Sputtering target for magnetic material, sputtering target assembly for magnetic material, and method for manufacturing sputtering target for magnetic material

Abstract

Provided are a sputtering target for a magnetic material in which redeposition film peeling can be effectively suppressed, a sputtering target assembly for a magnetic material, and a method for manufacturing a sputtering target for a magnetic material. Provided is a sputtering target for a magnetic material, the sputtering target having a sputtering region and a non-sputtering region, wherein the surface of the non-sputtering region has a plurality of rounded protrusions, and the plurality of protrusions include protrusions connected via a connection part and / or protrusions not connected via a connection part.

Description

Sputtering target for magnetic material, sputtering target assembly for magnetic material, and method for manufacturing sputtering target for magnetic material

[0001] The present invention relates to a sputtering target for a magnetic material, a sputtering target assembly for a magnetic material, and a method for manufacturing a sputtering target for a magnetic material, and mainly relates to a sputtering target for manufacturing films for HDDs.

[0002] For example, the layers of hard disks that employ perpendicular magnetic recording systems are made of materials based on ferromagnetic metals such as Co, Fe, and Ni, and the recording layers are often made of composite materials consisting of ferromagnetic alloys, such as Co-Cr, Co-Pt, Co-Cr-Pt, and Fe-Pt, which have Co or Fe as their main components, and non-magnetic inorganic materials. Thin films for magnetic recording media such as hard disks are often produced by sputtering targets containing the above materials, due to their high productivity.

[0003] Sputtering is a technique for forming a thin film on the surface of a substrate by sputtering the surface of a sputtering target, which serves as the sputtering source, with accelerated argon ions, releasing particles (sputter particles) from the sputtering target and depositing the sputter particles on the surface of a substrate that has been placed in an opposing position.

[0004] Some of the sputtered particles may redeposit at specific locations on the sputtering target to form a laminate (also called a redeposited film). If this redeposited film peels off from the sputtering target, it can cause arcing (abnormal discharge) during sputtering, increase the number of particles during sputtering, and cause problems such as contamination of the thin film, resulting in a lower product yield.

[0005] To address this problem, Patent Document 1 discloses that the region of the sputtering target where the redeposition film is formed is roughened by blasting with glass beads. It also discloses that this makes it possible to prevent the redeposition film from peeling off from the roughened surface. Patent Document 2 also discloses that the sputtering target is roughened. Patent Document 2 also discloses that the region to be roughened is within a range from the outer periphery (0%) of the sputtering target to a position 2 to 13% in the center direction, and / or within a range from the center (0%) to a position 12 to 33% in the outer periphery direction.

[0006] Japanese Patent Laid-Open No. 4-301074 Japanese Patent Laid-Open No. 2018-141202

[0007] Both Patent Documents 1 and 2 merely mention controlling the arithmetic mean roughness Ra, and there is room for improvement in terms of suppressing peeling of the redeposition film.

[0008] Therefore, an object of an embodiment of the present invention is to provide a sputtering target for magnetic materials, a sputtering target assembly for magnetic materials, and a method for manufacturing a sputtering target for magnetic materials that can effectively suppress peeling of a redeposition film.

[0009] The above-mentioned problems are solved by the present invention, which is specified as follows: (1) A sputtering target for a magnetic material having a sputtering region and a non-sputtering region, wherein the surface of the non-sputtering region has a plurality of rounded convex portions, and the plurality of convex portions include convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion. (2) The sputtering target for a magnetic material according to (1), in which the surface of the non-sputtering region has a developed area ratio Sdr of 4.5 or more. (3) The sputtering target for a magnetic material according to (1) or (2), in which the surface roughness Sa of the non-sputtering region is 10 to 40 μm. (4) The sputtering target for a magnetic material according to any of (1) to (3), in which the maximum height Sz of the non-sputtering region is 100 to 250 μm. (5) The sputtering target for a magnetic material according to any one of (1) to (4), wherein the root mean square height Sq of the non-sputtered region is 3 to 45 μm. (6) The sputtering target for a magnetic material according to any one of (1) to (5), wherein the composition includes at least one of Co, Pt, Fe, Ru, Cr, Ti, Si, Zr, B, C, N, Al, O, Mg, Zn, Ag, Cu, Ni, Ta, Nb, V, W, Mn, Bi, Ge, and Ir. (7) A sputtering target assembly for a magnetic material, comprising: the sputtering target for a magnetic material according to any one of (1) to (6), and a backing plate bonded to the sputtering target for a magnetic material. (8) A method for manufacturing a sputtering target for a magnetic material having a sputtering region and a non-sputtering region, the method comprising a step of forming a plurality of rounded convex portions on a surface of the non-sputtering region, the plurality of convex portions including convex portions connected via connecting portions and / or convex portions not connected via connecting portions.

[0010] According to the embodiments of the present invention, it is possible to provide a sputtering target for a magnetic material, a sputtering target assembly for a magnetic material, and a method for manufacturing a sputtering target for a magnetic material, which are capable of effectively suppressing peeling of a redeposition film.

