 μm or more and 12 μm or less. The method for producing a sputtering target according to claim 7 or 8, wherein the oxide powder of one or more kinds of metal M selected from Zr, Mo, Ta, W, and Y is mixed.
10. The method for producing a sputtering target according to any one of claims 7 to 9, wherein the zinc oxide powder has an average particle size of 100 nm or less.
11. The method for manufacturing a sputtering target according to any one of claims 7 to 10, wherein the average particle size of the metal powder is 10 μm or more.
12. An optical functional film containing zinc oxide and one or more metals selected from Nb, W, and Ti.
    An optical functional film characterized in that the standard deviation of the content of each of one or more metal elements selected from Nb, W, and Ti is 5 mass% or less.
13. 12. Claim 12 comprising an oxide of one or more kinds of metal M selected from Al, Si, Ga, In, Sn, Ti, Nb, Zr, Mo, Ta, W and Y. Optical functional film.

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