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

Abstract

To provide a sputtering target for a magnetic material capable of satisfactory suppressing a peeling of a re-deposited film, an assembly of the sputtering target for the magnetic material, and a manufacturing method of the sputtering target for the magnetic material.SOLUTION: A sputtering target for a magnetic material has a sputtering region and a non-sputtering region. A surface of the non-sputtering region has multiple concave parts with a roundness, the multiple concave parts including the concave parts connected via a connection part and / or the concave parts not connected via the connection part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sputtering target for a magnetic material, an assembled product of a sputtering target 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 a film of an HDD.

Background Art

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

[0003] Sputtering is a technique in which the surface of a sputtering target serving as a sputtering source is sputtered by accelerated argon ions, particles (sputter particles) are released from the sputtering target, and the sputter particles are deposited on the surface of a substrate arranged in a position facing in advance, thereby forming a thin film on the surface of the substrate.

[0004] Some of the sputter particles may reattach to a predetermined location on the sputtering target to form a laminate (also called a redeposition film). When this redeposition film peels off from the sputtering target, it causes problems such as an increase in particles during sputtering, which is the cause of arcing (abnormal discharge) during sputtering, and contamination of the thin film, resulting in a decrease in the product yield.

[0005] In response to such problems, Patent Document 1 discloses that the region where the redeposition film of the sputtering target is formed is surface roughened by blasting using glass beads. Further, it is disclosed that peeling of the redeposition film from the roughened surface can thereby be suppressed. Patent Document 2 also discloses that roughening treatment is performed on the sputtering target. Further, Patent Document 2 discloses that the region where the roughening treatment is performed is within the range from the outer periphery (0%) of the sputtering target to the position 2 to 13% in the central direction, and / or within the range from the center (0%) to the position 12 to 33% in the outer peripheral direction.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] In both Patent Documents 1 and 2, only controlling the arithmetic mean roughness Ra is described, and there is room for improvement from the viewpoint of suppressing redeposition film peeling.

[0008] Therefore, an embodiment of the present invention aims to provide a sputtering target for magnetic materials, an assembled product of a sputtering target for magnetic materials, and a method for manufacturing a sputtering target for magnetic materials that can satisfactorily suppress redeposition film peeling.

Means for Solving the Problems

[0009] The above problems are solved by the present invention specified as follows. (1) A sputtering target for magnetic materials having a sputtering region and a non-sputtering region, The surface of the non-sputtering region has a plurality of rounded convex portions, The plurality of convex portions include convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion, a sputtering target for a magnetic material. (2) The sputtering target for a magnetic material according to (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 (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 any one of (1) to (3), 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 any one of (1) to (4), 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 any one of (1) to (5), 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 any one of (1) to (6), 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, comprising a step of forming a plurality of rounded convex portions on the surface of the non-sputtering region, wherein the plurality of convex portions include convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion, a method for manufacturing a sputtering target for a magnetic material. [Effect of the Invention]

[0010] According to an embodiment of the present invention, it is possible to provide a sputtering target for a magnetic material, an assembled product of a sputtering target for a magnetic material, and a method for manufacturing a sputtering target for a magnetic material, which can favorably suppress peeling of the ridepo film.

Brief Description of Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying out the Invention

[0012] Next, embodiments for carrying out 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 design changes, improvements, etc. can be appropriately made based on the ordinary knowledge of those skilled in the art without departing from the gist of the present invention.

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

[0014] The sputtering target according to this embodiment is used, for example, for the magnetization recording layer and thin film formation of HDDs. The material of the sputtering target according to the embodiments of the present invention is not particularly limited, but the composition 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. Further, the material of the sputtering target may be a material containing an alloy particle phase and a non-magnetic material. Examples of the non-magnetic material include one or more selected from carbon, oxides, nitrides, and carbides.

[0015] The sputtering target according to an embodiment of the present invention mainly has a front surface, a back surface, and side surfaces. The front surface is subjected to a roughening treatment described later. Therefore, the front surface has a sputtering region and a non-sputtering region. The sputtering region is a region on the front surface of the sputtering target where accelerated argon ions are collided to cause sputtering, and the non-sputtering region is a region other than the sputtering region on the front surface of the sputtering target. This non-sputtering region is a region where a part of the sputtered particles re-deposits to form a re-deposition film, and a very characteristic roughening treatment is performed on the sputtering target according to an embodiment of the present invention in order to favorably suppress peeling of the re-deposition film.