[0011] 1(A) and 1(B) are plan views each schematically showing a disk-shaped sputtering target.

[0034] FIGS. 1(A) and 1(B) are SEM photographs of the non-sputtering region surface for illustrating the first convex portion, the second convex portion, and the connecting portion.

[0035] FIGS. 3(A) and 3(B) are schematic diagrams of an example of a structure including the first convex portion, the second convex portion, and the connecting portion, respectively.

[0036] FIGS. 4(A) and 4(B) are schematic diagrams of an example of a structure including the first convex portion, the second convex portion, the third convex portion, and the connecting portion, respectively.

[0037] FIGS. 5(A) and 5(B) are schematic diagrams of an example of a structure including the first convex portion, the second convex portion, the third convex portion, the fourth convex portion, and the connecting portion, respectively.

[0038] FIGS. 8(A) and 8(B) are SEM photographs of the non-sputtering region surface for illustrating the first convex portion and the second convex portion.

[0039] FIGS. 8(B) and 8(C) are schematic diagrams of an example of a structure including the first convex portion, the second convex portion, the third convex portion, the fourth convex portion, and the connecting portion, respectively. Fig. 8(C) is an SEM photograph of the non-sputtered region surface of Example 3. Fig. 8(D) is an SEM photograph of the non-sputtered region surface of Example 4. Fig. 8(E) is an SEM photograph of the non-sputtered region surface of Example 5. (A) is an SEM photograph of the appearance of the sample surface after lacquer spray application in Example 3. (B) is an SEM photograph of the appearance of the sample surface after cutting out a 1 mm square lattice in Example 3. (C) is an SEM photograph of the appearance of the sample surface after a peel test in Example 3.

[0012] Next, embodiments of the present invention will be described in detail with reference to the drawings. It should be understood that the present invention is not limited to the following embodiments, and that appropriate design changes and improvements may be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0013] <Sputtering target for magnetic material> The shape of the sputtering target for magnetic material according to the embodiment of the present invention is not particularly limited, and may be a flat plate (including a disk or rectangular plate), a cylindrical shape, or any other shape. In this specification, the sputtering target for magnetic material may also be simply referred to as a sputtering target.

[0014] The sputtering target according to this embodiment is used, for example, to form magnetic recording layers and thin films in HDDs. The material of the sputtering target according to this embodiment is not particularly limited, but may include at least one of Co, Pt, Fe, Ru, Cr, Ti, Si, Zr, B, C, N, Al, O, Mg, Zn, Ag, Cu, Ni, Ta, Nb, V, W, Mn, Bi, Ge, and Ir. Alternatively, the sputtering target may include an alloy containing at least one of Co, Pt, Fe, Ru, Cr, Ti, Si, Zr, B, C, N, Al, Mg, Zn, Ag, Cu, Ni, Ta, Nb, V, W, Mn, Bi, Ge, and Ir. The sputtering target may also be made of a material containing an alloy particle phase and a non-magnetic material. The non-magnetic material may be one or more selected from carbon, oxides, nitrides, and carbides.

[0015] The sputtering target according to the embodiment of the present invention mainly has a front surface, a back surface, and a side surface. The front surface is subjected to a roughening treatment described below. Therefore, the front surface has a sputtering region and a non-sputtering region. The sputtering region is a region on the surface of the sputtering target that is sputtered by bombarding accelerated argon ions, and the non-sputtering region is a region on the surface of the sputtering target other than the sputtering region. This non-sputtering region is a region where some of the sputtered particles redeposit to form a redeposited film, and in order to effectively suppress peeling of the redeposited film, the sputtering target according to the embodiment of the present invention is subjected to a very distinctive roughening treatment.

[0016] Specific examples of the sputtering region and the non-sputtering region of the sputtering target according to the embodiment of the present invention are shown in Figures 1(A) and 1(B), which are plan views schematically showing sputtering targets 10a and 10b formed in a disk shape, respectively.

[0017] In the sputtering target 10a shown in FIG. 1A, only the peripheral portion of the surface of the sputtering target 10a, where the redeposition film is formed, is a non-sputtering region 12a, while the remaining regions, including the central portion, are sputtering regions 11a. The peripheral non-sputtering region 12a is preferably formed with a uniform width of a predetermined size along the circumferential direction of the surface of the sputtering target 10a. The area ratio of the peripheral non-sputtering region 12a is not particularly limited as long as it covers at least the position where the redeposition film is formed. Furthermore, the sputtering target 10a may have a non-sputtering region that is roughened not only on the peripheral portion of the surface as described above, but also on the entire or part of the side surface. Even in this case, the entire or part of the side surface non-sputtering region has the same characteristics as the non-sputtering region described below.

