Sputtering target

Abstract

To provide a sputtering target from which a target material is less likely to be detached.SOLUTION: A sputtering target includes: a backing plate; and a target material joined to a joint region of the backing plate via a joint material. A joint area of a joint part between the target material and the backing plate is 97% or more relative to an area of the joint region. A maximum defect area of the part where the joint material does not exist between the target material and the backing plate is 0.6% or less relative to an area of the joint region.SELECTED DRAWING: Figure 1C

Description

[Technical Field]

[0001] The present invention relates to a sputtering target. [Background technology]

[0002] An example of a conventional method for joining sputtering targets is that described in Japanese Patent Laid-Open No. 6-114549 (Patent Document 1). In this sputtering target joining method, a molten brazing filler metal coating is formed on each of the target material and the backing plate, and the target material and the backing plate are moved relative to each other while being rubbed together to overlap, thereby squeezing out oxides that have formed on the coating surface and combining the brazing filler metal coatings in a state where no oxides or air bubbles are trapped inside, and then the brazing filler metal is cooled and solidified to complete the brazing process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-114549 Summary of the Invention [Problem to be solved by the invention]

[0004] However, it has been found that the conventional sputtering target bonding method described above does not provide sufficient bonding between the target material and the backing plate, and there is a risk of the target material peeling off during sputtering. As a result of extensive research, the present inventors have noticed that the conventional method has a small ratio (bonding rate) of the actual bonded area (bonding area) to the area of ​​the region where the target material and the backing plate should be bonded (bonding region), and that the area of ​​the largest area (maximum defect area) among the areas where no bonding material is present (unbonded areas) located between the target material and the backing plate is large, and have found that there is a relationship between the bonding rate, the maximum defect area, and peeling off of the target material.

[0005] Therefore, an object of the present invention is to provide a sputtering target that can realize a sputtering target in which the target material is less likely to peel off during sputtering. [Means for solving the problem]

[0006] In order to solve the above problem, one embodiment of the sputtering target comprises: A backing plate; a target material bonded to a bonding region of the backing plate (a region of the backing plate where the target material is to be bonded) via a bonding material; Equipped with the bonding area of ​​the bonded portion (bonded portion) between the target material and the backing plate is 97% or more of the area of ​​the bonding region; The maximum defect area of ​​the unbonded portion between the target material and the backing plate is 0.6% or less of the area of ​​the bonded region.

[0007] According to the embodiment, it is possible to manufacture a sputtering target in which the bonding rate can be improved, the maximum defect area can be reduced, and the target material is less likely to peel off.

[0008] In one embodiment of the sputtering target, the length of the target material is 1000 mm or more and 4000 mm or less.

[0009] According to the embodiment, it is possible to manufacture a sputtering target in which the target material is less likely to peel off even when the sputtering target is long.

[0010] Also, one embodiment of a method for joining a target material and a backing plate includes: A method for bonding a target material and a backing plate with a bonding material, comprising: applying a bonding material to a region (bonding region) on the main surface of the backing plate where the target material is to be bonded; a step of sliding and moving the target material in the first direction along the main surface of the backing plate so that an edge (first edge) of the target material moves from a first edge side of the bonding region of the backing plate to a position beyond a second edge of the bonding region of the backing plate that faces the first edge in a first direction; sliding the target material along the major surface of the backing plate in a second direction opposite to the first direction to align the target material with the bonding area of ​​the backing plate; Equipped with. Hereinafter, moving the target material by sliding it in a first direction will also be referred to as "slide," and moving the target material by sliding it in a second direction will also be referred to as "reverse."

[0011] According to the embodiment, the target material is slid relative to the backing plate in a first direction and then reversed in a second direction to align the target material with the bonding area of ​​the backing plate. This improves the bonding rate when bonding the target material to the backing plate and reduces the size of the maximum defect area, which is the largest area among unbonded areas. Therefore, a sputtering target can be manufactured in which the target material is less likely to peel off.

[0012] In addition, in one embodiment of the method for joining the target material and the backing plate, The target material and the backing plate are formed to be elongated, The edge of the target material is formed along the longitudinal direction of the target material, the first edge and the second edge of the bonding region of the backing plate are formed along the longitudinal direction of the backing plate and are opposed to each other in the lateral direction of the backing plate, The target material is moved relative to the backing plate by sliding it in the lateral direction of the backing plate.

[0013] According to the embodiment, in the case of a long target material and backing plate, the moving distance of the target material relative to the backing plate can be reduced, and the operation time can be shortened.

[0014] In addition, in one embodiment of the method for joining the target material and the backing plate, a step of arranging a plurality of wires on the main surface of the backing plate before the step of applying the bonding material; When the target material moves in the first direction and the second direction, the target material is caused to slide on the wire.

[0015] According to the embodiment, since the target material slides on the wire, the target material can be easily moved while the surface to be joined (joining surface) of the target material and the surface to be joined (joining surface) of the backing plate are kept substantially parallel to each other, thereby improving the joining rate. In addition, since the wire functions as a spacer, the thickness of the joining layer formed by the joining material between the target material and the backing plate can be made constant.

[0016] In one embodiment of the method for joining a target material and a backing plate, the diameter of the wire is 0.05 mm or more and 0.5 mm or less.

[0017] According to the embodiment, wire breakage can be prevented, and unevenness in the thickness of the bonding layer formed by the bonding material can be prevented.

[0018] Furthermore, one embodiment of the method for joining a target material and a backing plate includes a step of replenishing joining material on the first edge side of the joining area of ​​the backing plate between the step of moving the target material in the first direction and the step of moving the target material in the second direction.

