Sputtering target and method for producing same

Abstract

The sputtering target according to the present invention has a sputtering target material which includes a sintered body of a metal oxide and has an average delamination area ratio of 6.5% or less, wherein the arithmetic average roughness Ra of the sputtering surface is 0.20 μm or more. The sputtering target production method according to the present invention involves: a step for grinding an oxide sintered body and cleaning same with ultrasonic waves; a step for joining the ground and cleaned oxide sintered body and a base material; and a step for subjecting, to dry-ice blasting, the oxide sintered body joined to the base material.

Description

Sputtering target and manufacturing method thereof

[0001] The present invention relates to a sputtering target and a method for manufacturing the same.

[0002] Sputtering is a type of thin film formation technology. Specifically, in sputtering, an inert gas such as Ar is introduced into a vacuum chamber, and a negative voltage is applied to a target member to generate a glow discharge. During this process, the inert gas is converted into plasma by the glow discharge, and ionized into gas ions (e.g., Ar). ＋ When these gas ions collide with the surface of the target member (sputtering surface) at high speed, particles of the film-forming material that makes up the target member are ejected, and the ejected particles adhere to and deposit on the surface of the substrate on which the thin film is to be formed, forming a dense and strong thin film on the surface of the substrate.

[0003] This thin film formation technology using sputtering makes it possible to form films from materials that are difficult to form films from using vacuum deposition methods, such as high-melting-point metals, alloys, and ceramics. It is particularly used to form thin films for display devices such as liquid crystal displays, touch panels, and EL displays.

[0004] One thing to keep in mind when forming thin films by sputtering is the possibility of arc discharge. Arc discharge, also known as abnormal discharge, causes localized thermal expansion, causing the area to bounce off. When this debris lands on the film, it deposits as particles. One of the causes of abnormal discharge is said to be protrusions on the surface of the sputtering target (sputtering surface). Therefore, methods have been developed to smooth the sputtering surface.

[0005] For example, Patent Document 1 discloses an invention in which a sputtering target manufactured through a surface grinding process is subjected to surface treatment by ejecting dry ice particles together with a gas medium, resulting in a surface roughness Ra of 0.8 μm to 10 μm.

[0006] Japanese Patent Application Laid-Open No. 2005-2364

[0007] However, while the sputtering target subjected to the surface treatment disclosed in Patent Document 1 can reduce particles, the surface roughness Ra of the non-erosion region (non-sputtered region) of the sputtering target is also reduced, making the sputtering products accumulated in the non-erosion region more likely to peel off, which can lead to the generation of nodules and particles. Furthermore, in order to make the surface roughness Ra of the non-erosion region of the sputtering target higher than the surface roughness Ra of the erosion region (sputtered region), it is possible to polish the target by changing the grit size in parts, but this poses problems in mass production. Furthermore, since there is variation in the erosion region and non-erosion region of the sputtering target, it is difficult to obtain consistent results.

[0008] In view of the above problems, the present invention provides a sputtering target that ensures a high surface roughness Ra while suppressing the amount of peeling, and a method for manufacturing the same.

[0009] The sputtering target of the present invention, which has been made to solve the above problems, is characterized by having a sputtering target material made of a sintered body of a metal oxide, in which the average peeling area ratio is 6.5% or less and the arithmetic mean roughness Ra of the sputtering surface is 0.20 μm or more. With this configuration, the sputtering target of the present invention can suppress the amount of peeling while ensuring a high surface roughness Ra.

[0010] The sputtering target of the present invention is a sputtering target material made of a sintered body of a metal oxide joined, that is, bonded, to a substrate with solder (for example, In metal).

[0011] The metal oxide constituting the sputtering target material of the present invention preferably contains one or more elements selected from the group consisting of metal elements such as In, Sn, Ga, Zn, W, Ta, Nb, Sr, Ti, and Zr, and may further contain a semimetal element such as Si or a nonmetal element.

[0012] For example, metal oxides constituting the sputtering target material of the present invention include In—Sn—O, In—Ti—O, In—Ga—Zn—O, In—Zn—Sn—O, In—Ga—Zn—Sn—O, Ga—Zn—O, In—Zn—O, I-W—O, I-Zn-W—O, Zn—O, Sn—Ba—O, Sn—Zn—O, Sn—Ti—O, Sn—Ca—O, Sn—Mg—O, Zn—Mg—O, Zn—Ge—O, Zn—Ca—O, Zn—Sn—Ge—O, Cu ２ O, CuAlO ２ ,CuGaO ２ , CuInO ２ Examples of metal oxides include:

[0013] The metal oxide is preferably a composite metal oxide containing In and Sn, and a sputtering target having a sputtering target material made of a sintered composite metal oxide containing In and Sn is called an ITO target or an ITO sputtering target. Furthermore, the metal oxide may be a composite metal oxide containing In, Ga, and Zn, and a sputtering target having a sputtering target material made of a sintered composite metal oxide containing In, Ga, and Zn is called an IGZO target or an IGZO sputtering target.