[0018] In the sputtering target 10b shown in FIG. 1B, the peripheral portion of the surface of the sputtering target 10b where the redeposition film is formed is a non-sputtering region 12b, and the central portion of the surface is also a non-sputtering region 13b. The area other than these non-sputtering regions 12b and 13b is a sputtering region 11b. The peripheral non-sputtering region 12b is preferably formed with a uniform width of a predetermined size along the circumferential direction of the surface of the sputtering target 10b. The area ratios of the central non-sputtering region 13b and the peripheral non-sputtering region 12b are not particularly limited as long as they cover at least the position where the redeposition film is formed. Furthermore, only the central portion of the surface of the sputtering target 10b may be roughened. Furthermore, the sputtering target 10b may have a non-sputtering region where the entire surface or a portion of the side surface is roughened, in addition to the peripheral and central portions of the surface as described above. In this case, the entire surface or a portion of the side surface has the same characteristics as the non-sputtering region described below.

[0019] The surface of the non-sputtering region of the sputtering target according to an embodiment of the present invention has a plurality of rounded protrusions, and the plurality of protrusions includes protrusions connected via connecting portions and / or protrusions not connected via connecting portions. This configuration allows for the formation of favorable irregularities on the surface of the non-sputtering region, ensuring a sufficient surface area. This improves the adhesion of the redeposited film formed in the non-sputtering region, effectively suppressing peeling of the redeposited film. As a result, particle contamination during sputtering is suppressed, improving the product yield. The plurality of protrusions and connecting portions will be described in detail below with reference to the drawings.

[0020] FIG. 2 shows an SEM photograph (magnification: 100x) of the surface of the non-sputtering region of a sputtering target according to Example 1, which will be described later, as an example of a sputtering target according to an embodiment of the present invention. Here, first and second convex portions are described as the multiple convex portions, but there are also multiple other convex portions. The surface of the non-sputtering region has a rounded first convex portion 21 and a rounded second convex portion 22, and the first convex portion 21 and the second convex portion 22 are connected via a connecting portion 23. A plurality of structures including the first convex portion 21, the second convex portion 22, and the connecting portion 23 are formed on the surface of the non-sputtering region. The structures including the first convex portion 21, the second convex portion 22, and the connecting portion 23 are formed by laser processing the surface of the sputtering target, as will be described later, and are structures in which the first convex portion 21, the second convex portion 22, and the connecting portion 23 are continuous with each other. The multiple structures including the first convex portion 21, the second convex portion 22, and the connecting portion 23 may exist singly, multiple structures may be adjacent to each other, the structures may partially overlap each other, or a combination thereof may be used. The shape of the first convex portion 21 may be the same as or different from the shape of the second convex portion 22. The structures may be formed on a portion of the surface of the non-sputtering region. Furthermore, if multiple structures are formed over the entire surface of the non-sputtering region while partially overlapping each other, this is preferable because the surface area of ​​the non-sputtering region is further increased and the adhesion of the redeposited film formed on the non-sputtering region is further improved.

[0021] The first convex portion 21 and the second convex portion 22 each have a rounded shape. The first convex portion 21 and the second convex portion 22 may have a rounded shape like a sphere, a rounded shape like an ellipsoid or an elongated ellipsoid (prolate ellipsoid), or another rounded shape, or may have a plurality of rounded shapes formed by combining a plurality of spheres.

[0022] The shape and size of the connecting portion 23 are not particularly limited as long as it has a shape that connects the first convex portion 21 and the second convex portion 22, and it may be a shape that extends with a uniform thickness, or a shape that extends with an uneven thickness, may extend in a straight line, may extend in a curved line, may extend in two or three directions, or may extend in more directions.

[0023] 3(A) and 3(B) are schematic diagrams showing an example of a structure including a first convex portion 21, a second convex portion 22, and a connecting portion 23 when observing the surface of a non-sputtering region of a sputtering target according to an embodiment of the present invention. In Fig. 3(A), the first convex portion 21 and the second convex portion 22 have similar shapes, while in Fig. 3(B), the first convex portion 21 and the second convex portion 22 have different shapes or sizes. In Fig. 3(A) and 3(B), the structure including the first convex portion 21, the second convex portion 22, and the connecting portion 23 has a shape in which the first convex portion 21 and the second convex portion 22, which have a rounded shape such as a sphere or an ellipse, are integrally formed at the end of the connecting portion 23.

[0024] The surface of the non-sputtering region of the sputtering target according to an embodiment of the present invention may further include a third convex portion. Figures 4(A) and 4(B) are schematic diagrams illustrating an example of a structure including a first convex portion 21, a second convex portion 22, a third convex portion 24, and a connecting portion 23, as observed from the surface of the non-sputtering region. In Figures 4(A) and 4(B), the structure including the first convex portion 21, the second convex portion 22, the third convex portion 24, and the connecting portion 23 has a shape in which the first convex portion 21, the second convex portion 22, and the third convex portion 24, each having a rounded shape such as a spherical or elliptical shape, are integrally formed at the end of the connecting portion 23. In Figure 4(A), the connecting portion 23 is a single piece, with the first convex portion 21 integrally formed at one end and the second convex portion 22 and the third convex portion 24 integrally formed at the other end. In Figure 4 (B), the connecting portion 23 branches off midway to have a total of three ends, and the first convex portion 21, the second convex portion 22, and the third convex portion 24 are integrally formed at each end.