[0019] According to the above embodiment, bonding material is replenished on the first edge side of the bonding area of ​​the backing plate, so that bonding material can be replenished on the first edge side of the bonding area where bonding material is likely to run short, thereby further improving the bonding rate and further reducing the maximum defect area.

[0020] Furthermore, in one embodiment of the method for joining a target material and a backing plate, when the edge (first edge) of the target material is moved to a position beyond the second edge of the joining region of the backing plate in the step of moving the target material in the first direction, the distance in the first direction from the second edge of the joining region of the backing plate to the edge (first edge) of the target material is A, and the width of the joining region in the first direction is W, then 0.03≦A / W<1.0.

[0021] According to the embodiment, the moving distance of the target material relative to the backing plate can be reduced, while the bonding rate can be improved and the maximum defect area can be reduced.

[0022] Furthermore, in one embodiment of the method for joining a target material and a backing plate, when the edge (first edge) of the target material is positioned on the first edge side of the joining region of the backing plate in the step of moving the target material in the first direction, if the distance in the first direction from the first edge of the joining region of the backing plate to the edge (first edge) of the target material is B and the width of the joining region in the first direction is W, then 0≦B / W<2.0.

[0023] According to the above embodiment, the moving distance of the target material relative to the backing plate can be reduced, and the target material can be placed on the backing plate and then slid, thereby improving the joining rate and reducing the size of the maximum defect area.

[0024] In one embodiment of the method for manufacturing a sputtering target, the target material and the backing plate are joined together using the joining method to manufacture a sputtering target.

[0025] According to the embodiment, the bonding rate can be improved when bonding the target material to the backing plate, and the size of the maximum defect area, which is the largest area among unbonded portions, can be reduced, thereby making it possible to manufacture a sputtering target in which the target material is less likely to peel off. [Effects of the Invention]

[0026] According to the sputtering target of the present invention, it is possible to produce a sputtering target in which the target material is less likely to peel off. [Brief explanation of the drawings]

[0027] [Figure 1A] 1A and 1B are explanatory views showing an embodiment of a method for joining a target material and a backing plate according to the present invention. [Figure 1B] 1A and 1B are explanatory views showing an embodiment of a method for joining a target material and a backing plate according to the present invention. [Figure 1C] 1A and 1B are explanatory views showing an embodiment of a method for joining a target material and a backing plate according to the present invention. [Figure 1D] 1A and 1B are explanatory views showing an embodiment of a method for joining a target material and a backing plate according to the present invention. [Figure 1E] 1A and 1B are explanatory views showing an embodiment of a method for joining a target material and a backing plate according to the present invention. [Figure 2A] FIG. 10 is a simplified cross-sectional view showing a state in which no bonding material is present in the bonding layer present between the target material and the backing plate. [Figure 2B] FIG. 10 is a simplified cross-sectional view showing a state in which no bonding material is present in the bonding layer present between the target material and the backing plate. [Figure 3A] FIG. 2 is a simplified diagram showing the state of a bonding material between a target material and a backing plate of the sputtering target of the present invention. [Figure 3B] FIG. 10 is a simplified diagram showing the state of a bonding material between a target material and a backing plate of a sputtering target of a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention will be described in detail below with reference to the illustrated embodiments.

[0029] (Embodiment) 1A to 1E are explanatory diagrams showing one embodiment of a method for bonding a target material and a backing plate (hereinafter referred to as the "bonding method") of the present invention. As shown in Fig. 1A to 1E, this method bonds a target material 2 and a backing plate 3 with a bonding material 4.

[0030] As shown in FIG. 1A, a target material 2 and a backing plate 3 are prepared. The target material 2 is formed in the shape of a long plate. The length of the long side of the target material 2 is, for example, 1000 mm to 4000 mm, preferably 1500 mm to 3500 mm, more preferably 2000 mm to 3200 mm, and even more preferably 2200 mm to 3000 mm. The length of the short side of the target material 2 is, for example, 100 mm to 2000 mm, preferably 120 mm to 1000 mm, more preferably 130 mm to 500 mm, and even more preferably 150 mm to 300 mm. The length of the long side and the length of the short side may be the same or different. The thickness of the target material 2 is, for example, 5 mm to 40 mm, preferably 10 mm to 30 mm, and more preferably 12 mm to 25 mm. In the present invention, even when a target material for a large flat panel display is used, it is possible to improve the bonding rate and reduce the maximum defect area.

[0031] The aspect ratio of the length in the long side direction to the length in the short side direction of the sputtering target (length in the long side direction / length in the short side direction) is from 1 to 30, preferably from 5 to 25, more preferably from 6 to 20, even more preferably from 7 to 18, and particularly preferably from 8 to 15. This makes the sputtering target long and thin, but it makes it easier to achieve the effects of the reverse process, and it is possible to produce a sputtering target with a high bonding rate and a small maximum defect area.

[0032] The target material 2 has a sputtering surface 2a on its upper surface. When viewed from the top, the target material 2 has a first edge 21 and a second edge 22 corresponding to the long sides. The first edge 21 and the second edge 22 are formed along the longitudinal direction of the target material 2, and the first edge 21 and the second edge 22 are arranged facing each other in the lateral direction of the target material 2.

[0033] The target material 2 has a surface (bonding surface) to be bonded to the backing plate on the back side of the sputtering surface 2a, which is the upper surface. The size of the bonding surface is usually substantially the same as the size of the target material 2, but may be smaller than the area of ​​the target material 2 (length in the long side direction x length in the short side direction, area in a plan view if there is a rounded portion) due to the removal of burrs that occur on the bonding surface during machining and the removal of corners that can cause abnormal discharge. The area of ​​the bonding surface may usually be 95% or more, preferably 98% or more, and more preferably 99% or more of the area of ​​the target material 2.