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

[0017] In the sputtering target 10a of FIG. 1(A), only the peripheral portion of the front surface of the sputtering target 10a where the re-deposition film is formed is the non-sputtering region 12a, and the other regions including the central portion are the sputtering region 11a. The non-sputtering region 12a at the peripheral portion is preferably formed with a uniform width of a predetermined size along the circumferential direction of the front surface of the sputtering target 10a. The area ratio of the non-sputtering region 12a at the peripheral portion is not particularly limited as long as it covers at least the position where the re-deposition film is formed. Further, the sputtering target 10a may constitute a non-sputtering region in which not only the peripheral portion of the front surface as described above but also the entire surface or a part of the side surface is subjected to a roughening treatment. Also in that case, the entire surface or a part of the non-sputtering region on the side surface has the same characteristics as the non-sputtering region described later.

[0018] The sputtering target 10b in FIG. 1(B) has a non-sputtering region 12b at the peripheral edge of the surface of the sputtering target 10b where the redeposition film is formed, and a non-sputtering region 13b also at the central portion of the surface. The region other than these non-sputtering regions 12b and 13b is the sputtering region 11b. The non-sputtering region 12b at the peripheral edge 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 non-sputtering region 13b at the central portion and the non-sputtering region 12b at the peripheral edge are not particularly limited as long as at least the position where the redeposition film is formed is covered. Also, only the central portion of the surface of the sputtering target 10b may be roughened. Further, the sputtering target 10b may constitute a non-sputtering region where not only the peripheral edge and the central portion of the surface as described above but also the entire or a part of the side surface is roughened. Even in that case, the non-sputtering region of the entire or a part of the side surface has the same characteristics as the non-sputtering region described later.

[0019] The surface of the non-sputtering region of the sputtering target according to the embodiment of the present invention has a plurality of rounded convex portions. The plurality of convex portions include convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion. According to such a configuration, good unevenness can be formed on the surface of the non-sputtering region, and the surface area can be ensured. For this reason, the adhesion of the redeposition film formed in the non-sputtering region is improved, and peeling of the redeposition film can be favorably suppressed. As a result, the mixing of particles during sputtering is suppressed, and the production rate can be improved. In the present invention, the "rounded" convex portion on the surface of the non-sputtering region indicates a convex portion having a curved surface that is not pointed at the end and bulges roundly. The plurality of convex portions and the connecting portion will be described in detail below with reference to the drawings.

[0020] Figure 2 shows, as an example of a sputtering target according to an embodiment of the present invention, a SEM photograph (magnification: 100 times) of the surface of the non-sputtering region of the sputtering target according to Example 1 described later. In addition, the 11 scales in the lower right shown in the SEM photographs of Figure 2 and Figures 6, 9(A) to (E) described later are provided at 50 μm intervals, indicating that the distance from the first scale to the last scale is 500 μm. Here, the first convex portion and the second convex portion will be described as a plurality of convex portions, but there are also a plurality of 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 such a first convex portion 21, a second convex portion 22, and a connecting portion 23 are formed on the surface of the non-sputtering region. The structure including the first convex portion 21, the second convex portion 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 convex portion 21, the second convex portion 22, and the connecting portion 23 are continuous with each other. The plurality of structures including the first convex portion 21, the second convex portion 22, and the connecting portion 23 may exist alone, a plurality of them may be adjacent to each other, a part of the structures may 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 structure may be formed on a part of the surface of the non-sputtering region. Further, when a plurality of structures are formed while partially overlapping each other over the entire surface of the non-sputtering region, the surface area of the surface of the non-sputtering region is further increased, and the adhesion of the re-deposition film formed in the non-sputtering region is further improved, which is preferable.

[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, may have a rounded shape like an ellipsoid or an elongated ellipsoid (prolate ellipsoid), may have other rounded shapes, or may have a rounded shape formed by combining a plurality of spherical bodies.

[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. It may have a shape that extends with a uniform thickness, or a shape that extends with a non-uniform thickness. It may extend linearly, curvilinearly, bifurcate into two or three branches and extend, or branch further and extend.

