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

Abstract

Provided are a sputtering target for magnetic materials, a sputtering target assembly for magnetic materials, and a method for producing a sputtering target for magnetic materials, with which peeling of a redeposited film can be satisfactorily suppressed. A sputtering target for a magnetic material, which has a sputtering region and a non-sputtering region, and which is characterized in that the surface of the non-sputtering region has a plurality of protrusions having roundness, and the plurality of protrusions include protrusions that are connected via a connection portion and / or protrusions that are not connected via the connection portion.

Description

Technical Field

[0001] This invention relates to sputtering targets for magnetic materials, sputtering target assemblies for magnetic materials, and methods for manufacturing sputtering targets for magnetic materials, primarily to sputtering targets suitable for manufacturing films for hard disk drives (HDDs). Background Technology

[0002] In hard disks employing perpendicular magnetic recording, materials based on strongly magnetic metals such as Co, Fe, and Ni are often used in the recording layers. These materials are typically composites made of strongly magnetic alloys (Co-Cr, Co-Pt, Co-Cr-Pt, Fe-Pt, etc.) and non-magnetic inorganic materials, with Co and Fe as the main components. From a productivity standpoint, the thin films of such magnetic recording media, including hard disks, are mostly fabricated by sputtering onto sputtering targets composed of the aforementioned materials.

[0003] Sputtering is a method in which accelerated argon ions are used to sputter the surface of a sputtering target, which serves as the sputtering source, causing particles (sputtered particles) to be released from the sputtering target and deposited on the surface of a substrate pre-positioned in opposite locations, thereby forming a thin film on the surface of the substrate.

[0004] Sometimes, a portion of the sputtered particles re-attach to designated areas of the sputtering target, forming a laminate (also known as a redeposition film). When this redeposition film peels off from the sputtering target, it can cause defects such as arcing (abnormal discharge) during sputtering, increased particle contamination in the film, and reduced yield.

[0005] Regarding this problem, Patent Document 1 discloses a method of roughening the surface of the area of ​​the sputtering target for which a redeposited film is to be formed by using a sandblasting process with glass beads. It further discloses that this method can suppress the peeling of the redeposited film from the roughened surface. Patent Document 2 also discloses a method of roughening the sputtering target. Furthermore, Patent Document 2 discloses that the roughened area is a range extending from the outer periphery (0%) of the sputtering target towards the center to a position of 2-13% and / or from the center (0%) towards the outer periphery to a position of 12-33%.

[0006] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 4-301074 Patent Document 2: Japanese Patent Application Publication No. 2018-141202 Summary of the Invention

[0007] The problem that the invention aims to solve Both Patent Documents 1 and 2 only describe controlling the arithmetic mean roughness Ra, which has room for improvement from the viewpoint of suppressing the peeling of redeposited films.

[0008] Therefore, the technical problem of the embodiments 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 the peeling of redeposited films.

[0009] Solution for solving the problem The above-mentioned technical problems are solved by the present invention as described below.

[0010] (1) A sputtering target for magnetic materials having a sputtering region and a non-sputtering region, wherein the surface of the non-sputtering region has a plurality of rounded protrusions, the plurality of protrusions including protrusions connected by a connecting portion and / or protrusions not connected by a connecting portion.

[0011] (2) The sputtering target for magnetic materials according to (1), wherein the surface area ratio of the non-sputtered region is 4.5 or more.

[0012] (3) The sputtering target for magnetic materials according to (1) or (2), wherein the surface roughness Sa of the non-sputtering region is 10 to 40 μm.

[0013] (4) A sputtering target for magnetic materials according to any one of (1) to (3), wherein the maximum height Sz of the non-sputtering region is 100 to 250 μm.

[0014] (5) A sputtering target for magnetic materials according to any one of (1) to (4), wherein the root mean square height Sq of the non-sputtering region is 3 to 45 μm.

[0015] (6) A sputtering target for magnetic materials 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.

[0016] (7) A sputtering target assembly for magnetic materials, comprising: a sputtering target for magnetic materials as described in any one of (1) to (6); and a backing plate joined to the sputtering target for magnetic materials.

[0017] (8) A method for manufacturing a sputtering target for magnetic materials, wherein the sputtering target for magnetic materials has a sputtering region and a non-sputtering region, the method for manufacturing the sputtering target for magnetic materials includes a step of forming a plurality of rounded protrusions on the surface of the non-sputtering region, the plurality of protrusions including protrusions connected by a connecting portion and / or protrusions not connected by a connecting portion.

[0018] Invention Effects According to embodiments of the present invention, a sputtering target for magnetic materials, a sputtering target assembly for magnetic materials, and a method for manufacturing a sputtering target for magnetic materials can be provided, which can effectively suppress the peeling of redeposited films. Attached Figure Description

[0019] Figure 1 middle, Figure 1 (A) and Figure 1 (B) are schematic top views of a sputtering target formed in a disk shape.