[0034] During sputtering of the target material 2, an inert gas ionized by sputtering collides with the sputtering surface 2a. Target atoms contained in the target material 2 are ejected from the sputtering surface 2a that is impacted by the ionized inert gas. The ejected atoms are deposited on a substrate placed opposite the sputtering surface 2a, forming a thin film on the substrate.

[0035] The material from which the target material 2 is made is not particularly limited as long as it is made of a material composed of a ceramic or sintered body, such as a metal, alloy, oxide, or nitride, that is typically used in film formation by sputtering. An appropriate target material may be selected depending on the application and purpose. For example, the target material 2 can be made from a material selected from the group consisting of metals such as aluminum, copper, chromium, iron, tantalum, titanium, zirconium, tungsten, molybdenum, niobium, indium, silver, cobalt, ruthenium, platinum, palladium, and nickel, and alloys thereof, as well as tin-doped indium oxide (ITO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and In-Ga-Zn composite oxide (IGZO). However, the material constituting the target material 2 is not limited to these. For example, Al or an Al alloy is preferred as the material for the target material 2 for electrodes or wiring materials, and it is particularly preferred to use Al with a purity of 99.99% or higher, more preferably 99.999% or higher, or an Al alloy (Al-Cu, Al-Si, Al-Cu-Si) using Al as a base material. High-purity Al has a relatively large linear thermal expansion coefficient, so it is prone to warping due to the heat it receives during sputtering, and peeling from the backing plate is likely to occur. However, according to the present invention, the bonding rate can be improved, the maximum defect area can be reduced, and peeling from the backing plate can be prevented.

[0036] The backing plate 3 is formed in a long plate shape. The length of the backing plate 3 in the long side direction is, for example, 1000 mm or more and 4500 mm or less, preferably 1500 mm or more and 4000 mm or less, more preferably 2000 mm or more and 3500 mm or less, and even more preferably 2500 mm or more and 3200 mm or less. The length of the backing plate 3 in the short side direction is, for example, 100 mm or more and 2000 mm or less, preferably 150 mm or more and 1200 mm or less, more preferably 180 mm or more and 750 mm or less, and even more preferably 200 mm or more and 350 mm or less. Here, one direction in the short side direction of the backing plate 3 is defined as a first direction D1, and the other direction in the short side direction of the backing plate 3 opposite to the first direction D1 is defined as a second direction D2.

[0037] The backing plate 3 has a bonding area 30 (shown by hatching) on ​​the upper main surface 3a. The bonding area 30 is an area where the target material 2 is to be bonded. The shape of the bonding area 30 corresponds to the shape of the target material 2. In other words, the size of the bonding area 30 is substantially the same as the size of the bonding surface of the target material 2, preferably the size of the target material 2.

[0038] When viewed from above, the bonding region 30 has a first edge 31 and a second edge 32 corresponding to the long sides. The first edge 31 and the second edge 32 are formed along the longitudinal direction of the backing plate 3, and the first edge 31 and the second edge 32 are arranged opposite each other in the lateral direction of the backing plate 3. The second edge 32 is located in the first direction D1 of the first edge 31.

[0039] The backing plate 3 is made of a conductive material, such as a metal or its alloy, etc. Examples of metals include copper, copper alloys, aluminum, aluminum alloys, titanium, and SUS.

[0040] The bonding surface of the target material 2 and the bonding region 30 of the backing plate 3 are preferably flat. From the viewpoint of reducing slippage and the maximum defect area when the target material 2 is slid or reversed, the flatness is 1.0 mm or less, preferably 0.5 mm or less, and more preferably 0.3 mm or less. Flatness is a numerical value indicating the smoothness (uniformity) of a plane, and refers to the degree of deviation from a geometrically correct plane of a planar shape. Furthermore, from the viewpoint of preventing the flow of the bonding material on the bonding region 30 of the backing plate 3 during bonding, the backing plate 3 should have its upper main surface 3a and its back surface approximately parallel, preferably parallel. From the viewpoint of easily applying a constant force to the target material 2 when the target material 2 is slid or reversed, the target material 2 should have its upper sputtering surface 2a and its back surface, which is the bonding surface, approximately parallel, preferably parallel.