[0025] The surface of the non-sputtering region of the sputtering target according to an embodiment of the present invention may further include a fourth convex portion. Figures 5(A) and 5(B) are schematic diagrams illustrating an example of a structure including a first convex portion 21, a second convex portion 22, a third convex portion 24, a fourth convex portion 25, and a connecting portion 23, as observed from the surface of the non-sputtering region. In Figures 5(A) and 5(B), the structure including the first convex portion 21, the second convex portion 22, the third convex portion 24, the fourth convex portion 25, and the connecting portion 23 has a shape in which the first convex portion 21, the second convex portion 22, the third convex portion 24, and the fourth convex portion 25, each having a rounded shape such as a spherical or elliptical shape, are integrally formed at the end of the connecting portion 23. In Figure 5(A), the connecting portion 23 is a single piece, with the first convex portion 21 and the fourth convex portion 25 integrally formed at one end and the second convex portion 22 and the third convex portion 24 integrally formed at the other end. In Figure 5(B), the connecting portion 23 branches off midway to form a total of four ends, with a first convex portion 21, a second convex portion 22, a third convex portion 24, and a fourth convex portion 25 integrally formed at each end. Furthermore, the shapes are not limited to those shown in Figures 3(A) to 5(B), and the structure may have even more convex portions, such as a fifth convex portion, a sixth convex portion, etc. With this configuration, various types of irregularities are formed on the surface of the non-sputtering region, further increasing the surface area. This further improves the adhesion of the redeposited film formed in the non-sputtering region, making it possible to better suppress peeling of the redeposited film.

[0026] The size of the convex portions, such as the first convex portion 21 and the second convex portion 22, is not particularly limited, but the longest diameter is preferably 10 μm or more, and more preferably 30 μm or more. The size of the convex portions, such as the first convex portion 21 and the second convex portion 22, is typically 10 to 100 μm. The longest diameter of the convex portions, such as the first convex portion 21 and the second convex portion 22, can be measured by observing the non-sputtered region at 100x magnification using a scanning electron microscope (Hitachi High-Tech S-3700N). When a straight line is drawn through the convex portion on an acquired SEM photograph, the longest diameter can be defined as the length on the convex portion of the longest line passing through the convex portion. When measuring with a scanning electron microscope, the accelerating voltage, current value (irradiation current value), brightness, and contrast can be adjusted to clearly visualize the image.

[0027] The distance between the convex portions, such as the distance between the first convex portion 21 and the second convex portion 22, is not particularly limited, but may typically be 10 to 100 μm, or may be 20 to 80 μm. The distance between the convex portions can be measured by taking an SEM photograph, similar to the size of the convex portions described above. The distance between the convex portions can be defined as the length of a straight line connecting the centers of the circumscribing circles of the convex portions on the taken SEM photograph.

[0028] FIG. 6 shows an SEM photograph (magnification: 100x) of the surface of the non-sputtering region of a sputtering target according to Example 5, which will be described later, as another example of a sputtering target according to an embodiment of the present invention. The surface of the non-sputtering region has a rounded first convex portion 21 and a rounded second convex portion 22. The first convex portion 21 and the second convex portion 22 are not connected via a connecting portion, and the shape of the first convex portion 21 is different from the shape of the second convex portion 22. A plurality of structures including such first convex portions 21 and second convex portions 22 are formed on the surface of the non-sputtering region. Unlike the embodiment shown in FIG. 2 , these convex portions are not connected to each other via a connecting portion, and exist independently on the surface of the non-sputtering region. Furthermore, the surface of the non-sputtering region may be configured such that the convex portions exist independently, or such independently existing convex portions may be mixed with structures formed by convex portions connected to each other via a connecting portion. With this configuration, the surface area of ​​the non-sputtered region increases, improving the adhesion of the redeposited film formed on the non-sputtered region.

[0029] Fig. 7 is a schematic diagram of an example of the first convex portion 21 and the second convex portion 22 when observing the surface of the non-sputtered region for the example shown in Fig. 6. As shown in Fig. 7, the rounded first convex portion 21 and the rounded second convex portion 22 are adjacent to each other, the first convex portion 21 and the second convex portion 22 are not connected via a connecting portion, and the shape of the first convex portion 21 is different from the shape of the second convex portion 22.

[0030] The sizes of the independently existing first convex portions 21 and second convex portions 22 are not particularly limited, but each preferably has a longest diameter of 10 μm or more, more preferably 30 μm or more. Furthermore, the sizes of the independently existing first convex portions 21 and second convex portions 22 are typically 10 to 100 μm. Furthermore, the distance between the independently existing first convex portions 21 and second convex portions 22 is not particularly limited, but may typically be 10 to 100 μm, or 20 to 80 μm, between adjacent convex portions.