[0023] Figs. 3(A) and 3(B) show schematic views of an example of the structure including the first convex portion 21, the second convex portion 22, and the connecting portion 23 when observing the surface of the non-sputtering region of the sputtering target according to the embodiment of the present invention. In Fig. 3(A), the first convex portion 21 and the second convex portion 22 have the same shape respectively, and in Fig. 3(B), the first convex portion 21 and the second convex portion 22 have different shapes or different sizes respectively. In Figs. 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 having a rounded shape such as a spherical shape or an elliptical shape are integrally formed at the ends of the connecting portion 23 respectively.

[0024] The surface of the non-sputtering region of the sputtering target according to the embodiment of the present invention may further have a third convex portion. Figs. 4(A) and 4(B) show schematic views of an example of the structure including the first convex portion 21, the second convex portion 22, the third convex portion 24, and the connecting portion 23 when observing the surface of the non-sputtering region. In Figs. 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 having a rounded shape such as a spherical shape or an elliptical shape are integrally formed at the ends of the connecting portion 23 respectively. Fig. 4(A) has a shape in which the connecting portion 23 is single, the first convex portion 21 is integrally formed at one end thereof, and the second convex portion 22 and the third convex portion 24 are integrally formed at the other end. Fig. 4(B) has a shape in which the connecting portion 23 branches from the middle and has 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 respectively.

[0025] The surface of the non-sputtering region of the sputtering target according to the embodiment of the present invention may further have a fourth convex portion. FIGS. 5(A) and 5(B) show a schematic diagram of 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 when observing the surface of the non-sputtering region. In FIGS. 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 having a rounded shape such as a spherical shape or an elliptical shape are integrally formed at the ends of the connecting portion 23, respectively. FIG. 5(A) has a shape in which the connecting portion 23 is single, the first convex portion 21 and the fourth convex portion 25 are integrally formed at one end thereof, and the second convex portion 22 and the third convex portion 24 are integrally formed at the other end thereof. FIG. 5(B) has a shape in which the connecting portion 23 branches in the middle and has a total of four ends, and the first convex portion 21, the second convex portion 22, the third convex portion 24, and the fourth convex portion 25 are integrally formed at each end thereof. Further, not limited to the shapes shown in FIGS. 3(A) to 5(B), the structure may have more convex portions such as a fifth convex portion and a sixth convex portion. According to such a configuration, various kinds of irregularities are formed on the surface of the non-sputtering region, and the surface area is further increased. Therefore, the adhesion of the redeposition film formed in the non-sputtering region is further improved, and it is possible to more favorably suppress the peeling of the redeposition film.

[0026] The sizes of the convex portions such as the first convex portion 21 and the second convex portion 22 are not particularly limited, but preferably each has a maximum diameter of 10 μm or more, and more preferably 30 μm or more. Further, the sizes of the convex portions such as the first convex portion 21 and the second convex portion 22 are typically 10 to 100 μm. The maximum 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-sputtering region at a magnification of 100 times with a scanning electron microscope (S-3700N manufactured by Hitachi High-Tech). The maximum diameter can be defined as the length on the convex portion in the straight line having the longest length passing through the convex portion when a straight line is drawn on the convex portion in the acquired SEM photograph. When measuring with a scanning electron microscope, the acceleration voltage, the current value (irradiation current value), the brightness, and the contrast can be adjusted so that the image can be clearly seen.

[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. Regarding the distance between the convex portions as well, similar to the size of the convex portions described above, it can be measured by obtaining an SEM photograph. The distance between the convex portions can be defined as the length of a straight line connecting the centers of the circumscribed circles of the respective convex portions on the obtained SEM photograph.

[0028] FIG. 6 shows, as another example of the sputtering target according to the embodiment of the present invention, an SEM photograph (magnification: 100 times) of the surface of the non-sputtering region of the sputtering target according to Example 5 described later. 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 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. On the surface of the non-sputtering region, a plurality of structures including such first convex portions 21 and second convex portions 22 are formed. Unlike the embodiment shown in FIG. 2, these convex portions are not connected to each other by a connecting portion and exist alone on the surface of the non-sputtering region. Further, on the surface of the non-sputtering region, those in which the convex portions exist alone, or a configuration may be adopted in which the convex portions existing alone and a structure in which the convex portions are connected by a connecting portion are mixed. According to such a configuration, the surface area of the surface of the non-sputtering region increases, and the adhesion of the redeposition film formed in the non-sputtering region is improved.