[0041] The bonding process is performed while the target material 2, backing plate 3, and bonding material 4 are heated. As shown in FIG. 1B, the bonding material 4 is applied to the entire bonding area 30 of the backing plate 3. The amount of the bonding material 4 to be applied is 1.5×10 -6 kg / mm 2 or more, preferably 2.5 x 10 -6 kg / mm 2 More preferably, 4.5 × 10 -6 kg / mm 2 More preferably, 10 × 10 -6 kg / mm 2 or more, and even more preferably 14×10 -6 kg / mm 2 There is no particular upper limit, but from the viewpoint of workability in the joining process, it is preferably 50 × 10 -6 kg / mm 2 Less than or equal to 35 × 10 -6 kg / mm 2 or less, more preferably 25 × 10 -6 kg / mm 2The bonding material 4 is made of a metal with a low melting point (for example, 723 K or less), such as solder or brazing filler metal, and the solder material is, for example, a metal such as indium, tin, zinc, lead, silver, copper, bismuth, cadmium, or antimony, or an alloy thereof, such as In material, In-Sn material, Sn-Zn material, Sn-Zn-In material, In-Ag material, Sn-Pb-Ag material, Sn-Bi material, Sn-Ag-Cu material, Pb-Sn material, Pb-Ag material, Zn-Cd material, Pb-Sn-Sb material, Pb-Sn-Cd material, Pb-Sn-In material, or Bi-Sn-Sb material, and it is generally preferable to use a solder material with a low melting point, such as In, an In alloy, Sn, or an Sn alloy. The bonding is performed at a temperature equal to or higher than the melting point of the bonding material 4, preferably 140°C or higher, and more preferably 150°C to 300°C. If the viscosity of the molten bonding material 4 is 0.5 mPa·s or higher, preferably 1.0 mPa·s or higher, more preferably 1.5 mPa·s or higher, and 5 mPa·s or lower, preferably 3 mPa·s or lower, and more preferably 2.5 mPa·s or lower, the bonding rate can be improved and the maximum defect area can be reduced. Furthermore, before bonding the target material 2 and the backing plate 3, a pretreatment (metallization treatment) can be performed on the bonding surface of the target material 2 with the backing plate 3 and the bonding surface of the backing plate 3 with the target material 2 to improve wettability with the bonding material 4. Pretreatment can include surface roughening, hairline finishing, texturing, and metallization, such as polishing and grinding. The bonding surfaces of the target material 2 and the backing plate 3 can be provided with textured surfaces, such as polished, ground, hairline, and textured surfaces, or metallized layers. For example, polishing can be performed manually or with a polishing machine equipped with an abrasive, using a paper or fiber substrate coated with abrasive grains. Metallization can be performed by applying a metallization material to the bonding surfaces and then subjecting them to ultrasonic irradiation. The metallization material can be selected from the same materials as the bonding material 4, such as In and Sn-Zn. The thickness of the metallization layer is between 1 μm and 100 μm. This range ensures wettability with the bonding material 4 and improves the bonding rate.The areas of the target material 2 and the backing plate 3 that are not to be joined may be masked in advance with heat-resistant tape to prevent adhesion of the joining material 4 and formation of a metallized layer.

[0042] 1C, the first edge 21 of the target material 2 is then placed on the first edge 31 side of the bonding region 30 of the backing plate 3. At this time, the first edge 21 of the target material 2 is preferably placed so as to overlap the bonding region 30.

[0043] As shown in FIG. 1D, the target material 2 is then slid in a first direction D1 along the main surface 3a of the backing plate 3 so that the first edge 21 of the target material 2 moves from the first edge 31 side of the bonding area 30 of the backing plate 3 to a position beyond the second edge 32 of the bonding area 30 of the backing plate 3.

[0044] 1E, the target material 2 is then slid along the main surface 3a of the backing plate 3 in the second direction D2 until the target material 2 is aligned with the bonding area 30 of the backing plate 3. The target material 2 and the backing plate 3 are then precisely aligned, and the bonded body of the target material 2 and the backing plate 3 is cooled while they are fixed in place by placing a weight or by clamping them with a vice, a vise, or a clamp, and the bonding material 4 is solidified. In this way, the target material 2 and the backing plate 3 are bonded together by the bonding material 4, and a sputtering target 1 is manufactured.

[0045] According to the bonding method, the target material 2 is slid relative to the backing plate 3 in the first direction D1 and then reversed in the second direction D2, thereby aligning the target material 2 with the bonding area 30 of the backing plate 3. In this way, by not only sliding the target material 2 but also reversing it, the bonding material 4 can be pulled back in the second direction D2 by surface tension as the target material 2 is reversed, thereby reducing the space between the target material 2 and the backing plate 3 where the bonding material 4 is not present and making it possible to reduce the size of unbonded areas.

[0046] Therefore, in bonding the target material 2 and the backing plate 3, the bonding rate can be improved and the maximum defect area can be reduced. The bonding ratio refers to the ratio of the bonding area of ​​the bonding portion between the target material 2 and the backing plate 3 to the area of ​​the bonding region 30 . Specifically, the bonding area refers to the total area of ​​the portion where no region without bonding material is detected when viewed from the thickness direction of the bonding layer between the target material 2 and the backing plate 3 . The maximum defect area refers to the largest area of ​​the portions between the target material 2 and the backing plate 3 where the bonding material 4 is not present. Here, the portion where the bonding material 4 is not present (unbonded portion) refers to a region in the thickness direction of the bonding layer where the bonding material is not present, i.e., a space or a portion where a foreign substance other than the bonding material, such as an oxide of the bonding material, is detected. This may include a portion where the bonding material is not present in the entire thickness direction of the bonding layer, as well as a portion where the bonding material is not present. For example, as shown in FIG. 2A, the bonding layer 6 between the target material 2 and the backing plate 3 may have a space S where the bonding material 4 is not present in a portion of the thickness direction of the bonding layer 6 (vertical direction in the figure). Alternatively, as shown in FIG. 2B, the bonding layer 6 between the target material 2 and the backing plate 3 may have a space S where the bonding material 4 is not present throughout the entire thickness direction of the bonding layer 6 (vertical direction in the figure). The region where the bonding material is not present can be detected using the measurement method described below. For example, when using ultrasonic flaw detection, if there is a space where the bonding material is not present in the bonding layer, incident ultrasonic waves are reflected at the interface, allowing the defect to be identified.

[0047] Therefore, according to the present invention, the bonding rate between the target material 2 and the backing plate 3 can be increased and the maximum defect area can be reduced, making it possible to manufacture a sputtering target 1 in which areas with low bonding strength are less likely to be formed and the target material 2 is less likely to peel off.