[0031] The developed area ratio Sdr of the surface of the non-sputtered region 12a is preferably 4.5 or greater. The developed area ratio Sdr represents the degree to which the developed area (surface area) of a given region has increased relative to the area of ​​that given region; for example, the developed area ratio Sdr of a completely flat surface is 0. If the developed area ratio Sdr of the surface of the non-sputtered region 12a is 4.5 or greater, the roughness of the non-sputtered region 12a is further increased, thereby increasing the contact area with the redeposited film and improving the adhesion of the redeposited film. The developed area ratio Sdr of the surface of the non-sputtered region 12a is more preferably 5.0 or greater. There is no particular upper limit to the developed area ratio Sdr of the surface of the non-sputtered region 12a, but it may be 10.0 or less, or even 9.0 or less. The developed area ratio Sdr of the surface of the non-sputtered region 12a can be measured using a laser microscope in accordance with ISO-25178.

[0032] The surface roughness Sa of the non-sputtering region 12a is preferably 10 to 40 μm. When the surface roughness Sa of the non-sputtering region 12a is 10 μm or more, the roughness of the non-sputtering region 12a is further increased, thereby improving the adhesion of the redeposited film. When the surface roughness Sa of the non-sputtering region 12a exceeds 40 μm, this means that there are too many protruding portions, which are portions that protrude away from the surface of the sputtering target. The increased number of protruding portions may induce arcing. The surface roughness Sa of the non-sputtering region 12a is more preferably 15 to 35 μm, and even more preferably 18 to 33 μm. The surface roughness Sa of the non-sputtering region 12a can be measured using a laser microscope in accordance with ISO-25178. Furthermore, while the average surface roughness Ra is evaluated using a "line," the surface roughness Sa is evaluated using a "plane." When measuring average roughness Ra, the measurement results vary depending on which part is set as the measurement target. For example, if the measurement target is set along a predetermined area and Ra is measured, Ra will be smaller than when the measurement target is set across the predetermined area. Therefore, by using surface roughness Sa, the variation in Sa depending on the setting position of the measurement target is reduced, thereby improving the accuracy of control of the surface shape of the sputtering target. As a result, the quality stability of the sputtering target can be improved.

[0033] The maximum height Sz of the non-sputtered region 12a is preferably 100 to 250 μm. If the maximum height Sz of the non-sputtered region 12a is 100 μm or more, the difference in elevation of the non-sputtered region 12a becomes large, and when a redeposited film is formed in the non-sputtered region 12a, the redeposited film is more likely to be secured at high and low positions in the non-sputtered region 12a. Therefore, the redeposited film is less likely to peel off from the non-sputtered region. If the maximum height Sz of the non-sputtered region 12a exceeds 250 μm, there is a high possibility that very large convex portions will be present. This may therefore be a factor in inducing arcing during sputtering. The maximum height Sz of the non-sputtered region 12a is more preferably 110 to 210 μm, and even more preferably 120 to 200 μm. The maximum height Sz of the non-sputtered region 12a can be measured using a laser microscope in accordance with ISO-25178.

[0034] The root-mean-square height Sq of the non-sputtered region 12a is preferably 3 to 45 μm. Since Sq represents the standard deviation of roughness, a small Sq indicates small roughness itself. Therefore, it is preferable that the root-mean-square height Sq of the non-sputtered region 12a be 3 μm or more. If the root-mean-square height Sq of the non-sputtered region 12a is 45 μm or less, it indicates a small standard deviation of surface roughness, indicating uniform unevenness, and is advantageous in terms of preventing arcing. If the root-mean-square height Sq of the non-sputtered region 12a exceeds 45 μm, it indicates large variation in surface height, making it more likely that specifically high positions will exist. This increases the likelihood of arcing. The root-mean-square height Sq of the non-sputtered region 12a is more preferably 15 to 40 μm, and even more preferably 18 to 39 μm. The root mean square height Sq of the non-sputtered region 12a can be measured using a laser microscope in accordance with ISO-25178.

[0035] The above-mentioned Sdr, Sa, Sz, and Sq can be measured using a laser microscope (Keyence VK-X3000, head model VK-X3100). The procedure is as follows. In the case of the VK-X3000, a 10x objective lens, 1.5x digital zoom, and 24x screen magnification are used to acquire a 360x (10x x 1.5x x 24x) image. Laser confocal is selected as the measurement method. The analysis software used is the multi-file analysis application version 3.3.1.85 included with the VK-X3000. First, select surface roughness measurement as the measurement mode, and then select the desired roughness parameters and area. When selecting the area, specify a range (896 μm x 672 μm) from the acquired image (360x image). The above-mentioned area is determined by performing this range specification operation on the laser microscope. Next, the analysis is performed using the following filter settings: When setting up surface shape correction, use "plane tilt correction." Note that "plane tilt correction" is used whether the measurement target is a non-sputtered area on the surface or side of a sputtering target. <Filter settings> Filter type: Gaussian S-filter: None F-operation: Enabled L-filter: None End effect correction: Checked Note that the surface area is measured using a function called volumetric area measurement under the following conditions. <Surface area measurement conditions> Measurement mode: Convexity Height threshold setting: Set so that all unevenness in the measurement field is included in the measurement. Select the height threshold setting button, which is one of the operation screens of the Keyence VK-X3000, and drag the bar on the screen that switches upwards so that it covers all the spectrum shown in black, to set so that all unevenness in the measurement field is included in the measurement. Ignore minute unevenness: None Ignore minute areas: Enabled Include top and bottom surfaces in surface area calculation: None