[0014] The sputtering target material of the present invention preferably has an average peeled area ratio of 6.5% or less, from the viewpoint of suppressing the amount of peeling of the sputtering target material. Furthermore, the average peeled area ratio is more preferably 6.0% or less, even more preferably 5.0% or less, particularly preferably 4.0% or less, even more particularly preferably 3.0% or less, even more particularly preferably 2.0% or less, even particularly preferably 1.0% or less, even more particularly preferably 0.5% or less, and most preferably 0%. The average peeled area ratio may typically be 0.01% to 6.5%, 0.1% to 6%, 1% to 5%, 1.5% to 4.5%, or 2% to 4%.

[0015] Here, the average peeled area ratio can be determined as follows. First, a 5.0 mm wide carbon tape (manufactured by Nisshin EM Co., Ltd.) is attached to the center of the surface (sputtering surface) of a sputtering target material of the present invention that has been subjected to the surface treatment of the present invention described below, and then the carbon tape is quickly peeled off. At this time, the peeled sputtering target material adheres to the carbon tape. Then, the carbon tape is observed using a scanning electron microscope (SU5000, manufactured by Hitachi High-Technologies Corporation, accelerating voltage: 20.0 kV, measurement magnification: 100x), and SEM images of five fields of view are taken.

[0016] Next, after removing boundary particles at the outermost periphery of each SEM image, particle analysis software (Nippon Steel Sumikin Technology Co., Ltd.: Particle Analysis Version 3.5) is used to draw and fill in the area of ​​the peeled sputtering target material with a color different from the color of the carbon tape background.The area of ​​the peeled sputtering target material is then filled in and binarized.At this time, a conversion value is set so that one pixel is displayed in μm units.

[0017] Thereafter, the area of ​​the region of the peeled sputtering target material and the area of ​​the entire carbon tape surface are calculated using particle analysis software, and the percentage of the area of ​​the region of the peeled sputtering target material relative to the area of ​​the entire carbon tape surface is determined as the area ratio. The average value of the area ratios obtained for each of the five fields of view of the SEM images is then taken as the average peeled area ratio for the sputtering target material of the present invention.

[0018] The sputtering target material of the present invention preferably has an arithmetic mean roughness Ra of the sputtering surface of 0.20 μm or more, from the viewpoint of maintaining a high particle capturing ability in the non-erosion region.

[0019] Here, the arithmetic mean roughness Ra is specified in JIS B 0601:2013 and is measured using a surface roughness measuring instrument (SJ-210, manufactured by Mitutoyo Corporation). The arithmetic mean roughness Ra is measured at five points on the surface (sputtering surface) of the sputtering target material, and the arithmetic mean value thereof is defined as the arithmetic mean roughness Ra of the sputtering target material.

[0020] The sputtering target of the present invention is characterized by comprising a sputtering target material made of a sintered body of a metal oxide, having a damage area ratio of 2.0% or less as calculated by image analysis, and an arithmetic mean roughness Ra of the sputtering surface of 0.20 μm or more. With this configuration, the sputtering target of the present invention can suppress the amount of peeling while ensuring a high surface roughness Ra.

[0021] Here, the metal oxide sintered body and the arithmetic mean roughness Ra are as described above, and therefore a description thereof will be omitted.

[0022] The sputtering target material of the present invention preferably has a damage area ratio of 2.0% or less, as calculated by image analysis described below, from the viewpoint of reducing particles during sputtering. Furthermore, the damage area ratio is more preferably 1.5% or less, even more preferably 1.0% or less, particularly preferably 0.5% or less, even more particularly preferably 0.3% or less, even more particularly preferably 0.2% or less, even particularly preferably 0.1% or less, and most preferably 0%. The damage area ratio may typically be 0.01% to 2.0%, 0.1% to 1.0%, 0.3% to 0.5%, or 0.5% to 1.0%.

[0023] The image analysis described above involves observing the side of the sputtering target material with an optical microscope (Keyence Corporation: VK-8700, measurement magnification: 200x), and drawing and coloring in areas where cracks have occurred (hereinafter referred to as areas corresponding to microcracks) using image analysis software (Keyence Corporation: VK-III). Note that areas corresponding to microcracks are areas that are likely to peel off later.

[0024] The damage area ratio can be determined as follows. First, the cut surface of the sputtering target material is polished in stages using emery paper #180, #400, and #1000, and finally buffed to a mirror finish. Then, the cut surface is regarded as the side surface of the sputtering target material, and a cross-sectional photograph of the sputtering surface of the sputtering target material is observed by observing the cut surface using an optical microscope (Keyence Corporation: VK-8700, measurement magnification: 200x). Optical microscope photographs of 20 consecutive fields of view are then taken across the cut surface, and the 20 consecutive optical microscope photographs are joined together to create a cross-sectional photograph of the sputtering surface of the sputtering target material with a length of 9.6 mm (see FIG. 1(a)). The observation depth from the sputtering surface of the sputtering target material was 150 μm, and the observation length of the sputtering surface was 9.6 mm (9600 μm), so 150 μm × 9.6 mm (9600 μm) = 1,440,000 μm ２ is used as the reference area for calculating the damage area ratio.

[0025] Next, areas corresponding to microcracks visible in the cross-sectional photograph of the sputtering surface of the prepared sputtering target material are drawn and color-filled using image analysis software (Keyence Corporation: VK-III) (see the hatched area in Figure 1(b)). The optical microscope photograph in which the areas corresponding to the microcracks are filled in is recognized and binarized. At this time, the conversion value is set so that one pixel is displayed in μm units.