[0029] FIG. 7 shows 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-sputtering region in 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 first convex portion 21 and the second convex portion 22 that exist independently are not particularly limited, but preferably each has a major axis length of 10 μm or more, and more preferably 30 μm or more. Further, the sizes of the first convex portion 21 and the second convex portion 22 that exist independently are typically 10 to 100 μm. Also, the distance between the first convex portion 21 and the second convex portion 22 that exist independently is not particularly limited, but in the case of adjacent convex portions, it may typically be 10 to 100 μm, or may be 20 to 80 μm.

[0031] The developed area ratio Sdr of the surface of the non-sputtering region 12a is preferably 4.5 or more. The developed area ratio Sdr represents how much the developed area (surface area) of a predetermined region has increased with respect to the area of the predetermined region. For example, the developed area ratio Sdr of a completely flat surface is 0. When the developed area ratio Sdr of the surface of the non-sputtering region 12a is 4.5 or more, the roughness of the non-sputtering region 12a is further increased, whereby the contact area with the re-deposition film is increased, and the adhesion of the re-deposition film can be improved. More preferably, the developed area ratio Sdr of the surface of the non-sputtering region 12a is 5.0 or more. The upper limit of the developed area ratio Sdr of the surface of the non-sputtering region 12a is not particularly limited, but it may be 10.0 or less, or may be 9.0 or less. The developed area ratio Sdr of the surface of the non-sputtering 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, and the adhesion of the re-deposition film can be improved. When the surface roughness Sa of the non-sputtering region 12a exceeds 40 μm, it means that there are too many protruding portions which are the portions protruding in the direction away from the surface of the sputtering target. An increase in the 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. Also, while the average surface roughness Ra is evaluated by "line", the surface roughness Sa is evaluated by "surface". In the case of the average roughness Ra, the measurement result varies depending on which part is set as the measurement target. For example, when Ra is measured by setting the measurement target along a predetermined region, Ra is smaller than when Ra is measured by setting the measurement target across the predetermined region. Therefore, by using the surface roughness Sa, the variation of Sa due to the setting position of the measurement target is reduced, so that the accuracy of controlling the surface shape of the sputtering target is improved. As a result, the quality stability of the sputtering target can be improved.

[0033] The maximum height Sz of the non-sputtering region 12a is preferably 100 to 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 large, and when the re-deposition film is formed on the non-sputtering region 12a, it becomes easier to secure the re-deposition film at the high and low positions of the non-sputtering region 12a. Therefore, the re-deposition film is 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 there is a high possibility of the existence of very large convex portions. Therefore, there is a risk of inducing arcing during sputtering. The maximum height Sz of the non-sputtering region 12a is more preferably 110 to 210 μm, and even more preferably 120 to 200 μm. The maximum height Sz of the non-sputtering region 12a can be measured using a laser microscope in accordance with ISO-25178.

[0034] The root mean square height Sq of the non-sputtering region 12a is preferably 3 to 45 μm. Since Sq has the meaning of the standard deviation of roughness, a small Sq indicates that the roughness itself is small. Therefore, it is preferable that the root mean square height Sq of the non-sputtering region 12a is 3 μm or more. When the root mean square height Sq of the non-sputtering region 12a is 45 μm or less, it indicates that the standard deviation of the surface roughness is small, which means that the unevenness is uniform, and it is advantageous in preventing arcing. When the root mean square height Sq of the non-sputtering region 12a exceeds 45 μm, it indicates that the height variation of the surface is large, so that a particularly high position is likely to exist. For this reason, the possibility of arcing occurring increases. The root mean square height Sq of the non-sputtering 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-sputtering region 12a can be measured using a laser microscope in accordance with ISO-25178.