[0036] The configuration of the non-sputtering region described above has been described for non-sputtering region 12a of sputtering target 10a shown in FIG. 1(A), but is not limited to this and may also be included in non-sputtering regions 12b and 13b of sputtering target 10b shown in FIG. 1(B), or in non-sputtering regions of sputtering targets according to other embodiments of the present invention.

[0037] <Sputtering Target Assembly> The sputtering target according to the embodiment of the present invention may be bonded to a backing plate as needed to form a sputtering target assembly. The sputtering target assembly can be mounted in a sputtering apparatus for use. Indium or indium tin can be used as the brazing material. The sputtering target according to the embodiment of the present invention may be mounted directly in a sputtering apparatus for use without using a backing plate. The material of the backing plate is not particularly limited, and examples thereof include Cu, Ti, Mo, and alloys containing at least one of these (e.g., Cu-Ni-Si alloys (e.g., C18000, etc.), CuZn alloys, and CuCr alloys). It is preferable that the material of the backing plate has high thermal conductivity, and from this perspective, Cu is suitable.

[0038] <Method for Manufacturing a Sputtering Target> A method for manufacturing a sputtering target according to an embodiment of the present invention will be described in detail below. In the method for manufacturing a sputtering target according to an embodiment of the present invention, first, raw materials for forming a sintered body are prepared. The raw materials for the sintered body may be a powder containing at least one of Co, Pt, Fe, Ru, Cr, Ti, Si, Zr, B, C, N, Al, O, Mg, Zn, Ag, Cu, Ni, Ta, Nb, V, W, Mn, Bi, Ge, and Ir, or may be a powder containing an alloy or ceramic containing at least one of Co, Pt, Fe, Ru, Cr, Ti, Si, Zr, B, C, N, Al, Mg, Zn, Ag, Cu, Ni, Ta, Nb, V, W, Mn, Bi, Ge, and Ir. Alternatively, the raw materials for the sintered body may be a powder containing an alloy particle phase and a nonmagnetic material. The purity of these raw materials is usually 2N (99% by mass) or higher, preferably 3N (99.9% by mass) or higher, and more preferably 4N (99.99% by mass) or higher. If the purity is lower than 2N, the sintered body will contain a large amount of impurities, which can cause problems such as the desired physical properties not being obtained (for example, a decrease in the transmittance of the formed thin film, an increase in resistance, and the generation of particles due to arcing). These raw materials can be appropriately prepared based on the composition and purity of the desired sintered body.

[0039] Next, the powders of these raw materials are pulverized and mixed. The pulverization and mixing of the powders of the raw materials can be performed using a ball mill using ceramic balls.

[0040] The mixture obtained by mixing and pulverizing as described above is then hot-pressed to obtain a sintered body. Sintering conditions can be appropriately selected depending on the composition of the sintered body.

[0041] The sintered body is then machined on a lathe to obtain a target of a desired shape. The surface roughness after lathe machining is preferably set to 1 μm or less (Ra) so as not to affect laser machining.

[0042] Next, under atmospheric pressure, a non-sputtered region of the sintered body is laser processed to form a surface having a rounded first convex portion and a rounded second convex portion in the non-sputtered region, the first convex portion and the second convex portion being connected via a connecting portion, or the first convex portion and the second convex portion not being connected via a connecting portion, and the shape of the first convex portion being different from the shape of the second convex portion.

[0043] Furthermore, in the non-sputtering region of the sintered body, the shape, size, number, and surface Sdr, Sa, Sz, and Sq of the first convex portions, second convex portions, and connecting portions can be appropriately adjusted by the output of the laser irradiation, the scanning speed of the laser light, multiple scanning of the same location, etc. More specifically, by appropriately adjusting each condition in the following laser processing conditions, the shape, size, number, and surface Sdr, Sa, Sz, and Sq of the first convex portions, second convex portions, and connecting portions in the non-sputtering region of the sputtering target according to an embodiment of the present invention can be controlled to a desired configuration.

[0044] In this embodiment, the sintered body is not heated using a separate heating device during the roughening treatment (laser irradiation). This is because the roughening treatment is performed under atmospheric pressure, and heating would facilitate oxidation of the sputtering target. Furthermore, it is not anticipated that any particular treatment will be performed to remove residual stress in the sputtering target before, after, or during the roughening treatment. Furthermore, the back surface of the sputtering target is not roughened. This is because performing the roughening treatment on the back surface could reduce the strength of the sputtering target.