[0026] Here, as shown in Fig. 2(a), there are cases where the microcrack does not penetrate the sputtering surface of the sputtering target material. In such cases, a perpendicular line is drawn from the end of the microcrack that does not penetrate toward the sputtering surface of the sputtering target material (see the dashed line in Fig. 2(b)), and the area surrounded by the microcrack and the perpendicular line is defined as the area corresponding to the microcrack.

[0027] Thereafter, the area of ​​the region corresponding to the microcrack is calculated using image analysis software, and the percentage of the area of ​​the region corresponding to the microcrack relative to the reference area is calculated as the area ratio, which is then defined as the damage area ratio in the sputtering target material of the present invention.

[0028] The sputtering target of the present invention is characterized in that it comprises a sputtering target material having a maximum height roughness Rz of the sputtering surface of 2.0 μm or more, or a maximum cross-sectional height Rt of 3.0 μm or more. With this configuration, the sputtering target of the present invention can suppress the amount of peeling.

[0029] In terms of capturing particles, the sputtering target material of the present invention preferably has a maximum height roughness Rz of 2.0 μm or more on the sputtering surface. The maximum height roughness Rz may typically be 2.0 μm to 8.0 μm.

[0030] The maximum height roughness Rz, like the arithmetic mean roughness Ra, is specified in JIS B 0601:2013 and is measured using a surface roughness measuring instrument (SJ-210, manufactured by Mitutoyo Corporation). The maximum height roughness Rz is measured at five locations on the sputtering surface of the sputtering target material, and the arithmetic mean value thereof is defined as the maximum cross-sectional height Rt of the sputtering target material.

[0031] In the sputtering target material of the present invention, it is preferable from the viewpoint of capturing particles that the maximum cross-sectional height Rt of the sputtering surface is 3.0 μm or more. The maximum cross-sectional height Rt may typically be 3.0 μm to 12.0 μm.

[0032] The maximum cross-sectional height Rt, like the arithmetic mean roughness Ra, is specified in JIS B 0601:2013 and is measured using a surface roughness measuring instrument (SJ-210, manufactured by Mitutoyo Corporation). The maximum cross-sectional height Rt of the surface (sputtering surface) of the sputtering target material is measured.

[0033] In addition, the sputtering target material used in the sputtering target of the present invention contains In when the sintered body of the metal oxide is 100 mass %.２ O ３ In the sputtering target material of the present invention, when the sintered body of the metal oxide is taken as 100 mass %, the content of In is 0.2 mass % or more and 98 mass % or less in terms of In. ２ O ３ The content of 0.2 mass % or more and 98 mass % or less in terms of In conversion is preferred in terms of the properties that are widely used in transparent conductive films and oxide semiconductor applications. ２ O ３ The content may be 5% by mass or more and 97% by mass or less, or 10% by mass or more and 90% by mass or less, calculated as a converted amount.

[0034] Nitric acid, perchloric acid, and hydrogen peroxide were added to the sputtering target material, which was then decomposed by heating to form a solution. The solution was then analyzed using an ICP optical emission spectrometer (Agilent Technologies: 720 ICP-OES) to determine the amount of In in the solution. ２ O ３ The converted In content can be measured.

[0035] The sputtering target material of the present invention is characterized in that it has a flat plate or cylindrical shape. With this configuration, the sputtering target material of the present invention may have a flat plate or cylindrical shape, but is not limited to a flat plate or cylindrical shape and can have any shape.

[0036] As described above, the sputtering target of the present invention is a sputtering target material made of a sintered body of a metal oxide joined, i.e., bonded, to a substrate with solder (e.g., In metal). Here, the substrate may be of various sizes and shapes, and in particular, a flat substrate is called a backing plate. Also, a cylindrical substrate is called a backing tube.

[0037] Furthermore, the sputtering target of the present invention preferably has a nodule area ratio of 0.8% or less as calculated by image analysis described below, since this allows for a reduction in particles during sputtering. Furthermore, the nodule area ratio is more preferably 0.5% or less.

[0038] The nodule area ratio calculated by the image analysis described above can be determined as follows. First, sputtering is performed continuously for 48 hours using a sputtering target under the sputtering conditions described below, and then an external photograph of the surface (sputtering surface) of the sputtering target is taken using a digital camera with 12 million pixels or more. Then, in the external photograph, areas corresponding to the nodules formed on the surface (sputtering surface) of the sputtering target are drawn and color-filled using image analysis software (Particle Analysis Version 3.5, manufactured by Nippon Steel & Sumikin Technology Co., Ltd.).

[0039] =Sputtering conditions= Equipment: DC magnetron sputtering equipment, exhaust system cryopump, rotary pump. Ultimate vacuum: 3 x 10 －６ Pa Sputtering pressure: 0.4 Pa Oxygen partial pressure: 1×10 －３ Pa ・Input power time: 2W / cm ３

[0040] The external appearance photograph in which the area corresponding to the nodule is filled in is recognized and binarized. At this time, the conversion value is set so that one pixel is displayed in μm units.