[0020] Figure 2 These are SEM images of the non-sputtered area surfaces used to illustrate the first protrusion, the second protrusion, and the connecting portion.

[0021] Figure 3 middle, Figure 3 (A) and Figure 3 (B) are schematic diagrams of an example of a structure including a first protrusion, a second protrusion, and a connecting portion.

[0022] Figure 4 middle, Figure 4 (A) and Figure 4 (B) are schematic diagrams of an example of a structure including a first protrusion, a second protrusion, a third protrusion, and a connecting portion.

[0023] Figure 5 middle, Figure 5 (A) and Figure 5 (B) is a schematic diagram of an example of a structure including a first protrusion, a second protrusion, a third protrusion, a fourth protrusion, and a connecting portion.

[0024] Figure 6 These are SEM images of the non-sputtered area surfaces used to illustrate the first and second protrusions.

[0025] Figure 7 This is a schematic diagram of an example of the first and second convex portions.

[0026] Figure 8 middle, Figure 8 (A) is a SEM image of the non-sputtered area surface of Example 1. Figure 8(B) is a SEM image of the non-sputtered area surface of Example 2. Figure 8 (C) is a SEM image of the non-sputtered area surface of Example 3. Figure 8 (D) is a SEM image of the non-sputtered area surface of Example 4. Figure 8 (E) is a SEM image of the non-sputtered area surface of Example 5.

[0027] Figure 9 (A) is a photograph of the appearance of the sample surface after spray painting in Example 3. Figure 9 (B) is a photograph of the appearance of the sample surface after cutting out a 1mm square grid in Example 3. Figure 9 (C) is a photograph of the appearance of the sample surface after the peel test in Example 3. Detailed Implementation

[0028] Next, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments; it should be understood that appropriate design changes and modifications can be made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0029] <Sputtering Targets for Magnetic Materials> The shape of the sputtering target for magnetic materials, as an embodiment of the present invention, is not particularly limited and can be flat (including disk-shaped, rectangular plate-shaped), cylindrical, or any other shape. It should be noted that in this specification, the sputtering target for magnetic materials is sometimes simply referred to as a sputtering target.

[0030] The sputtering target of this embodiment is used, for example, for the fabrication of magnetized recording layers and thin films in HDDs. The material of the sputtering target in this embodiment is not particularly limited, and may contain 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 contain 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. Furthermore, the sputtering target material may be a material containing an alloy particle phase and a non-magnetic material. The non-magnetic material may be selected from one or more of carbon, oxides, nitrides, and carbides.

[0031] The sputtering target of the embodiments of the present invention mainly has a surface, a back surface, and a side surface. The surface is roughened as described later. Therefore, the surface has sputtering regions and non-sputtering regions. The sputtering regions are the areas on the surface of the sputtering target sputtered by bombarding accelerated argon ions, and the non-sputtering regions are the areas on the surface of the sputtering target other than the sputtering regions. These non-sputtering regions are areas where a portion of the sputtered particles reattaches to form a redeposited film. In order to effectively suppress the peeling of the redeposited film, a very characteristic roughening treatment is performed in the sputtering target of the embodiments of the present invention.

[0032] Specific examples of the sputtering region and non-sputtering region of the sputtering target according to embodiments of the present invention are shown below. Figure 1 (A) and Figure 1 (B) Figure 1 (A) and Figure 1 (B) are schematic top views of sputtering targets 10a and 10b, which are formed in the shape of a disc.

[0033] At once Figure 1 Regarding the sputtering target 10a of (A), the peripheral portion of the surface of the sputtering target 10a, which is only used for the formation of a redeposition film, is designated as a non-sputtering region 12a, while the other regions, including the central portion, are designated as sputtering regions 11a. The non-sputtering regions 12a at the periphery are 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 non-sputtering regions 12a at the periphery is not particularly limited as long as it at least covers the area where the redeposition film is formed. Furthermore, the sputtering target 10a may also be configured to have not only the peripheral portion of the surface roughened as described above, but also the entire surface or a portion of the side surface roughened as well. In this case, the entire surface or a portion of the side surface of the non-sputtering region has the same characteristics as the non-sputtering regions described later.

[0034] Figure 1In (B), the peripheral portion of the surface of the sputtering target 10b for which a redeposition film is formed is designated as a non-sputtering region 12b, and the central portion of the surface is also designated as a non-sputtering region 13b. The areas outside these non-sputtering regions 12b and 13b are designated as sputtering regions 11b. The peripheral non-sputtering regions 12b are preferably formed with a uniform width of a predetermined size along the circumferential direction of the surface of the sputtering target 10b. The area ratio of the central non-sputtering region 13b and the peripheral non-sputtering regions 12b is not particularly limited as long as it at least covers the area for which the redeposition film is formed. Furthermore, for the sputtering target 10b, it is also possible that only the central portion of its surface is roughened. Additionally, for the sputtering target 10b, it is also possible to have non-sputtering regions where not only the peripheral and central portions of the surface are roughened as described above, but also the entire surface or a portion of the side surface is roughened. In this case, the entire surface or a portion of the side surface has the same characteristics as the non-sputtering regions described later.