[0045] (Laser Processing Conditions) Laser processing power: 15 to 25 W Scanning speed: 150 to 1000 mm / s Number of scans at the same location: 1 to 10 times Frequency: 140 to 400 kHz Scanning pitch: 0.05 to 0.18 mm Based on the above conditions, laser processing may be performed by first drawing a cross pattern (0° angle) as "Layer 1," and then drawing a cross pattern (layer 2) without rotation (0° rotation) or rotated by a predetermined angle, overlapping the cross pattern with the laser, thereby drawing a linear pattern at 0° or a predetermined angle. Laser processing may also be performed a desired number of times. As described above, sputtering targets according to embodiments of the present invention can be manufactured. However, because the above conditions basically depend on the target composition (due to differences in thermal conductivity and melting point), it is necessary to find the conditions through trial and error for the composition.

[0046] In this embodiment, further roughening of the non-sputtered region after roughening treatment is not anticipated. For example, physical roughening methods such as bead blasting or chemical roughening methods such as chemical etching are not anticipated. For example, further bead blasting of the non-sputtered region after roughening treatment would result in residual blasting media. Note that, as long as the desired surface condition can be achieved, roughening of the non-sputtered region may be performed by other methods than laser irradiation. However, roughening the non-sputtered region by laser irradiation can achieve a surface of the non-sputtered region 12a that is free of ZrO2 and SiC. The presence of ZrO2 and SiC on the surface of the non-sputtered region 12a means, for example, that elements of the blasting media are present on the surface of the non-sputtered region 12a. The absence of ZrO2 and SiC on the surface of the non-sputtered region 12a prevents elements of the blasting media from being mixed into the thin film and suppresses arcing during sputtering. Furthermore, if the composition of the sputtering target does not contain Al2O3, Al2O3 is not present. The presence of Al2O3 on the surface of the non-sputtering region 12a even when the composition of the sputtering target does not contain Al2O3 means, for example, that elements of the blasting media are present on the surface of the non-sputtering region 12a. The absence of Al2O3 on the surface of the non-sputtering region 12a can prevent elements of the blasting media from being mixed into the thin film and can also suppress arcing during sputtering.

[0047] <Film formation method using a sputtering target> Using the sputtering target according to the embodiment of the present invention, it is possible to form a thin film that mainly constitutes a magnetic recording medium. Specifically, a sputtering device is used to sputter the surface of the sputtering target with accelerated argon ions, causing particles (sputtered particles) to be emitted from the sputtering target, and the sputtered particles are deposited on the surface of a substrate previously positioned opposite the sputtering target, thereby forming a thin film on the surface of the substrate. Sputtering conditions can be appropriately set depending on the desired film thickness, composition, etc.

[0048] A portion of the sputtered particles redeposits on the non-sputtering region of the sputtering target to form a redeposited film. In the sputtering target according to an embodiment of the present invention, the surface of the non-sputtering region has a plurality of rounded convex portions, and the plurality of convex portions includes convex portions that are connected via connecting portions and / or convex portions that are not connected via connecting portions, so that the adhesion of the redeposited film formed on the non-sputtering region is improved and peeling of the redeposited film is effectively suppressed.

[0049] Examples of the present invention are given below, but these examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

[0050] Examples 1 to 7 - Manufacturing of Sputtering Targets Sputtering targets according to Examples 1 to 7 were manufactured using the following manufacturing method. First, raw materials for the sintered body were prepared. The raw materials for the sintered body were powders containing Co, Cr, Pt, B, O, Ti, and Si (Examples 1 to 5), powders containing Co, Pt, B, O, Ti, and Si (Example 6), and powders containing Co, Pt, Ru, Ti, O, and Si (Example 7). The purity of each of these raw materials was 3N (99.9% by mass). Next, these raw material powders were pulverized in a ball mill using beads, and the resulting mixture was hot-pressed to obtain a sintered body. Next, the sintered body was machined using a lathe to obtain a disk-shaped target. Next, under atmospheric pressure, laser processing was performed on the non-sputtered region of the sintered body to form a surface having a rounded first convex portion and a rounded second convex portion, the first convex portion and the second convex portion being connected via a connecting portion, or the first convex portion and the second convex portion not being connected via a connecting portion, and the shape of the first convex portion being different from the shape of the second convex portion. For the laser processing, a cross pattern was first drawn with a laser (0° angle) as "Layer 1," and then, as "Layer 2," a cross pattern was drawn with a laser either without rotation (0° rotation) or rotated 45°, overlapping with the laser, thereby forming a linear pattern at 0° or 45° angles. Note that in Example 4, only Layer 1 was laser processed. The laser processing conditions for Layer 1 and Layer 2 are shown below. Tables 1 and 2 also show the laser processing conditions for each Example.