[0041] Thereafter, the area of ​​the region corresponding to the nodule and the area of ​​the entire sputtering surface are calculated using image analysis software, and the percentage of the area of ​​the region corresponding to the nodule relative to the area of ​​the entire sputtering surface is determined as the area ratio. Note that this area ratio is the value displayed as "area ratio" on the image analysis software. The obtained area ratio value is then defined as the nodule area ratio in the sputtering target of the present invention.

[0042] A method for producing the sputtering target of the present invention described above will be described below.

[0043] The method for manufacturing a sputtering target of the present invention is the method for manufacturing a sputtering target of the present invention described above, and includes the steps of grinding an oxide sintered body and cleaning it with ultrasonic waves, bonding the processed and cleaned oxide sintered body to a substrate, and dry ice blasting the oxide sintered body bonded to the substrate.

[0044] First, raw material metal oxide powders are weighed in desired proportions, pulverized and mixed, and the pulverized and mixed mixture is made into a slurry. The mixture slurry is then poured into a mold, and the resulting molded body is fired to obtain an oxide sintered body. The method for pulverizing and mixing the raw material metal oxide powders may be either dry pulverization or wet pulverization.

[0045] The oxide sintered body thus obtained is subjected to grinding and ultrasonic cleaning. Specifically, first, the surface of the oxide sintered body, i.e., the surface to be sputtered, is ground using a surface grinder equipped with a grinding wheel.

[0046] Examples of the grain size of the grinding stone used in grinding using a surface grinder include F4 to F220, F230 to F1200, and #240 to #8000 as specified in JIS R 6001: 1998. #240 to #600 is particularly preferred.

[0047] In addition, the oxide sintered body that has been ground using a surface grinder is further ground using, for example, a fabric grindstone. A fabric grindstone is a grindstone that is three-dimensionally bonded to a fibrous body (fabric) by, for example, attaching the grindstone to the fibrous body (fabric). The grain size of the grindstone is relatively non-uniform, and the distance between the grindstones is also relatively non-uniform. Since the grindstones are bonded to the fibrous body (fabric), the pressure applied to the grindstones can be alleviated.

[0048] Examples of types of fibrous bodies for fabric grindstones include those made of microfiber, nonwoven fabric, cotton yarn, flannel material, and polyester fiber.

[0049] Examples of the material of the fabric grindstone include WA (white alumina), A (brown alumina), HA (crushed alumina), PA (light pink alumina), GC (green silicon carbide), C (black silicon carbide), and Z (alumina zirconia). GC (green silicon carbide) is particularly preferred.

[0050] Examples of the grain size of the fabric grindstone include F4 to F220, F230 to F1200, and #240 to #8000 as specified in JIS R 6001: 1998. #240 to #600 is particularly preferred.

[0051] The ground oxide sintered body is ultrasonically cleaned. Specifically, an ultrasonic cleaner is used to apply vibrations (ultrasonic waves) to the ground oxide sintered body, thereby removing the polishing debris generated and attached during the grinding process. Pure water can be used as the cleaning water for the ultrasonic cleaning. The ultrasonic cleaning may be performed repeatedly while changing the cleaning water. The frequency of the ultrasonic waves used in the ultrasonic cleaning may be 1 kHz to 200 kHz, 28 kHz to 200 kHz, or 28 kHz to 100 kHz. The cleaning time in the ultrasonic cleaning may be 1 second to 1 hour, or 1 second to 10 minutes. After the ultrasonic cleaning, the oxide sintered body is dried using an air blower, a dryer, a heat dryer, a reduced pressure dryer, or a vacuum dryer.

[0052] Next, the processed oxide sintered body and a substrate are joined together. Specifically, the oxide sintered body that has been subjected to grinding and ultrasonic cleaning is joined, i.e., bonded, to the substrate with solder (e.g., In metal).

[0053] Here, the material of the solder used to join the oxide sintered body of the present invention to the substrate is not particularly limited, but examples include low-melting-point solders such as In metal, In—Sn metal, or In alloy metal in which trace metal components are added to In. The melting point of the low-melting-point solder is 150 to 200° C., so when filling the solder, the solder is heated to 150 to 300° C. to melt it.

[0054] Then, the oxide sintered body bonded to the substrate is subjected to dry ice blasting. Specifically, surface treatment by dry ice blasting, in which dry ice particles are sprayed onto the surface (sputtering surface) of the oxide sintered body, is carried out in accordance with the dry ice blasting conditions described below. The sprayed dry ice particles collide with the surface (sputtering surface) of the oxide sintered body, thereby removing microcracks present on the surface (sputtering surface) of the oxide sintered body and also removing processing chips, dust, and dirt present on the surface (sputtering surface) of the oxide sintered body.

[0055] Dry ice blasting conditions: Average particle size of dry ice particles: 0.1 to 1 mm Gas medium (N ２ ) Gauge pressure (pressure): 0.1 to 0.6 MPa Wear rate: 20 to 100% Processing speed: 0.8 to 142.9 mm / sec Processing angle: 0 to 20° Nozzle temperature: ≧20°C Distance between target and blast nozzle: 10 to 140 mm

[0056] The dry ice particles sprayed from the blast nozzle are crushed and pulverized dry ice, and their shape does not have to be spherical, and they may be irregular. The size of the dry ice particles is not particularly limited as long as they can be sprayed together with the gas medium. The average particle size of the dry ice particles is preferably 0.1 to 1 mm.