[0035] The surface of the non-sputtering region of the sputtering target in an embodiment of the present invention has a plurality of rounded protrusions, including protrusions connected via connecting portions and / or protrusions not connected by connecting portions. With this configuration, a good unevenness is formed on the surface of the non-sputtering region, ensuring surface area. Therefore, the adhesion of the redeposited film formed in the non-sputtering region is improved, and peeling of the redeposited film can be effectively suppressed. As a result, particle contamination during sputtering is suppressed, and the yield is improved. The plurality of protrusions and connecting portions are described in detail below using the accompanying drawings.

[0036] Figure 2In this example, as an embodiment of the sputtering target of the present invention, an SEM image (magnification: 100x) of the surface of the non-sputtering region of the sputtering target of Embodiment 1 described later is shown. Here, a first protrusion and a second protrusion are described as multiple protrusions, but there are multiple protrusions in addition to these. The surface of the non-sputtering region has a rounded first protrusion 21 and a rounded second protrusion 22, which are connected by a connecting portion 23. A plurality of structures are formed on the surface of the non-sputtering region, the structures including the first protrusion 21, the second protrusion 22, and the connecting portion 23. The structure including the first protrusion 21, the second protrusion 22, and the connecting portion 23 is formed by laser processing the surface of the sputtering target as described later, and is a structure in which the first protrusion 21, the second protrusion 22, and the connecting portion 23 are continuous with each other. The plurality of structures, including the first protrusion 21, the second protrusion 22, and the connecting portion 23, can exist individually, or the plurality of structures can be adjacent to each other, or parts of the structures can overlap each other, or they can be a combination thereof. The shape of the first protrusion 21 can be the same as or different from the shape of the second protrusion 22. The structures can be formed on a portion of the surface of the non-sputtering region. Furthermore, if the plurality of structures are formed on the entire surface of the non-sputtering region by partially overlapping each other, the surface area of ​​the non-sputtering region is further increased, and the adhesion of the redeposited film formed in the non-sputtering region is further improved, which is therefore preferred.

[0037] The first protrusion 21 and the second protrusion 22 each have a rounded shape. The first protrusion 21 and the second protrusion 22 can have a rounded shape like a sphere, or a rounded shape like an ellipsoid or a slender ellipsoid (long ellipsoid), or other rounded shapes, and further, they can have a shape with multiple rounded shapes by combining multiple spherical bodies.

[0038] The shape and size of the connecting part 23 are not particularly limited as long as it has a shape that connects the first protrusion 21 and the second protrusion 22. It can be a shape that extends with uniform thickness or a shape that extends with uneven thickness. It can extend in a straight line or in a curved line. It can extend in two or three strands or more.

[0039] A schematic diagram showing an example of a structure including a first protrusion 21, a second protrusion 22, and a connecting portion 23, when observing the surface of the non-sputtering region of a sputtering target according to an embodiment of the present invention, is shown below. Figure 3 (A) and Figure 3 (B). In Figure 3 In (A), the first protrusion 21 and the second protrusion 22 have the same shape. Figure 3In (B), the first protrusion 21 and the second protrusion 22 have different shapes or different sizes. Figure 3 (A) and Figure 3 In (B), the structure including the first protrusion 21, the second protrusion 22 and the connecting portion 23 has a rounded shape such as spherical or ellipsoidal. The first protrusion 21 and the second protrusion 22 are respectively integrally formed with the end of the connecting portion 23.

[0040] The surface of the non-sputtering region of the sputtering target in an embodiment of the present invention may further have a third protrusion. Figure 4 (A) and Figure 4 In (B), a schematic diagram of an example of a structure including a first protrusion 21, a second protrusion 22, a third protrusion 24, and a connecting portion 23 is shown when observing the surface of a non-sputtered area. Figure 4 (A) and Figure 4 In (B), the structure including the first protrusion 21, the second protrusion 22, the third protrusion 24 and the connecting part 23 has a rounded shape such as spherical or ellipsoidal. The first protrusion 21, the second protrusion 22 and the third protrusion 24 are integrally formed with the end of the connecting part 23. Figure 4 The connecting part 23 of (A) is a single piece, having a shape in which a first protrusion 21 is integrally formed at one end and a second protrusion 22 and a third protrusion 24 are integrally formed at the other end. Figure 4 The connecting portion 23 of (B) branches off from the middle and has a total of three ends, each having a shape in which a first protrusion 21, a second protrusion 22 and a third protrusion 24 are integrally formed at each end.