[0035] Note that the above Sdr, Sa, Sz, and Sq can be measured by a laser microscope (Keyence VK-X3000, head type VK-X3100). The procedure is shown below. In the case of the VK-X3000, with an objective lens of 10x magnification, digital zoom of 1.5x, and a screen magnification of 24x, an image of 360x (10x × 1.5x × 24x) can be obtained by measurement. The measurement method selected is laser confocal. The multi-file analysis application ver. 3.3.1.85 included with the VK-X3000 is used as the analysis software. First, as the measurement mode, select surface roughness measurement and choose the desired roughness parameters and area. When selecting the area, specify a range of (896 μm × 672 μm) from the acquired image (360x image). This range specification operation is performed with a laser microscope, and the above-mentioned area is thus determined. Next, set the filter settings as follows and perform the analysis. When setting the surface shape correction, use "plane tilt correction". Note that "plane tilt correction" is used regardless of whether it is a non-sputtered area on the surface or side of the sputtering target that is the measurement object. <Filter settings> Filter type: Gaussian S-filter: None F-operation: Enabled L-filter: None Correction for end effect: Checked Note that the surface area is measured under the following conditions using the function of volume area measurement. <Surface area measurement conditions> Measurement mode: Convex part Setting the height threshold: Set it so that all unevenness in the measurement field of view is included in the measurement. By selecting the height threshold setting button in Figure 8(A), which is one of the operation screens of the Keyence VK-X3000, the screen in Figure 8(B) is displayed. Drag the bar on that screen upward so that it covers all the spectra shown in black, and thus it can be set so that all unevenness in the measurement field of view is included in the measurement. Ignore minute unevenness: None (Do not check the "Ignore minute unevenness" checkbox in Figure 8(A)) Ignore minute areas: Enabled (Check the "Ignore minute areas" checkbox in Figure 8(A)) Calculation of surface area does not include top and bottom surfaces (do not check the "Calculation of surface area includes top and bottom surfaces" checkbox in Fig. 8(A))

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

[0037] <Sputtering target assembly> The sputtering target according to an embodiment of the present invention may be joined to a backing plate as needed to form a sputtering target assembly. The sputtering target assembly can be mounted on a sputtering apparatus for use. As the brazing material, indium or indium tin can be used. Note that the sputtering target according to an embodiment of the present invention may be directly mounted on the sputtering apparatus 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 these (e.g., Cu-Ni-Si alloy (e.g., C18000, etc.), CuZn alloy, CuCr alloy). The material of the backing plate preferably has high thermal conductivity, and from this viewpoint, Cu is suitable.

[0038] <Method for manufacturing sputtering target> Hereinafter, the method for manufacturing a sputtering target according to an embodiment of the present invention will be described in detail. As the method for manufacturing a sputtering target according to an embodiment of the present invention, first, raw materials constituting the 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 ceramics 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. Further, the raw material of the sintered body may be a powder containing an alloy particle phase and a non-magnetic material. The purity of these raw materials is usually 2N (99% by mass) or more, preferably 3N (99.9% by mass) or more, and more preferably 4N (99.99% by mass) or more. If the purity is lower than 2N, the sintered body will contain many impurities, resulting in problems such as the inability to obtain desired physical properties (for example, a decrease in the transmittance of the formed thin film, an increase in the resistance value, and the generation of particles due to arcing). These raw materials can be appropriately prepared from the desired composition and purity of the sintered body.

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

[0040] Next, a sintered body is obtained by hot-pressing the mixture obtained by mixing and pulverizing as described above. The sintering conditions can be appropriately selected according to the composition of the sintered body.

[0041] Next, the sintered body is processed by a lathe to obtain a target having a predetermined shape. Note that the surface roughness Ra after lathe processing is preferably 1 μm or less so as not to affect the laser processing.

[0042] Next, under atmospheric pressure, in the non-sputtering region of the sintered body, by laser processing, there are provided a rounded first convex portion and a rounded second convex portion, and the first convex portion and the second convex portion are connected via a connecting portion, or the first convex portion and the second convex portion are not connected via a connecting portion, and the shape of the first convex portion is different from that of the second convex portion to form a surface.

[0043] Also, in the non-sputtering region of the sintered body, the shape, size, number, Sdr, Sa, Sz, and Sq of the surface of the first convex portion, the second convex portion, and the connecting portion can be appropriately adjusted by the output of laser irradiation, the scanning speed of the laser beam, and multiple scans at the same location, etc. More specifically, by appropriately adjusting each condition under the following laser processing conditions, the shape, size, number, Sdr, Sa, Sz, and Sq of the surface of the first convex portion, the second convex portion, and the 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.

[0044] In this embodiment, during the roughening process (during laser irradiation), the sintered body is not heated using another heating device. This is because when heating under atmospheric pressure, oxidation of the sputtering target is likely to progress. Also, particularly, before and after the roughening process, or during the roughening process, it is not assumed that a process for removing the residual stress of the sputtering target is performed. Also, the back surface of the sputtering target is not roughened. This is because if the roughening process is performed on the back surface as well, the strength of the sputtering target may decrease.