[0057] The gas medium used to eject the dry ice particles is not particularly limited as long as it does not affect the surface of the sputtering target material of the present invention. For example, air, nitrogen, or other inert gases can be used. The gauge pressure (pressure) of the gas medium is preferably 0.1 to 0.6 MPa.

[0058] Furthermore, the method of ejecting the dry ice particles and gas medium can be carried out in the same manner as general shot blasting, by simply mixing the dry ice particles with the gas medium that is ejected at a predetermined pressure.

[0059] The "wear rate" in the dry ice blasting conditions refers to the feed rate at which the dry ice is pushed out. The "treatment rate" in the dry ice blasting conditions refers to the speed at which the blast nozzle is moved over the oxide sintered body. The "treatment angle" in the dry ice blasting conditions refers to the angle of the blast nozzle with respect to the surface (sputtering surface) of the oxide sintered body. Here, the treatment angle is 0 degrees when the blast nozzle is positioned perpendicular to the surface (sputtering surface) of the oxide sintered body, and the treatment angle is 90 degrees when the blast nozzle is positioned parallel to the surface (sputtering surface) of the oxide sintered body.

[0060] The oxide sintered body bonded to the substrate in this manner is subjected to dry ice blasting to obtain the sputtering target of the present invention.

[0061] The oxide film of the present invention is characterized by being formed using the sputtering target of the present invention. Due to this constitution, the oxide film of the present invention is a uniform oxide film.

[0062] The method for producing an oxide film of the present invention also includes a step of forming an oxide film by sputtering the sputtering target of the present invention.

[0063] The sputtering target of the present invention is set in a sputtering device, and sputtering is carried out under the following sputtering conditions to form the oxide film of the present invention.

[0064] =Sputtering conditions= Equipment: DC magnetron sputtering equipment, exhaust system cryopump, rotary pump. Ultimate vacuum: 3 x 10 －６ Pa Sputtering pressure: 0.4 Pa Oxygen partial pressure: 1×10 －３ Pa ・Input power time: 2W / cm ３

[0065] In this specification, when "X to Y" (X and Y are any numbers) is expressed, unless otherwise specified, it means "X or more and Y or less", and also means "preferably larger than X" or "preferably smaller than Y". Furthermore, when "X or more" (X is any number) or "Y or less" (Y is any number), it also means "preferably larger than X" or "preferably smaller than Y".

[0066] The sputtering target of the present invention and the method for producing the same can suppress the amount of peeling while ensuring a high surface roughness Ra.

[0067] 1A is an example of a cross-sectional photograph of the sputtering surface of a sputtering target material according to the present invention, and FIG. 1B is a schematic diagram showing a region corresponding to a microcrack in FIG. 1A. 1A is another example of a cross-sectional photograph of the sputtering surface of a sputtering target material according to the present invention, and FIG. 1B is a schematic diagram showing a perpendicular line drawn from an end of a microcrack in FIG. 1A toward the sputtering surface of the sputtering target material.

[0068] The sputtering target according to the embodiment of the present invention will be further described below with reference to the following examples, although the present invention is not limited to these examples.

[0069] (Example 1) ITO (In ２ O ３ : SnO ２ A plate material having a density of 99.8% and consisting of a mixture of SiO 2 and SiO 3 (weight ratio: 90:10 (mass %)) was fired, and a sputtering target material according to Example 1 having a diameter of 4 inches and a thickness of 6 mm was produced from this plate material.

[0070] The surface (sputtering surface) of the sputtering target material was ground using a surface grinder equipped with a grinding stone (grit size: #200), and further surface grinding was performed using a surface grinder equipped with a fabric grinding stone (fiber type: nylon, grinding stone material: GC (green silicon carbide), grinding stone grain size: #320). After surface grinding, the sputtering target material was immersed in a cleaning tank containing pure water, and the surface (sputtering surface) of the sputtering target material was ultrasonically cleaned and dried.

[0071] The dried sputtering target material was bonded to a substrate (copper backing plate) using solder containing In metal. After bonding, the surfaces and peripheral surfaces of the sputtering target material and substrate were polished with sandpaper to remove solder that had protruded from the surfaces and peripheral surfaces of the sputtering target material and substrate, and solder that had adhered to the substrate. In addition, the surfaces of the sputtering target material and substrate were wiped with isopropyl alcohol (IPA) to remove shavings.

[0072] Then, the surface (sputtering surface) of the sputtering target material was subjected to surface treatment by dry ice blasting processing in which dry ice particles were sprayed according to the dry ice blasting conditions described below, and the surface (sputtering surface) of the sputtering target material was further wiped with isopropyl alcohol (IPA) to obtain the sputtering target of Example 1.

[0073] Dry ice blasting conditions: Average particle size of dry ice particles: 0.3 mm Gas medium (N ２ ) Gauge pressure (pressure): 0.3 MPa Wear rate: 70% Treatment speed: 20.0 mm / sec Treatment angle: 0 degrees Nozzle temperature: 25°C Distance between target and blast nozzle: 30 mm In Table 1, the gas medium (N ２ ) is shown as "pressure".

[0074] (Example 2) In Example 2, a sputtering target according to Example 2 was obtained by carrying out the same manufacturing method as in Example 1, except that the grit size of the grinding stone of the surface grinder was changed to #400, and the wear rate of the dry ice blasting conditions was changed to 30% and the processing speed to 142.9 mm / sec.