[0041] The surface of the non-sputtering region of the sputtering target in embodiments of the present invention may further have a fourth protrusion. Figure 5 (A) and Figure 5 In (B), a schematic diagram of an example of a structure including a first protrusion 21, a second protrusion 22, a third protrusion 24, a fourth protrusion 25, and a connecting portion 23 is shown when observing the surface of a non-sputtered area. Figure 5 (A) and Figure 5 In (B), the structure including the first protrusion 21, the second protrusion 22, the third protrusion 24, the fourth protrusion 25 and the connecting part 23 has a spherical or ellipsoidal shape, etc. The first protrusion 21, the second protrusion 22, the third protrusion 24 and the fourth protrusion 25 are respectively integrally formed with the end of the connecting part 23. Figure 5 (A) Connector 23 is a single piece, having a shape in which a first protrusion 21 and a fourth protrusion 25 are integrally formed at one end, and a second protrusion 22 and a third protrusion 24 are integrally formed at the other end. Figure 5The connecting portion 23 of (B) branches off from the middle and has a total of four ends, each having a shape in which a first protrusion 21, a second protrusion 22, a third protrusion 24, and a fourth protrusion 25 are integrally formed at each end. Furthermore, it is not limited to... Figure 3 (A) ~ Figure 5 As shown in (B), the structure can also have a fifth protrusion, a sixth protrusion, and so on, as well as more protrusions. With this configuration, various irregularities are formed on the surface of the non-sputtering region, further increasing the surface area. Therefore, the adhesion of the redeposited film formed in the non-sputtering region is further improved, and the peeling of the redeposited film can be further effectively suppressed.

[0042] The size of the first protrusion 21, the second protrusion 22, and other protrusions is not particularly limited, but their longest diameter is preferably 10 μm or more, more preferably 30 μm or more. Furthermore, the size of the first protrusion 21, the second protrusion 22, and other protrusions is typically 10 to 100 μm. The longest diameter of the first protrusion 21, the second protrusion 22, and other protrusions can be determined by observing the non-sputtered area at 100x magnification using a scanning electron microscope (Hitachi High-Tech S-3700N). The longest diameter can be defined as the length of the protrusion along the longest straight line passing through the protrusion on the acquired SEM image, where a straight line is drawn through the protrusion. It should be noted that when measuring with a scanning electron microscope, the accelerating voltage, current value (irradiation current value), brightness, and contrast can be adjusted to ensure clear image observation.

[0043] The distance between the first protrusion 21 and the second protrusion 22, and the distance between the protrusions themselves, are not particularly limited. Typically, they can be 10–100 μm or 20–80 μm. The distance between the protrusions can also be measured using SEM images, similar to the method used for measuring the protrusion size. The distance between the protrusions can be defined as the length of the straight line connecting the centers of the circumcircle of each protrusion on the acquired SEM image.

[0044] Figure 6 In this paper, as another example of a sputtering target according to an embodiment of the present invention, an SEM image (magnification: 100x) of the surface of the non-sputtering region of the sputtering target of Embodiment 5 described later is shown. The surface of the non-sputtering region has a rounded first protrusion 21 and a rounded second protrusion 22, the first protrusion 21 and the second protrusion 22 are not connected by a connecting portion, and the shape of the first protrusion 21 is different from the shape of the second protrusion 22. A plurality of structures are formed on the surface of the non-sputtering region, the structures including such first protrusions 21 and second protrusions 22. These protrusions and Figure 2The illustrated implementation differs in that the protrusions are not connected to each other by connecting portions, but exist independently on the surface of the non-sputtering region. Furthermore, on the surface of the non-sputtering region, the protrusions may exist independently, or they may be configured as a mixture of individually existing protrusions and structures formed by protrusions connected by connecting portions. With this configuration, the surface area of ​​the non-sputtering region increases, and the adhesion of the redeposited film formed in the non-sputtering region is improved.

[0045] for Figure 6 The example shown is a schematic diagram of an example of the first protrusion 21 and the second protrusion 22 when observing the surface of the non-sputtered area. Figure 7 .like Figure 7 As shown, the first rounded protrusion 21 is adjacent to the second rounded protrusion 22. The first protrusion 21 and the second protrusion 22 are not connected by a connecting part. The shape of the first protrusion 21 is different from the shape of the second protrusion 22.

[0046] The size of the separately existing first protrusion 21 and second protrusion 22 is not particularly limited, but the longest diameter of each is preferably 10 μm or more, more preferably 30 μm or more. Furthermore, the size of the separately existing first protrusion 21 and second protrusion 22 is typically 10 to 100 μm. Moreover, the distance between the separately existing first protrusion 21 and second protrusion 22 is not particularly limited, and for adjacent protrusions, it can typically be 10 to 100 μm, or 20 to 80 μm.