[0048] As described above, in the present invention, it has been found that by focusing on both the bonding rate and the maximum defect area, the target material 2 is less likely to peel off during sputtering. Specifically, with regard to the bonding rate, as the bonding rate increases, the area where the bonding material 4 is not present can be reduced, and the target material 2 is less likely to peel off.

[0049] On the other hand, with regard to the maximum defect area, if the maximum defect area becomes large, large defects will occur locally, which will deteriorate the electrical and thermal conduction in that area, causing heat to concentrate in that area and melting the bonding material 4, making it easier for the target material 2 to peel off. For this reason, if the maximum defect area becomes small, large defects will not occur locally and the target material 2 will be less likely to peel off.

[0050] Furthermore, according to the joining method, the target material 2 is moved by sliding it relative to the backing plate 3 in the short direction of the backing plate 3. This makes it possible to reduce the moving distance of the target material 2 relative to the backing plate 3 in the case of long target materials 2 and backing plates 3, thereby shortening the working time.

[0051] Preferably, prior to the application of the bonding material 4 (see FIG. 1B), multiple wires 5 are arranged on the main surface 3a of the backing plate 3 as shown in FIG. 1A. The wires 5 are made of, for example, stainless steel or copper. Specifically, the wires 5 are arranged in the bonding region 30 so as to extend in the first direction D1, and the multiple wires 5 are arranged at intervals in a direction perpendicular to the first direction D1. The target material 2 is then moved in the first direction D1 and the second direction D2 by sliding on the wires 5. This allows the target material 2 to slide on the wires 5, making it easy to move. Furthermore, by using the wires 5 as spacers, the thickness of the bonding layer formed by the bonding material 4 can be made constant. The thickness of the bonding layer is typically 0.03 mm to 1.5 mm, preferably 0.05 mm to 1 mm, more preferably 0.08 mm to 0.5 mm, and even more preferably 0.1 mm to 0.35 mm.

[0052] Preferably, the diameter of wire 5 is 0.05 mm or more and 0.5 mm or less, and more preferably 0.1 mm or more and 0.3 mm or less, which makes it difficult for wire 5 to break and reduces variations in the thickness of the bonding layer.

[0053] Preferably, bonding material 4 is replenished on the first edge 31 side of the bonding region 30 of the backing plate 3 between the step of moving the target material 2 in the first direction D1 (see FIG. 1D) and the step of moving the target material 2 in the second direction D2 (see FIG. 1E). Specifically, in the state shown in FIG. 1D, bonding material 4 is added to the portion of the bonding region 30 that is not covered by the target material 2. In this way, since bonding material 4 is replenished on the first edge 31 side of the bonding region 30 of the backing plate 3, bonding material 4 can be replenished on the first edge 31 side of the bonding region 30, where bonding material 4 is likely to become insufficient as the target material 2 moves, thereby further improving the bonding rate and further reducing the maximum defect area. The amount of bonding material 4 to be replenished is preferably 0.5×10 -6 kg / mm 2 or more, more preferably 0.8 × 10 -6 kg / mm 2 or more, more preferably 1.0 × 10 -6 kg / mm 2 There is no particular upper limit, but from the viewpoint of workability in the joining process, it is preferably 20 × 10 -6 kg / mm 2 Less than or equal to 10×10 -6 kg / mm 2 or less, more preferably 7.0 × 10 -6 kg / mm 2 The following is the result.

[0054] 1D , when the first edge 21 of the target material 2 is moved beyond the second edge 32 of the bonding region 30 of the backing plate 3 in the first direction D1, the distance in the first direction D1 from the second edge 32 of the bonding region 30 of the backing plate 3 to the first edge 21 of the target material 2 is defined as A, and the width of the bonding region 30 in the first direction D1 is defined as W. The relationship A / W satisfies 0.03≦A / W<1.0, preferably 0.05≦A / W≦0.8, and more preferably 0.06≦A / W≦0.6. Specifically, the relationship A satisfies 10 mm≦A≦150 mm, preferably 12 mm≦A≦120 mm, and more preferably 150 mm≦W≦300 mm. This arrangement can improve the bonding rate and reduce the maximum defect area while reducing the moving distance of the target material 2 relative to the backing plate 3.

[0055] Preferably, in the step of moving the target material 2 in the first direction D1, as shown in FIG. 1C , when the first edge 21 of the target material 2 is positioned toward the first edge 31 of the bonding region 30 of the backing plate 3, the distance in the first direction D1 from the first edge 31 of the bonding region 30 of the backing plate 3 to the first edge 21 of the target material 2 is B, and the width of the bonding region 30 in the first direction D1 is W. The following relationship holds: 0≦B / W<2.0, preferably 0≦B / W≦1.5, more preferably 0.03≦B / W≦1.2, and even more preferably 0.10≦B / W≦1.0. Specifically, the relationship holds: 0 mm≦B≦300 mm, preferably 5 mm≦B / W≦200 mm, and preferably 150 mm≦W≦300 mm. This allows the moving distance of the target material 2 relative to the backing plate 3 to be reduced, improving the bonding rate and reducing the maximum defect area.

[0056] The speed of the movement (slide) of the target material 2 in the first direction D1 or the movement (reverse) in the second direction D2 is preferably 100 mm / sec or less, more preferably 50 mm / sec or less, and even more preferably 30 mm / sec or less, from the viewpoint of preventing excessive movement or escape of the bonding material placed in the bonding region. The lower limit is not particularly limited, but from the viewpoint of productivity, it is 1 mm / sec or more, preferably 5 mm / sec or more.