[0075] (Example 3) In Example 3, a manufacturing method similar to that of Example 1 was carried out, except that the gauge pressure (pressure) of the gas medium (N2) in the dry ice blasting conditions was changed to 0.6 MPa, and a sputtering target according to Example 3 was obtained.

[0076] (Example 4) In Example 4, a sputtering target according to Example 4 was obtained by carrying out the same manufacturing method as in Example 1, except that the grit size of the grinding stone of the surface grinder was changed to #400, the wear rate of the dry ice blasting conditions was changed to 30%, and the processing speed was changed to 0.8 mm / sec.

[0077] Example 5 In Example 5, a sputtering target according to Example 5 was obtained by carrying out the same manufacturing method as in Example 1, except that the processing speed of the dry ice blasting conditions was changed to 142.9 mm / sec.

[0078] Example 6 In Example 6, a sputtering target according to Example 6 was obtained by carrying out the same manufacturing method as in Example 1, except that the processing speed of the dry ice blasting conditions was changed to 0.8 mm / sec.

[0079] Comparative Example 1 In Comparative Example 1, a sputtering target according to Comparative Example 1 was obtained by carrying out the same manufacturing method as in Example 1, except that the dry ice processing was not carried out.

[0080] (Comparative Example 2) In Comparative Example 2, the same manufacturing method as in Example 1 was carried out, except that the grain size of the grinding stone of the surface grinder was changed to #400 and dry ice processing was not performed, to obtain a sputtering target according to Comparative Example 2.

[0081] (Comparative Example 3) In Comparative Example 3, the grain size of the grinding stone of the surface grinding machine was changed to #1000, the surface grinding process was performed with a #1000 sponge grinding stone instead of a fabric grinding stone, and dry ice processing was not performed. The same manufacturing method as in Example 1 was carried out, and a sputtering target according to Comparative Example 3 was obtained.

[0082] (Comparative Example 4) In Comparative Example 4, the gas medium (N ２ A sputtering target according to Comparative Example 4 was obtained by carrying out the same production method as in Example 1, except that the gauge pressure (pressure) of the sputtering target 1 was changed to 0.1 MPa.

[0083] (Comparative Example 5) In Comparative Example 5, the grain size of the grinding stone of the surface grinding machine was changed to #1000, the surface grinding was performed with a #1000 sponge grinding stone instead of a fabric grinding stone, and the wear rate of the dry ice blasting conditions was changed to 30% and the processing speed was changed to 0.8 mm / sec. Except for this, a manufacturing method similar to that of Example 1 was carried out to obtain a sputtering target according to Comparative Example 5.

[0084] (Comparative Example 6) In Comparative Example 6, the grain size of the grinding stone of the surface grinding machine was changed to #1000, the surface was ground with a #1000 sponge grinding stone instead of a fabric grinding stone, and the gas medium (N ２ A sputtering target according to Comparative Example 6 was obtained by carrying out the same manufacturing method as in Example 1, except that the gauge pressure (pressure) of the sputtering target 1 was changed to 0.6 MPa, the wear rate was changed to 30%, and the processing speed was changed to 142.9 mm / sec.

[0085] (Comparative Example 7) In Comparative Example 7, the grain size of the grinding stone of the surface grinding machine was changed to #1000, the surface was ground with a #1000 sponge grinding stone instead of a fabric grinding stone, and the gas medium (N ２ A sputtering target according to Comparative Example 7 was obtained by carrying out the same manufacturing method as in Example 1, except that the gauge pressure (pressure) of the sputtering target 1 was changed to 0.6 MPa, the wear rate was changed to 30%, and the processing speed was changed to 0.8 mm / sec.

[0086] Table 1 shows a list of the methods for manufacturing the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7.

[0087]

[0088] The following physical properties were measured for the sputtering targets obtained in Examples 1 to 6 and Comparative Examples 1 to 7. The measured physical properties and the methods for measuring the physical properties are shown below, and the measurement results are shown in Table 2.

[0089] <Elemental Analysis> Nitric acid, perchloric acid, or hydrogen peroxide was added to the sample as necessary, and the sample was decomposed by heating to form a solution. The weight of each element (weight of metal elements such as In, Sn, Ga, Zn, W, Ta, Nb, Sr, Ti, and Zr, metalloid elements such as Si, and non-metallic elements) was measured using an ICP optical emission spectrometer (Agilent Technologies: 720 ICP-OES).

[0090] <Average Peeling Area Ratio> A 5 ​​mm wide carbon tape (manufactured by Nissin EM Co., Ltd.) was attached to the center of the surface (sputtering surface) of each of the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7, and then the carbon tape was quickly peeled off. At this time, the peeled sputtering target material adhered to the carbon tape. The carbon tape was then observed using a scanning electron microscope (SU5000, manufactured by Hitachi High-Technologies Corporation, accelerating voltage: 20.0 kV, measurement magnification: 100x), and SEM images of five fields of view were taken.