[0047] The surface area ratio Sdr of the non-sputtered region 12a is preferably 4.5 or higher. The surface area ratio Sdr represents how much the surface area of ​​a defined region increases relative to the area of ​​the defined region; for example, the surface area ratio Sdr for a completely flat surface is 0. When the surface area ratio Sdr of the non-sputtered region 12a is 4.5 or higher, the roughness of the non-sputtered region 12a is further improved, thereby increasing the contact area with the redeposited film and improving the adhesion of the redeposited film. The surface area ratio Sdr of the non-sputtered region 12a is more preferably 5.0 or higher. There is no particular upper limit to the surface area ratio Sdr of the non-sputtered region 12a; it can be 10.0 or lower, or 9.0 or lower. The surface area ratio Sdr of the non-sputtered region 12a can be measured using a laser microscope according to ISO-25178.

[0048] The surface roughness Sa of the non-sputtering region 12a is preferably 10–40 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 improved, which can improve the adhesion of the redeposited film. When the surface roughness Sa of the non-sputtering region 12a exceeds 40 μm, it means that there are too many protrusions as parts protruding in a direction away from the surface of the sputtering target. Due to the increase in protrusions, arc discharge may be induced. The surface roughness Sa of the non-sputtering region 12a is more preferably 15–35 μm, and even more preferably 18–33 μm. The surface roughness Sa of the non-sputtering region 12a can be measured using a laser microscope according to ISO-25178. In addition, the surface roughness Sa is evaluated by "surface" rather than by "line" to evaluate the average surface roughness Ra. In the average roughness Ra, the measurement result will vary depending on which part is set as the measurement object. For example, when Ra is measured by setting the test object along a specified area, Ra is smaller compared to when Ra is measured by setting the test object across the specified area. Therefore, by using surface roughness Sa, the non-uniformity of Sa caused by the setting position of the test object is reduced, thus improving the accuracy of surface shape control of the sputtering target. As a result, the quality stability of the sputtering target can be improved.

[0049] The maximum height Sz of the non-sputtering region 12a is preferably 100–250 μm. When the maximum height Sz of the non-sputtering region 12a is 100 μm or more, the height difference of the non-sputtering region 12a becomes larger. When a redeposited film is formed in the non-sputtering region 12a, the high and low positions of the non-sputtering region 12a easily ensure the redeposited film. Therefore, the redeposited film becomes less likely to peel off from the non-sputtering region. When the maximum height Sz of the non-sputtering region 12a exceeds 250 μm, it means that the possibility of very large protrusions increases. Therefore, it may become a major factor inducing arc discharge during sputtering. The maximum height Sz of the non-sputtering region 12a is more preferably 110–210 μm, and even more preferably 120–200 μm. The maximum height Sz of the non-sputtering region 12a can be measured using a laser microscope according to ISO-25178.

[0050] The root mean square height Sq of the non-sputtered region 12a is preferably 3 to 45 μm. Sq represents the standard deviation of surface roughness; therefore, a smaller Sq indicates lower surface roughness. Thus, the root mean square height Sq of the non-sputtered region 12a is preferably 3 μm or more. When the root mean square height Sq of the non-sputtered region 12a is less than 45 μm, it indicates a small standard deviation of surface roughness, meaning uniform surface texture, which is advantageous in preventing arc discharge. When the root mean square height Sq of the non-sputtered region 12a exceeds 45 μm, it indicates significant surface height unevenness, making it prone to abnormally high positions. Therefore, the possibility of arc discharge increases. 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 according to ISO-25178.

[0051] It should be noted that Sdr, Sa, Sz, and Sq mentioned above can be measured using a laser microscope (Keyence VK-X3000, head model VK-X3100). The order is shown below.

[0052] With the VK-X3000, a 10x objective lens was used, and measurements were performed at 1.5x digital zoom and 24x image magnification, resulting in a 360x (10x × 1.5x × 24x) image. It should be noted that laser confocal microscopy was selected as the measurement method. For analysis software, the VK-X3000's bundled multi-file analysis application ver. 3.3.1.85 was used.

[0053] First, as the measurement mode, surface roughness measurement is selected, along with the desired roughness parameter and area. When selecting the area, a range of (896 μm × 672 μm) is specified using the acquired image (360x magnification). It should be noted that this area is determined using a laser microscope. Next, the filter settings are set as follows, and analysis is performed. When setting surface shape correction, "plane tilt correction" is used. It should be noted that "plane tilt correction" is also used when the non-sputtering area of ​​either the surface or side of the sputtering target is selected as the measurement object.

[0054] <Filter Settings> Filter type: Gaussian.

[0055] S-filter: None.

[0056] F - Operation: Valid.

[0057] L-filter: None.

[0058] Terminal effect correction: Check the box.