[0045] (Laser processing conditions) · Output of laser processing: 15 - 25 W · Scanning speed: 150 - 1000 mm / s · Number of scans at the same location: 1 - 10 times · Frequency: 140 - 400 kHz · Scanning pitch: 0.05 - 0.18 mm · Wavelength: 1064 nm · Spot diameter: 80 μm · Power density: 298567 - 497611 W / cm 2 Further, based on the above conditions, in the case of "Layer 1", a cross pattern may be first drawn with a laser (at an angle of 0°), and then, as "Layer 2", a cross pattern that is not rotated (0° rotation) or rotated by a predetermined angle may be overlapped and drawn with a laser to draw a linear pattern every 0° or predetermined angle. Further, the laser processing may be performed a desired number of times. As described above, the sputtering target according to the embodiment of the present invention can be manufactured. However, basically, since the above conditions 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 in the relevant composition.

[0046] In addition, in the present embodiment, it is not assumed that the non-sputtering region is roughened further by another method after the roughening process of the non-sputtering region. For example, physically roughening means such as bead blasting and chemically roughening means such as chemical etching are not assumed. For example, if the non-sputtering region is bead blasted after the roughening process of the non-sputtering region, the blasting media will remain. Note that as long as the target surface state can be achieved, the roughening process of the non-sputtering region may be performed by other means, not limited to laser irradiation. However, by roughening the non-sputtering region by laser irradiation, the surface of the non-sputtering region 12a where ZrO2 and SiC do not exist can be realized. The presence of ZrO2 and SiC on the surface of the non-sputtering region 12a means, for example, that the elements of the blasting media are present on the surface of the non-sputtering region 12a. By the non-existence of ZrO2 and SiC on the surface of the non-sputtering region 12a, the mixing of the elements of the blasting media into the thin film can be prevented, and the arcing during sputtering can be suppressed. Also, when the composition of the sputtering target does not contain Al2O3, Al2O3 does not exist. Despite the fact that the composition of the sputtering target does not contain Al2O3, the presence of Al2O3 on the surface of the non-sputtering region 12a means, for example, that the elements of the blasting media are present on the surface of the non-sputtering region 12a. By the non-existence of Al2O3 on the surface of the non-sputtering region 12a, the mixing of the elements of the blasting media into the thin film can be prevented, and the arcing during sputtering can be suppressed.

[0047] <Film formation method using a sputtering target> Using the sputtering target according to the embodiment of the present invention, a thin film constituting a magnetic recording medium can be mainly formed. Specifically, the surface of the sputtering target is sputtered by accelerated argon ions using a sputtering apparatus, particles (sputtered particles) are released from the sputtering target, and the sputtered particles are deposited on the surface of a substrate disposed in a position facing in advance, so that a thin film can be formed on the surface of the substrate. The sputtering conditions can be appropriately set according to the desired film thickness, composition, and the like.

[0048] A part of the sputtered particles reattaches to the non-sputtering region of the sputtering target to form a re-deposition film. The sputtering target according to the embodiment of the present invention has 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. Therefore, the adhesion of the re-deposition film formed in the non-sputtering region is improved, and the peeling of the re-deposition film is preferably suppressed.

Example

[0049] Examples of the present invention are shown below. These examples are provided to better understand the present invention and its advantages, and are not intended to limit the invention.

[0050] <Examples 1 to 7> ·Manufacture of sputtering target The sputtering targets according to Examples 1 to 7 were respectively manufactured by the following manufacturing method. First, raw materials constituting the sintered body were prepared. As the raw materials of the sintered body, powders containing Co, Cr, Pt, B, O, Ti, Si (Examples 1 to 5), powders containing Co, Pt, B, O, Ti, Si (Example 6), and powders containing Co, Pt, Ru, Ti, O, Si (Example 7) were used. The purity of these raw materials was 3N (99.9% by mass) respectively. Next, the powders of these raw materials were pulverized by a ball mill using beads, and the obtained mixture was hot-pressed to obtain a sintered body. Next, the sintered body was processed by a lathe to obtain a disk-shaped target. Next, under atmospheric pressure, in the non-sputtering region of the sintered body, by laser processing, a surface was formed that had a rounded first convex portion and a rounded second convex portion, and the first convex portion and the second convex portion were connected via a connecting portion, or the first convex portion and the second convex portion were not connected via a connecting portion, and the shape of the first convex portion was different from the shape of the second convex portion. For the laser processing, as "Layer 1", first a cross pattern was drawn with a laser (at an angle of 0°), and then, as "Layer 2", without rotation (0° rotation), or by overlapping and drawing a cross pattern rotated by 45° with a laser, a linear pattern was drawn every 0° or 45°. Note that for Example 4, only the laser processing of Layer 1 was performed. The laser processing conditions for each of Layer 1 and Layer 2 are shown below. Also, the laser processing conditions in each example are shown in Tables 1 and 2.