[0091] Next, boundary particles at the outermost periphery of each SEM image were removed, and then particle analysis software (Nippon Steel Sumikin Technology Co., Ltd.: Particle Analysis Version 3.5) was used to draw and fill in the area of ​​the peeled sputtering target with a color different from the background of the carbon tape. The area of ​​the peeled sputtering target was then filled in and binarized. At this time, a conversion value was set so that one pixel was displayed in μm units.

[0092] Thereafter, the area of ​​the peeled sputtering target region and the area of ​​the entire carbon tape surface were calculated using particle analysis software, and the percentage of the area of ​​the peeled sputtering target region relative to the area of ​​the entire carbon tape surface was determined as the area ratio. The average value of the area ratios obtained for each of the five fields of view of the SEM images was taken as the average peeled area ratio for the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7, and was evaluated as follows: ◯ (GOOD): average peeled area ratio ≦ 6.5% × (BAD): average peeled area ratio > 6.5%

[0093] <Damage Area Ratio> The cut surfaces of the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7 were polished stepwise using emery paper #180, #400, and #1000, and finally buffed to a mirror finish. The cut surfaces were regarded as the side surfaces of the sputtering target materials, and the sputtering surfaces of the sputtering target materials were observed using an optical microscope (Keyence Corporation: VK-8700, measurement magnification: 200x). Specifically, optical microscope photographs of 20 consecutive fields of view were taken across the cut surfaces, and the optical microscope photographs of the 20 consecutive fields of view were joined together to create a cross-sectional photograph of the sputtering surface of the sputtering target material, corresponding to a length of 9.6 mm (see FIG. 1(a)). The observation depth from the sputtering surface of the sputtering target material was 150 μm, and the observation length of the sputtering surface was 9.6 mm (9600 μm), so 150 μm × 9.6 mm (9600 μm) = 1,440,000 μm ２ was used as the reference area for calculating the damage area ratio.

[0094] Next, areas corresponding to microcracks visible in the cross-sectional photograph of the sputtering surface of the prepared sputtering target material were drawn and color-filled using image analysis software (Keyence Corporation: VK-III) (see the hatched area in Figure 1(b)). The optical microscope photograph in which the areas corresponding to the microcracks were filled in was recognized and binarized. At this time, the conversion value was set so that one pixel was displayed in μm units.

[0095] Furthermore, as shown in Figure 2(a), when a microcrack does not penetrate the sputtering surface of the sputtering target material, a perpendicular line was drawn from the end of the microcrack that did not penetrate toward the sputtering surface of the sputtering target material (see the dashed line in Figure 2(b)), and the area surrounded by the microcrack and the perpendicular line was defined as the area corresponding to the microcrack.

[0096] Thereafter, the area of ​​the region corresponding to the microcrack was calculated using image analysis software, and the percentage of the area of ​​the region corresponding to the microcrack relative to the reference area was calculated as the area ratio. The obtained area ratio was then taken as the damage area ratio of the sputtering target material of the present invention and evaluated as follows: ◯ (GOOD): Damage area ratio ≦ 2.0% × (BAD): Damage area ratio > 2.0%

[0097] <Arithmetic mean roughness Ra> The arithmetic mean roughness Ra is specified in JIS B 0601:2013 and was measured using a surface roughness measuring instrument (SJ-210, manufactured by Mitutoyo Corporation). The arithmetic mean roughness Ra was measured at five points on the surface (sputtering surface) of the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7, and the arithmetic mean value was taken as the arithmetic mean roughness Ra of the sputtering target, which was evaluated as follows: ◯ (GOOD): Arithmetic mean roughness Ra≦0.20 × (BAD): Arithmetic mean roughness Ra>0.20

[0098] <Maximum height roughness Rz> The maximum height roughness Rz, like the arithmetic mean roughness Ra, is specified in JIS B 0601:2013 and was measured using a surface roughness measuring instrument (SJ-210, manufactured by Mitutoyo Corporation). The maximum height roughness Rz was measured at five locations on the surface (sputtering surface) of the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7, and the arithmetic mean value was taken as the maximum height roughness Rz of the sputtering target, which was evaluated as follows: ◯ (GOOD): Maximum height roughness Rz≦2.0 × (BAD): Maximum height roughness Rz>2.0

[0099] <Maximum cross-sectional height Rt> The maximum cross-sectional height Rt, like the arithmetic mean roughness Ra, is specified in JIS B 0601:2013 and was measured using a surface roughness measuring instrument (SJ-210 / manufactured by Mitutoyo Corporation). The maximum cross-sectional heights Rt were measured at five locations on the surface (sputtering surface) of the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7, and the arithmetic mean value was taken as the maximum cross-sectional height Rt of the sputtering target, which was evaluated as follows: ◯ (GOOD): Maximum cross-sectional height Rt≦3.0 × (BAD): Maximum cross-sectional height Rt>3.0

[0100] <Nodule Area Ratio> Sputtering was performed continuously for 48 hours using the sputtering targets according to Examples 1 to 6 and Comparative Examples 1 to 7 under the sputtering conditions described below, and then an external photograph of the surface (sputtering surface) of the sputtering target was taken using a digital camera with 12 million pixels or more. In the external photograph, areas corresponding to nodules formed on the surface (sputtering surface) of the sputtering target were drawn and filled with color using image analysis software (Nippon Steel Sumikin Technology Co., Ltd.: Particle Analysis Version 3.5). The external photograph with the filled-in areas corresponding to the nodules was recognized and binarized. In this case, a conversion value was set so that one pixel was displayed in μm units.