[0057] It is preferable to provide a step of applying vibration from the top surface of the target material 2 to remove air that may be present in the bonding layer when the edge of the target material 2 is positioned on the first edge side of the bonding area of ​​the backing plate and / or when the movement (sliding) of the target material 2 in the first direction D1 is completed. The vibration can be applied by lightly tapping the top surface of the target material or by applying vibration in a direction parallel to the top surface of the target material 2. The vibration is preferably applied to the entire bonding layer between the target material and the backing plate (the bonding area where the target material is placed) when the edge of the target material 2 is positioned on the first edge side of the bonding area of ​​the backing plate, and to the leading end of the movement (reverse) in the second direction D2 when the movement (sliding) of the target material 2 in the first direction D1 is completed. The vibration is preferably applied from the center toward the periphery of the bonding layer between the target material and the backing plate (the bonding area where the target material is placed). This allows the air present in the bonding layer to be removed, improving the bonding rate and reducing the maximum defect area. In particular, when the edge of the target material 2 is positioned on the first edge side of the bonding area of ​​the backing plate, there is a high possibility that air will be trapped in the bonding layer (the bonding area on which the target material is placed) between the target material and the backing plate. Therefore, by providing an air removal process, it is possible to further improve the bonding rate and reduce the maximum defect area.

[0058] Next, we will explain the method for manufacturing the sputtering target 1. As described above, the sputtering target is manufactured by joining the target material and the backing plate using the joining method.

[0059] In the manufacturing method of the present invention, the target material can be processed into an approximately plate-like shape, but the method for processing into a plate-like shape is not particularly limited. Target materials made from metallic materials can be produced, for example, by subjecting rectangular, cylindrical, or columnar target materials obtained by melting and casting to plastic processing such as rolling, extrusion, or forging, followed by mechanical processing such as cutting, grinding, or polishing (such as cutting, milling, or end milling) to produce target materials of the desired size and surface condition. Rolling processing is described, for example, in JP 2010-132942 A and WO 2011 / 034127 A. Extrusion processing is described, for example, in JP 2008-156694 A. Forging processes are described, for example, in JP 2017-150015 A, JP 2001-240949 A, or the Aluminum Technology Handbook (edited by the Aluminum Technology Handbook Editorial Committee of the Japan Light Metal Association, Karos Publishing, New Edition, published November 18, 1996). Using the joining method of the present invention, a machined plate-shaped target material is joined to a backing plate to produce a sputtering target. The target material may be purchased and machined to a specified size. Alternatively, the target material may be a sputtering target obtained by removing the backing plate and removing the joining material from a sputtering target that does not meet the product specifications due to an abnormality in the joining with the backing plate during the manufacturing process of the sputtering target 1. If necessary, the surface of the joined sputtering target may be finished by cutting or polishing.

[0060] In the method for producing a sputtering target of the present invention, the joining method of the present invention is used, and therefore a sputtering target of improved quality can be obtained.

[0061] Next, the sputtering target 1 bonded by the above bonding method will be described.

[0062] As shown in FIG. 1E, the sputtering target 1 has a backing plate 3 and a target material 2 bonded to a bonding region 30 of the backing plate 3 via a bonding material 4.

[0063] FIG. 3A is a simplified diagram showing the state of the bonding material 4 between the target material 2 and the backing plate 3 of the sputtering target 1. In FIG. 3A, a defect (unbonded portion) 10 where the bonding material 4 is not present in the bonding region 30 is indicated by hatching. The defect 10 can be measured using, for example, ultrasonic flaw detection or transmission X-ray observation. However, when the bonding region is large, ultrasonic flaw detection is preferable. Examples of ultrasonic flaw detection devices that can be used include the FS LINE and FS LINE Hybrid manufactured by Hitachi Power Solutions Co., Ltd., and the PDS and ADS71000 phased array ultrasonic flaw detection imaging systems manufactured by KJTD Corporation. Furthermore, when determining the bonding ratio or maximum defect area using ultrasonic flaw detection, it is necessary to use a pseudo-defect sample with a flat-bottom hole of a specified size and adjust the ultrasonic flaw detection measurement conditions to recognize the reflected waves from the defect. Because the propagation speed of ultrasonic waves differs depending on the material, it is preferable to make the pseudo-defect sample from the same material as the ultrasonic incident side of the sputtering target 1 to ensure uniform measurement sensitivity and conditions. Furthermore, it is preferable that the distance between the ultrasonic wave incidence surface of the pseudo-defect sample and the bottom surface of the flat-bottomed hole is equal to the distance between the ultrasonic wave incidence surface of the sputtering target 1 and the bonding layer.

[0064] As shown in FIG. 3A, the area of ​​the portion between the target material 2 and the backing plate 3 where no defect locations 10 are detected is 97% or more of the area of ​​the bonding region 30. In other words, the bonding rate is 97% or more, preferably 98% or more, and more preferably 98.5% or more. Furthermore, the maximum defect area of ​​the defect locations 10 in the bonding layer between the target material 2 and the backing plate 3 is 2% or less of the area of ​​the bonding region 30, preferably 1% or less, more preferably 0.6% or less, even more preferably 0.3% or less, still more preferably 0.1% or less, and particularly preferably less than 0.05%. For example, when the area of ​​the bonding region 30 is 200 mm × 2300 mm, the maximum defect area is 2000 mm 2 The following is the result.

[0065] According to the present invention, it is possible to manufacture a sputtering target 1 that can improve the bonding rate and reduce the maximum defect area, and that is less likely to peel off the target material 2. Preferably, the length of the target material 2 is 1000 mm or more and 4000 mm or less, and it is possible to manufacture a sputtering target 1 in which the target material 2 is less likely to peel off even when the sputtering target 1 is long.