[0059] It should be noted that the surface area is measured using the volumetric area meter function, and the measurement is performed under the following conditions.

[0060] <Surface Area Measurement Conditions> Measurement mode: Convex.

[0061] Height threshold setting: This setting includes the entire concavity and convexity of the measurement field of view. Select the height threshold setting button, which is one of the operation screens of the Keyence VK-X3000, and drag the bar on the switched interface to the top to cover the entire black-displayed graph. This allows you to set the entire concavity and convexity of the measurement field of view to be included in the measurement.

[0062] Minor bumps and dips are ignored: None.

[0063] Ignoring tiny areas: Effective.

[0064] The surface area calculation includes both the upper and lower surfaces: none.

[0065] Regarding the composition of the non-sputtering region mentioned above, for Figure 1 The non-sputtering region 12a of the sputtering target 10a shown in (A) is illustrated, but is not limited thereto. Figure 1 The non-sputtering regions 12b and 13b of the sputtering target 10b shown in (B) may also have the above configuration, and the non-sputtering regions of the sputtering targets in other embodiments of the present invention may also have the above configuration.

[0066] <Sputtering Target Assembly> The sputtering target of the embodiments of the present invention can also be joined with a backing plate as needed to form a sputtering target assembly. The sputtering target assembly can be mounted on a sputtering apparatus for use. Indium or indium tin can be used as the solder. It should be noted that the sputtering target of the embodiments of the present invention can also be mounted on the sputtering apparatus in its original state without using a backing plate. The material of the backing plate is not particularly limited, and examples include Cu, Ti, Mo, and alloys containing at least one of them (e.g., Cu-Ni-Si alloys (e.g., C18000), CuZn alloys, CuCr alloys, etc.). The material of the backing plate preferably has high thermal conductivity; from this viewpoint, Cu is preferred.

[0067] <Manufacturing Method of Sputtering Target> The following describes in detail the manufacturing method of the sputtering target according to an embodiment of the present invention. As a method for manufacturing the sputtering target according to an embodiment of the present invention, firstly, raw materials constituting the sintered body are prepared. The raw materials for the sintered body can be powders 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 they can be powders 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. Furthermore, the raw materials for the sintered body can also be powders containing alloy particle phases and non-magnetic materials. The purity of these raw materials is generally 2N (99% by mass) or higher, preferably 3N (99.9% by mass) or higher, and more preferably 4N (99.99% by mass) or higher. When the purity is below 2N, the sintered body will contain a large number of impurities, which may lead to problems such as undesirable physical properties (e.g., reduced transmittance of the formed film, increased resistivity, and particle generation accompanied by arc discharge). These raw materials can be appropriately prepared according to the desired composition and purity of the sintered body.

[0068] Next, the raw material powders are pulverized and mixed. The pulverization and mixing of the raw material powders can be performed using a ball mill that uses ceramic balls.

[0069] Next, the mixture is mixed and pulverized as described above to obtain a mixture, which is then hot-pressed to obtain a sintered body. The sintering conditions can be appropriately selected based on the composition of the sintered body.

[0070] Next, the sintered body is machined using a lathe to obtain a target of the specified shape. It should be noted that, in order not to affect the laser processing, the surface roughness Ra after lathe machining is preferably set to less than 1 μm.

[0071] Next, under atmospheric pressure, a surface is formed in the non-sputtered area of ​​the sintered body by laser processing. The surface has a first rounded convex portion and a second rounded convex portion, which are connected by a connecting portion or are not connected by a connecting portion, and the shape of the first convex portion is different from the shape of the second convex portion.

[0072] Furthermore, in the non-sputtering region of the sintered body, the shape, size, number, and surface properties (Sdr, Sa, Sz, Sq) of the first protrusion, second protrusion, and connecting portion can be appropriately adjusted by the laser irradiation output, laser scanning speed, and multiple scans of the same area. More specifically, by appropriately adjusting the conditions under the following laser processing conditions, the shape, size, number, and surface properties (Sdr, Sa, Sz, Sq) of the first protrusion, second protrusion, and connecting portion in the non-sputtering region of the sputtering target according to the embodiment of the present invention can be controlled to a desired configuration.

[0073] It should be noted that in this embodiment, no additional heating device is used to heat the sintered body during the roughening process (laser irradiation). This is because, since the roughening process is performed under atmospheric pressure, heating would easily cause oxidation of the sputtering target. Furthermore, in particular, it is not assumed that a process to remove residual stress from the sputtering target is performed before, during, or after the roughening process. Additionally, the back surface of the sputtering target is not roughened. This is because roughening the back surface might reduce the strength of the sputtering target.

[0074] (Laser processing conditions) • Laser processing output: 15~25W.

[0075] • Scanning speed: 150~1000mm / s.

[0076] • Number of scans for the same area: 1 to 10.

[0077] • Frequency: 140~400kHz.