[0101] =Sputtering conditions= Equipment: DC magnetron sputtering equipment, exhaust system cryopump, rotary pump. Ultimate vacuum: 3 x 10 －６ Pa Sputtering pressure: 0.4 Pa Oxygen partial pressure: 1×10 －３ Pa ・Input power time: 2W / cm ３

[0102] Thereafter, the area of ​​the region corresponding to the nodule and the area of ​​the entire sputtering surface were calculated using image analysis software, and the percentage of the region corresponding to the nodule relative to the area of ​​the entire sputtering surface was determined as the area ratio. The obtained area ratio value was then taken as the area ratio of nodules formed on the sputtering target surface (sputtering surface), and was evaluated as follows: 〇〇 (VERY GOOD): 0.5%≦nodule area ratio 〇 (GOOD): 0.5%<nodule area ratio≦0.8% × (BAD): nodule area ratio>0.8%

[0103] <Overall Evaluation> A specimen that did not receive a single evaluation of "× (BAD)" in any of the above-mentioned average peeled area ratio, damaged area ratio, arithmetic mean roughness Ra, maximum height roughness Rz, maximum cross-sectional height Rt, and nodule area ratio was evaluated as "◯ (GOOD)," and a specimen that received an evaluation of "× (BAD)" in any one of the items was evaluated as "× (BAD)."

[0104]

[0105] As shown in Table 2, the sputtering target materials of the sputtering targets according to Examples 1 to 6 have an average peeling area ratio of 6.5% or less and an arithmetic mean roughness Ra of the sputtering surface of 0.20 μm or more. This means that the amount of peeling of the sputtering target material can be suppressed while maintaining a high particle capturing ability in the non-erosion region, and it was confirmed that the surface (sputtering surface) was in a clean state while maintaining surface roughness.

[0106] The sputtering target materials of the sputtering targets according to Examples 1 to 6 have a damage area ratio of 2.0% or less and an arithmetic mean roughness Ra of the sputtering surface of 0.20 μm or more, so that it is possible to reduce particles during sputtering while maintaining a high particle capturing ability in the non-erosion region. Therefore, although a grindstone with a coarse grit was used to ensure surface roughness, it was confirmed that the damage remaining on the surface (sputtering surface) was small.

[0107] The sputtering target materials of the sputtering targets according to Examples 1 to 6 have a maximum height roughness Rz of 2.00 μm or more, or a maximum cross-sectional height Rt of 3.00 μm or more, and therefore it has been confirmed that they have irregularities that capture particles.

[0108] The inventions disclosed in this specification include, in addition to the configurations of each invention and embodiment, those specified by changing these partial configurations to other configurations disclosed in this specification, to the extent applicable, or those specified by adding other configurations disclosed in this specification to these configurations, or those specified as higher-level concepts specified by deleting these partial configurations to the extent that partial effects can be obtained.

[0109] The sputtering target according to the present invention suppresses the amount of peeling while maintaining a high surface roughness Ra, and is therefore suitable as a sputtering target capable of suppressing the generation of nodules and particles. Furthermore, use of the sputtering target according to the present invention can reduce the occurrence of defective products during film formation. This leads to the sustainable management and efficient use of natural resources, and the achievement of decarbonization (carbon neutrality).

Claims

1. A sputtering target comprising a sputtering target material made of a sintered body of a metal oxide, the sputtering target material having an average peeled area rate of 6.5% or less and an arithmetic mean roughness Ra of the sputtering surface of 0.20 μm or more.

2. A sputtering target comprising a sputtering target material made of a sintered body of a metal oxide, the damage area ratio calculated by image analysis being 2.0% or less, and the arithmetic mean roughness Ra of the sputtering surface being 0.20 μm or more.

3. A sputtering target according to claim 1 or 2, characterized in that the sputtering surface has a maximum height roughness Rz of 2.0 μm or more, or a maximum cross-sectional height Rt of 3.0 μm or more.

4. The sputtering target according to claim 1 or 2, characterized in that the sputtering target material contains one or more elements selected from the group consisting of metal elements such as In, Sn, Ga, Zn, W, Ta, Nb, Sr, Ti, and Zr, semi-metal elements such as Si, and non-metal elements.

5. The sputtering target material contains In when the sintered body of the metal oxide is 100 mass %. ２ O ３ The sputtering target according to claim 1 or 2, characterized in that it contains from 0.2 mass % to 98 mass % in terms of aluminium.

6. The sputtering target according to claim 1 or 2, characterized in that the sputtering target material is a composite metal oxide containing In and Sn.

7. The sputtering target according to claim 1 or 2, characterized in that the sputtering target material is in the shape of a plate or a cylinder.

8. A method for producing a sputtering target according to claim 1 or 2, comprising the steps of: grinding an oxide sintered body and cleaning it by ultrasonic waves; bonding the processed and cleaned oxide sintered body to a substrate; and dry ice blasting the oxide sintered body bonded to the substrate.

9. An oxide film formed by using the sputtering target according to claim 1 or 2.

10. A method for producing an oxide film, comprising the step of forming an oxide film by sputtering the sputtering target according to claim 1 or 2.

Images