[0066] The upper limit of the bonding rate is 100%, but from the viewpoint of making it easy to peel off the target material when removing the backing plate from a sputtering target that has become out of specification due to an abnormality that occurred during bonding or from a sputtering target that has been used in sputtering, the bonding rate is preferably 99.99% or less, more preferably 99.95% or less, and even more preferably 99.90% or less. Note that the target material can be peeled off from the sputtering target by applying heat to the sputtering target to a temperature equal to or higher than the melting point of the bonding material used for bonding, softening or melting the bonding layer, and physically destroying the bonding layer as necessary. The lower limit of the ratio of the maximum defect area to the area of ​​the bonding region 30 is not particularly limited, but from the viewpoint of further suppressing warpage of the sputtering target due to heat generated during sputtering, it is 0.001% or more, preferably 0.003% or more, more preferably 0.005% or more, and even more preferably 0.008% or more. When the lower limit of the maximum defect area ratio is above the above range, deformation of the target material caused by heat during sputtering is mitigated by the local defects, and warpage of the sputtering target is reduced.

[0067] In contrast, FIG. 3B shows a comparative example of a sputtering target 100 in which the target material and the backing plate are bonded together simply by sliding the target material in the first direction D1, illustrating the state of the bond between the target material and the backing plate. As shown in FIG. 3B, compared to FIG. 3A, the proportion of defects 10 is higher, the bonding rate is smaller, and the maximum defect area of ​​defects 10 is larger. Thus, simply sliding the target material results in a poor bond between the target material and the backing plate, which makes the target material more likely to peel off. This tendency is particularly pronounced for sputtering targets with long target materials or large bonded areas.

[0068] In a preferred embodiment of the sputtering target of the present invention, a wire may be provided between the target material and the backing plate, i.e., in the bonding layer. By providing a wire in the bonding layer, it is easier to ensure the thickness of the bonding layer and make the thickness of the bonding layer more uniform, which increases the bonding rate of the sputtering target 1 and reduces the maximum defect area, making it possible to produce a sputtering target 1 in which the target material 2 is less likely to peel off.

[0069] Example 1 A rolled plate made of high-purity aluminum with a purity of 99.999% was prepared, and a target material of 200 mm × 2300 mm × t16 mm was obtained by cutting it using a double-column machining center (the area of ​​the bonding area was 4.5 × 10 5 mm 2 ) was fabricated, and a backing plate made of oxygen-free copper with a purity of 99.99% was prepared. The width W of the bonding region in the first direction D1 during the target material movement process (i.e., the width of the target material) was 200 mm.

[0070] The target material and the backing plate were heated on a hot plate to a temperature equal to or higher than the melting point of the bonding material.

[0071] The Sn-Zn-In alloy material was melted on the bonding surface of the target material, and the In material was melted on the bonding surface of the backing plate, and the bonding surfaces of both materials were metallized using an ultrasonic soldering iron. After the metallization process, oxides of the Sn-Zn-In alloy material and In material, as well as excess Sn-Zn-In alloy material and In material, were removed with a spatula from the bonding surfaces of the target material and the backing plate.

[0072] Ten 0.2 mm diameter SUS wires were placed at approximately equal intervals on the bonding surface of the metallized backing plate in a direction perpendicular to the longitudinal direction of the backing plate, and an In material for bonding was applied to the bonding surface from above the SUS wires. The amount of In material for bonding applied to the bonding surface from above the SUS wires was 7.80 kg.

[0073] The orientation of the target material was changed so that its bonding surface was parallel to and facing the bonding surface of the backing plate, and it was placed on the wire so that one of its long sides overlapped one of the long sides of the backing plate (target material installation position B = 0), and the target material was slid toward the designated bonding position. The ratio A / W of the distance the target material overran from the designated bonding position (overrun amount) to its width W was 0.1625, and the leading end of the target material in the second direction D2 (reverse) of movement was lightly struck from above to expel the air.

[0074] The target material was then slid to the desired joining position, the target material position was finely adjusted so that the target material was in the desired joining position, a weight was placed on the target material to fix the target material and the backing plate, and the joined body was then cooled to produce a sputtering target.

[0075] After the In material solidified, the warp caused by the difference in the linear expansion coefficient between the target material and the backing plate was corrected to obtain the target. The bonding rate and maximum defect area were measured using the ultrasonic flaw detector FS-LINE manufactured by Hitachi Power Solutions Co., Ltd.

[0076] The bonding rate and maximum defect area were measured using the following procedure. First, a rolled plate made of high-purity aluminum with a purity of 99.999% was used. Both sides of the rolled plate were chamfered to create parallel surfaces, and then a flat-bottom hole with an equivalent circle diameter (diameter) of 2 mm and a counterbore hole with a diameter of 6 mm were drilled on one side to prepare a pseudo-defect sample. The distance from the un-drilled sample surface to the flat-bottom hole was set to be the same as the thickness of the target material.

[0077] As a preparation before measurement, an ultrasonic flaw detector "I3-1006-T S-80mm" (frequency 10MHz, focal length 80mm) was attached to the measuring device.