[0078] • Scanning interval: 0.05~0.18mm.

[0079] Furthermore, laser processing can be based on the above conditions, firstly drawing a cross pattern (set to an angle of 0°) with a laser as "layer 1", and then, as "layer 2", drawing a cross pattern with no rotation (0° rotation) or rotation by a specified angle with a laser, thereby drawing a straight line pattern at 0° or every specified angle. In addition, laser processing can be performed a desired number of times.

[0080] The sputtering target of the embodiments of the present invention can be manufactured as described above. Basically, the above conditions depend on the target composition (due to differences in thermal conductivity and melting point), so it is necessary to repeatedly try and experiment with the said composition to find the conditions.

[0081] It should be noted that in this embodiment, it is not assumed that the non-sputtered region will be further roughened by other methods after roughening treatment. For example, physical roughening methods such as bead spraying and chemical roughening methods such as chemical etching are not assumed. This is because, for example, if the non-sputtered region is further bead sprayed after roughening treatment, the blasting medium will remain. It should be noted that as long as the target surface state can be achieved, it is not limited to laser irradiation, and other methods can be used to roughen the non-sputtered region. However, by roughening the non-sputtered region by laser irradiation, a surface of the non-sputtered region 12a without ZrO2 and SiC can be achieved. The presence of ZrO2 and SiC on the surface of the non-sputtered region 12a means, for example, that the elements of the blasting medium are present on the surface of the non-sputtered region 12a. By making the surface of the non-sputtered region 12a free of ZrO2 and SiC, it is possible to prevent the elements of the blasting medium from mixing into the thin film and to suppress arc discharge during sputtering. Furthermore, when the sputtering target does not contain Al2O3, Al2O3 is absent. Although the sputtering target does not contain Al2O3, the presence of Al2O3 on the surface of the non-sputtering region 12a refers to the presence of elements from the blasting medium on the surface of the non-sputtering region 12a. By ensuring that the surface of the non-sputtering region 12a is free of Al2O3, it is possible to prevent elements from the blasting medium from being incorporated into the thin film and to suppress arc discharge during sputtering.

[0082] <Film formation method using sputtering target> Using the sputtering target according to embodiments of the present invention, thin films constituting magnetic recording media can be formed. Specifically, using a sputtering apparatus, accelerated argon ions are used to sputter the surface of the sputtering target, causing particles (sputtered particles) to be released from the sputtering target and deposited on the surface of a substrate pre-positioned at opposite locations, thereby forming a thin film on the surface of the substrate. The sputtering conditions can be appropriately set according to the desired film thickness, composition, etc.

[0083] A portion of the sputtered particles re-attaches to the non-sputtered area of ​​the sputtering target to form a redeposited film. In embodiments of the present invention, the surface of the non-sputtered area of ​​the sputtering target has multiple rounded protrusions, including protrusions connected by connecting portions and / or protrusions not connected by connecting portions. Therefore, the adhesion of the redeposited film formed in the non-sputtered area is improved, and peeling of the redeposited film is effectively suppressed.

[0084] Example The following are embodiments of the present invention, but these embodiments are provided to better understand the invention and its advantages and are not intended to limit the invention.

[0085] <Examples 1-7> • Manufacturing of sputtering targets The sputtering targets of Examples 1 to 7 were manufactured using the following manufacturing methods.

[0086] First, the raw materials constituting the sintered body were prepared. The raw materials used were powders containing Co, Cr, Pt, B, O, Ti, and Si (Examples 1-5), 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 these raw materials was 3N (99.9% by mass).

[0087] Next, the powdered raw materials were pulverized and mixed using a ball mill with beads to obtain a mixture, which was then hot-pressed to obtain a sintered body.

[0088] Next, the sintered body was machined using a lathe to obtain a disc-shaped target.

[0089] Next, under atmospheric pressure, a surface is formed by laser processing of the non-sputtered area of ​​the sintered body. This surface has a first rounded convex portion and a second rounded convex portion, wherein the first and second convex portions are connected by a connecting portion or are not connected by a connecting portion, and the shapes of the first and second convex portions are different. Regarding the laser processing, as "layer 1", a cross pattern (set to an angle of 0°) is first drawn with a laser. Then, as "layer 2", a cross pattern without rotation (0° rotation) or rotated by 45° is drawn by laser overlapping, thereby drawing straight line patterns at 0° or every 45°. It should be noted that, in Embodiment 4, only layer 1 is laser processed.

[0090] The laser processing conditions for layers 1 and 2 are shown below. Furthermore, tables 1 and 2 show the laser processing conditions for each embodiment.

[0091] (Laser processing conditions for layer 1) • Laser processing output: 20W.

[0092] • Scanning speed: 200~400mm / s.

[0093] • Number of scans for the same area: 1.

[0094] • Frequency: 140~220kHz.