[0051] (Laser processing conditions for layer 1) Laser processing output: 20 W Scanning speed: 200 to 400 mm / s Number of scans at the same location: 1 Frequency: 140 to 220 kHz Scanning pitch: 0.1 mm

[0052] (Laser processing conditions for layer 2) Laser processing power: 20 W Scanning speed: 200 to 800 mm / s Number of scans at the same location: 1 Frequency: 140 to 220 kHz Scanning pitch: 0.1 to 0.131 mm

[0053] SEM Photographs: SEM photographs of the non-sputtered regions of Examples 1 to 7 were taken using a Hitachi High-Tech S-3700N. The obtained SEM photographs confirmed that the surfaces of the non-sputtered regions of Examples 1 to 7 each had multiple rounded convex portions, including convex portions connected via connecting portions and / or convex portions not connected via connecting portions. Figures 8(A) to 8(E) show SEM photographs (magnification: 100x) of Examples 1 to 5, respectively. When taking the SEM photograph of Figure 8, the acceleration voltage was set to 15 kV, and the current value (irradiation current value) was set to 84,000 nA.

[0054] Sdr, Sa, Sz, Sq For the sputtering targets of Examples 1 to 7, the developed area ratio Sdr of the non-sputtered region, the surface roughness Sa, the maximum height Sz, and the root mean square height Sq were measured using a laser microscope (Keyence VK-X3000, head model VK-X3100). The measurement procedure was as described above.

[0055] Peel Test A peel test was conducted on Examples 1 to 5 to confirm the adhesion of the redeposited film. The peel test was conducted in accordance with JIS-K5400 (checkerboard tape method). A commercially available lacquer spray was applied to each non-sputtered area and allowed to dry for at least 6 hours. Subsequently, slits were made in the coating film formed by applying the lacquer spray with a cutter to create 100 1 mm square grids (square grids). Furthermore, cellophane tape was applied to the surface of the slit coating film, and when the cellophane tape was peeled off, the degree of grid peeling was evaluated on a scale of 0 to 10 as specified in JIS-K5400. In all of Examples 1 to 5, each cut was fine and smooth on both sides, and no peeling was observed at the intersections of the cuts or between the squares. Therefore, a score of 10 was given. These results confirmed that Examples 1 to 5 were able to effectively suppress redeposited film peeling. As examples of the peel test method, Fig. 9(A) shows a photograph of the appearance of the sample surface after lacquer spray application in Example 3, Fig. 9(B) shows a photograph of the appearance of the sample surface after cutting out a 1 mm square grid in Example 3, and Fig. 9(C) shows a photograph of the appearance of the sample surface after the peel test in Example 3. Table 2 shows the evaluation results.

[0056]

[0057]

[0058] <Discussion> In all of the sputtering targets of Examples 1 to 5, the surface of the non-sputtering region had a plurality of rounded convex portions, and the plurality of convex portions had a shape including convex portions connected via connecting portions and / or convex portions not connected via connecting portions. This made it possible to form favorable unevenness on the surface of the non-sputtering region and ensure surface area, improving the adhesion of the redeposited film formed in the non-sputtering region and effectively suppressing peeling of the redeposited film. Furthermore, in Examples 6 and 7, similar to Examples 1 to 5, the surface of the non-sputtering region had a plurality of rounded convex portions, and the plurality of convex portions had a shape including convex portions connected via connecting portions and / or convex portions not connected via connecting portions, and it is believed that peeling of the redeposited film can similarly be effectively suppressed.

[0059] 10a, 10b Sputtering target 11a, 11b Sputtering region 12a, 12b, 13b Non-sputtering region 21 First convex portion 22 Second convex portion 23 Connecting portion 24 Third convex portion 25 Fourth convex portion

Claims

1. A sputtering target for a magnetic material, having a sputtering region and a non-sputtering region, wherein the surface of the non-sputtering region has a plurality of rounded convex portions, and the plurality of convex portions include convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion.

2. The sputtering target for a magnetic material according to claim 1, wherein the developed area ratio Sdr of the surface of the non-sputtering region is 4.5 or more.

3. The sputtering target for a magnetic material according to claim 1 or 2, wherein the surface roughness Sa of the non-sputtering region is 10 to 40 μm.

4. The sputtering target for a magnetic material according to claim 1 or 2, wherein the maximum height Sz of the non-sputtering region is 100 to 250 μm.

5. The sputtering target for a magnetic material according to claim 1 or 2, wherein the root mean square height Sq of the non-sputtering region is 3 to 45 μm.

6. The sputtering target for a magnetic material according to claim 1 or 2, comprising at least one of Co, Pt, Fe, Ru, Cr, Ti, Si, Zr, B, C, N, Al, O, Mg, Zn, Ag, Cu, Ni, Ta, Nb, V, W, Mn, Bi, Ge, and Ir in the composition.

7. A sputtering target assembly for a magnetic material, comprising the sputtering target for a magnetic material according to claim 1 or 2, and a backing plate joined to the sputtering target for a magnetic material.

8. A method for manufacturing a sputtering target for a magnetic material, having a sputtering region and a non-sputtering region, the method including a step of forming a plurality of rounded convex portions on the surface of the non-sputtering region, and the plurality of convex portions include convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion.

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