[0051] (Laser processing conditions for Layer 1) · Output of laser processing: 20 W · Scanning speed: 200 - 400 mm / s · Number of scans at the same location: 1 time · Frequency: 140 - 220 kHz · Scanning pitch: 0.1 mm · Wavelength: 1064 nm · Spot diameter: 80 μm · Power density: 398089 W / cm 2

[0052] (Laser processing conditions for Layer 2) · Output of laser processing: 20 W · Scanning speed: 200 - 800 mm / s · Number of scans at the same location: 1 time · Frequency: 140 - 220 kHz · Scanning pitch: 0.1 - 0.131 mm · Wavelength: 1064 nm · Spot diameter: 80 μm · Power density: 398089 W / cm 2

[0053] ·SEM photograph SEM photographs of the non-sputtering regions of Examples 1 to 7 were obtained using an S-3700N manufactured by Hitachi High-Tech. From the obtained SEM photographs, it was confirmed that the surface of the non-sputtering region of each of Examples 1 to 7 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. FIGS. 9(A) to 9(E) show SEM photographs (magnification: 100 times) according to Examples 1 to 5, respectively. When obtaining the SEM photographs in FIG. 9, the acceleration voltage was set to 15 kV and the current value (irradiation current value) was set to 84000 nA, respectively.

[0054] ·Sdr, Sa, Sz, Sq For the sputtering targets of Examples 1 to 7, the developed 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 unit type VK-X3100). The measurement procedure is as described above.

[0055] ·Peel test For Examples 1 to 5, a peel test was carried out to confirm the adhesion of the re-deposited film. The peel test was carried out in accordance with JIS-K5400 (cross-cut tape method). A commercially available lacquer spray was applied to each non-sputtering region and left for 6 hours or more for drying. Thereafter, cuts were made in the coating film formed by applying the lacquer spray with a cutter to create 100 1 mm square grids (square meshes). Further, cellophane tape was attached to the surface of the cut coating film, and when the cellophane tape was peeled off, the degree of cross-cut peeling was evaluated on a scale of 0 to 10 points specified in JIS-K5400. Since 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 and each square mesh, they were evaluated as 10 points. From these results, it was confirmed that Examples 1 to 5 were able to suppress the peeling of the redeposition film well. As an example of the peeling test method, FIG. 10(A) shows a photograph of the appearance of the sample surface after the lacquer spray coating in Example 3, FIG. 10(B) shows a photograph of the appearance of the sample surface after cutting out a 1 mm square grid in Example 3, and FIG. 10(C) shows a photograph of the appearance of the sample surface after the peeling test in Example 3. The evaluation results are shown in Table 2.

[0056]

Table 1

[0057]

Table 2

[0058] <Discussion> The sputtering targets of Examples 1 to 5 all had a surface in the non-sputtering region with a plurality of rounded convex portions, and the plurality of convex portions had a shape including convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion. Therefore, it was possible to form good irregularities on the surface of the non-sputtering region and secure the surface area, improving the adhesion of the redeposition film formed in the non-sputtering region and enabling good suppression of the peeling of the redeposition film. Also, for 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 a connecting portion and / or convex portions not connected via a connecting portion. Therefore, it is considered that the peeling of the redeposition film can be similarly well suppressed.

Explanation of Signs

[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 part 24 Third convex part 25 Fourth convex part

Claims

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 convex portions, the plurality of convex portions include convex portions connected via a connecting portion and / or convex portions not connected via a connecting portion, a sputtering target for magnetic materials.

2. The sputtering target for magnetic materials 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 magnetic materials 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 magnetic materials 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 magnetic materials 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 magnetic materials 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 magnetic materials, comprising the sputtering target for magnetic materials according to claim 1 or 2, and a backing plate joined to the sputtering target for magnetic materials.

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

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