[0095] • Scanning interval: 0.1mm.

[0096] (Laser processing conditions for layer 2) • Laser processing output: 20W.

[0097] • Scanning speed: 200~800mm / s.

[0098] • Number of scans for the same area: 1.

[0099] • Frequency: 140~220kHz.

[0100] • Scanning interval: 0.1~0.131mm.

[0101] •SEM photos Regarding the non-sputtered areas of Examples 1 to 7, SEM images were obtained using a Hitachi High-Tech S-3700N. Based on the obtained SEM images, it was confirmed that in each of the non-sputtered areas of Examples 1 to 7, the surface of the non-sputtered area has multiple rounded protrusions, including protrusions connected by connecting portions and / or protrusions not connected by connecting portions.

[0102] Figure 8 (A) ~ Figure 8 SEM images (magnification: 100x) of Examples 1-5 are shown in (E). Acquisition Figure 8 When taking SEM images, the accelerating voltage was set to 15kV and the current value (irradiation current value) was set to 84000nA.

[0103] •Sdr, Sa, Sz, Sq For the sputtering targets of Examples 1-7, the unfolded area ratio Sdr, surface roughness Sa, maximum height Sz, and root mean square height Sq of the non-sputtering region were measured using a laser microscope (Keyence VK-X3000, head model VK-X3100). The measurement sequence was as described above.

[0104] • Peel test For Examples 1-5, a peel test was performed to confirm the adhesion of the redeposited film. The peel test was conducted according to JIS-K5400 (checkerboard tape method). Commercially available lacquer spray was applied to each non-splashed area and allowed to dry for at least 6 hours. Then, slits were cut into the coating film formed by applying the spray paint using a cutter to create 100 square grids of 1 mm each. Transparent tape was then adhered to the surface of the coating film with the slits, and the peel strength of the checkerboard pattern was evaluated according to a score of 0 to 10 as specified in JIS-K5400 when peeling off the transparent tape.

[0105] In all sputtering targets of Examples 1 to 5, each cut was fine and smooth on both sides, and no peeling was observed at the intersection of the cuts and at each grid of the square, so it was rated as 10 points.

[0106] Based on these results, it was confirmed that Examples 1-5 effectively suppressed the peeling of the redeposited film. It should be noted that, as an example of the peeling test method, Figure 9 Photograph (A) shows an observation of the surface appearance of the sample after spray painting in Example 3. Figure 9 Photograph (B) shows an observation of the surface appearance of the sample after cutting out a 1mm square grid in Example 3. Figure 9 Photographs showing the appearance of the sample surface after the peel test in Example 3 are shown in (C).

[0107] The evaluation results are shown in Table 2. <Inspection> In Examples 1-5, the sputtering targets all have multiple rounded protrusions on the surface of the non-sputtering region. These protrusions have shapes including protrusions connected by connecting portions and / or protrusions not connected by connecting portions. Therefore, a good unevenness is formed on the surface of the non-sputtering region, ensuring surface area and improving the adhesion of the redeposited film formed in the non-sputtering region, thus effectively suppressing the peeling of the redeposited film. Furthermore, regarding Examples 6 and 7, similarly to Examples 1-5, the surface of the non-sputtering region has multiple rounded protrusions. These protrusions have shapes including protrusions connected by connecting portions and / or protrusions not connected by connecting portions. Therefore, it is believed that they can also effectively suppress the peeling of the redeposited film.

[0108] Explanation of reference numerals in the attached figures 10a, 10b: Sputtering target; 11a, 11b: Sputtering area; 12a, 12b, 13b: Non-sputtering area; 21: First protrusion; 22: Second protrusion; 23: Connecting part; 24: Third protrusion; 25: Fourth protrusion.

Claims

1. A sputtering target for magnetic materials, wherein, It has a sputtering area and a non-sputtering area. The surface of the non-sputtered area has multiple rounded protrusions. The plurality of protrusions includes protrusions connected via connecting portions and / or protrusions not connected by connecting portions.

2. The sputtering target for magnetic materials according to claim 1, wherein, The unfolded area ratio of the surface of the non-sputtered region is 4.5 or higher than Sdr.

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

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

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

6. The sputtering target for magnetic materials according to claim 1 or 2, wherein, The sputtering target for the magnetic material comprises 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 magnetic materials, wherein, have: The sputtering target for magnetic materials as described in claim 1 or 2; and The backing plate is bonded to the magnetic material using a sputtering target.

8. A method for manufacturing a sputtering target for magnetic materials, wherein, The sputtering target for the magnetic material has a sputtering region and a non-sputtering region. The method for manufacturing the magnetic material sputtering target includes a step of forming a plurality of rounded protrusions on the surface of the non-sputtering region. The plurality of protrusions includes protrusions connected via connecting portions and / or protrusions not connected by connecting portions.

Images