[0078] The pseudo-defect sample was then placed on the measuring device, the focus was set on the counterbore hole, and measurement began. First, the counterbore hole was confirmed, and then, with the focus on the counterbore hole, the flat-bottom hole was confirmed. After that, the focus was set on the flat-bottom hole. In this state, ultrasonic flaw detection (C-scan) was performed, and the sensitivity was adjusted so that the detected flat-bottom hole diameter matched the flat-bottom hole diameter of the pseudo-defect sample. As a result, the measurement conditions were a gain (sound wave strength) of 12 dB, a measurement pitch of 2 mm, and a defect level of 38. As a result, the program sensitivity was adjusted so that reflected echo strengths of 38 or higher were detected as defects.

[0079] Next, the pseudo-defect sample was removed from the measurement device, and the bonded sputtering target was placed in the measurement device with the target material side facing up. The ultrasonic flaw detector height was set so that the focus position height of the program created with the pseudo-defect sample was the bonded layer of the sputtering target, and the scanning range of the ultrasonic flaw detector was set so that the measurement field of view was the entire bonded surface, and ultrasonic flaw detection measurement (C-scan) was performed on the bonded sputtering target. Ultrasonic waves were incident from the target material side.

[0080] The data obtained was analyzed using the analysis program attached to the ultrasonic flaw detector to obtain information on the bonding rate and maximum defect area.The surface was then finished by polishing and blasting.

[0081] The results for the sputtering targets bonded as in Example 1 are shown in Table 1.

[0082] Examples 2 to 12 Examples 2 to 12 were carried out in the same manner as Example 1, except that the amount of bonding material, wire diameter, bonding material type, target material placement position B, and overrun amount A shown in Table 1 were used, and after the target material was placed on the bonding surface of the backing plate, substantially the entire surface of the bonding layer (contact portion, bonding area on which the target material rests) between the target material and the backing plate was lightly tapped from above to remove air from the bonding layer. In Examples 2 to 12, the target material was slid in a first direction and then reversed in a second direction, in the same manner as Example 1. Example 13 In Example 13, a sputtering target was prepared in the same manner as in Example 2, except that the bonding surface of the backing plate was metallized with a Sn-Zn material, Sn-Zn (containing 9% Zn) was used as the bonding material, and the air in the bonding layer was not knocked out, and the bonding rate and maximum defect area were determined. (Comparative Example 1) In Comparative Example 1, the target material was only slid in the first direction, and was not reversed in the second direction, and other than that, the same procedures as in Examples 2 to 12 were carried out. (Comparative Example 2) In Comparative Example 2, the target material was neither slid nor reversed, nor air was hammered out, and a sputtering target was produced under the conditions shown in Table 1 without sliding or reversing the target material.

[0083] [Table 1]

[0084] In Table 1, "amount of applied bonding material" refers to the amount of bonding material applied to the bonding area 30 of the backing plate 3 in FIG. 1B. "amount of replenished bonding material" refers to the amount of bonding material replenished to the bonding area 30 of the backing plate 3 through which the target material has passed in FIG. 1D. "wire type" refers to the type of wire 5 installed in the bonding area 30 of the backing plate 3 in FIG. 1A, and stainless steel is used. "wire diameter" refers to the diameter of the wire 5. "bonding material type" refers to the material of the bonding material, and solder made of In or Sn-Zn is used. "target material installation position" refers to the position where the target material 2 is installed in FIG. 1C, and is the distance B in the first direction D1 from the first edge 31 of the bonding area 30 of the backing plate 3 to the first edge 21 of the target material 2. "Air striking" refers to striking the top surface of the target material 2 to remove air between the target material 2 and the backing plate 3 when the edge of the target material 2 is positioned on the first edge side of the bonding area of ​​the backing plate in FIG. 1C, or when the movement (sliding) of the target material 2 in the first direction D1 has finished in FIG. 1D. "Target material overrun amount" refers to the amount by which the target material 2 protrudes from the bonding area 30, which is the distance A in the first direction D1 from the second edge 32 of the bonding area 30 of the backing plate 3 to the first edge 21 of the target material 2 in FIG. 1D. "Bonding material replenishment" refers to whether or not to replenish bonding material.

[0085] As can be seen from Table 1, in Examples 1 to 13, the bonding rate was 97% or more, and the maximum defect area was 2000 mm 2 or less (i.e., the ratio of the maximum defect area to the area of ​​the bonded region is 0.6% or less). In Examples 1 to 13, the target material was less likely to peel off, and no peeling of the target material was observed even after use in a sputtering device.

[0086] In contrast, in Comparative Example 1, the bonding rate was 90.70% and the maximum defect area was 11628 mm 2 In Comparative Example 2, the bonding rate was 96.27% and the maximum defect area was 1948 mm 2In Comparative Examples 1 and 2, the target material was prone to peeling.

[0087] The present invention is not limited to the above-described embodiment, and design changes are possible without departing from the gist of the present invention.

[0088] In the above embodiment, the target material and the backing plate are formed to be long, but the target material and the backing plate may have the same length on their short sides and long sides. [Explanation of symbols]

[0089] 1. Sputtering target 2. Target material 2a Sputter surface 21 First edge 22 Second edge 3 Backing Plate 3a Main surface 30 Joint area 31 First edge 32 Second edge 4 Bonding material 6 Bonding layer 5 wire 10 Defective Areas D1 1st direction D2 2nd direction

Claims

1. A backing plate; a target material bonded to the bonding region of the backing plate via a bonding material; Equipped with a bonding area of ​​a bonding portion between the target material and the backing plate is 97% or more of an area of ​​the bonding region; A sputtering target, wherein a maximum defect area at a portion where no bonding material is present between the target material and the backing plate is 0.6% or less of an area of ​​the bonding region.

2. 2. The sputtering target according to claim 1, wherein the length of the target material is 1000 mm or more and 4000 mm or less.

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