Sputtering target, method for bonding a target material to a backplate, and method for manufacturing a sputtering target

Abstract

The present invention relates to a sputtering target, a method for bonding a target material to a backing plate, and a method for manufacturing a sputtering target. The subject of the present invention is to provide a sputtering target in which a target material is not easily peeled off. The sputtering target of the present invention comprises: a backing plate; a target material, which is bonded to a bonding area of the backing plate by means of a bonding material; and a bonding layer, which is formed by the bonding material between the backing plate and the target material, wherein the bonding area of the bonding portion between the target material and the backing plate is more than 97% relative to the area of the bonding area, and in the entire bonding area, the maximum defect area of the portion where no bonding material is present between the target material and the backing plate is less than 2% relative to the area of the entire bonding area, and the difference between the maximum thickness and the minimum thickness of the bonding layer is less than 0.5 mm.

Description

[0001] This application is a divisional application of the invention application with an application date of January 30, 2020, application number 202080008654.2, and invention name “Sputtering target, method for bonding target material to backing plate, and method for manufacturing sputtering target”. Technical Field

[0002] The present invention relates to a sputtering target, a method for bonding a target material to a backing plate, and a method for manufacturing a sputtering target. Background Art

[0003] As a conventional method for joining sputtering targets, there is the joining method described in Japanese Patent Application 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 and backing plate. The target and backing plate are then moved relative to each other while rubbing against each other to overlap. This squeezes out oxides generated on the coating surface, resulting in a brazing filler metal coating without the inclusion of oxides or bubbles. The brazing filler metal is then cooled and solidified to perform brazing.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 6-114549 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] However, it is known that in the above-mentioned conventional sputtering target bonding method, there is a concern that the bonding between the target material and the backing plate is insufficient, resulting in the possibility of target material peeling off during sputtering. The inventors of the present application conducted in-depth research and found that in the conventional method, the ratio of the actual bonding area (bonding area) to the area of the region to be bonded to the backing plate (bonding area) (bonding rate) is small, and the area of the portion with the largest area (maximum defect area) among the portions where no bonding material exists (unbonded portions) between the target material and the backing plate is large. As a result, they discovered a relationship between the bonding rate and the maximum defect area and target material peeling off.

[0009] Therefore, an object of the present invention is to provide a sputtering target capable of realizing a sputtering target in which a target material is unlikely to be separated during sputtering, a method for bonding a target material to a backing plate, and a method for manufacturing a sputtering target.

[0010] Means for solving problems

[0011] In order to solve the above-mentioned problems, one embodiment of a sputtering target includes:

[0012] back panel; and

[0013] a target material bonded to a bonding region of the backing plate (a region of the backing plate to which the target material is to be bonded) by means of a bonding material,

[0014] The bonding area of the bonding portion (bonded portion) between the target and the backing plate is 97% or more relative to the area of the bonding region.

[0015] The maximum defect area of the unbonded portion between the target and the backing plate is 0.6% or less relative to the area of the bonded region.

[0016] According to the above-described 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 be peeled off.

[0017] In one embodiment of the sputtering target, the length of the target material is not less than 1000 mm and not more than 4000 mm.

[0018] According to the above-described embodiment, it is possible to manufacture a sputtering target in which the target material is unlikely to be peeled off even in a long sputtering target.

[0019] In addition, one embodiment of a method of bonding a target to a backing plate is a method of bonding a target to a backing plate using a bonding material, comprising:

[0020] a step of applying a bonding material to a region (bonding region) on the main surface of the backing plate to be bonded to the target material;

[0021] a step of sliding the target in the first direction along the main surface of the backing plate so that the end edge (first end edge) of the target moves from the first end edge side of the bonding region of the backing plate to a position exceeding the second end edge opposite to the first end edge in the bonding region of the backing plate; and

[0022] The step of sliding the target along the main surface of the backing plate in a second direction opposite to the first direction to align the target with the bonding region of the backing plate.

[0023] Hereinafter, sliding movement of the target in the first direction may also be referred to as “sliding”, and sliding movement of the target in the second direction may also be referred to as “reverse sliding”.

[0024] According to the aforementioned embodiment, the target is slid relative to the backing plate in a first direction and then slid in the opposite direction in a second direction, thereby aligning the bonding areas of the target and the backing plate. This improves the bonding rate between the target and the backing plate, and reduces the size of the largest defect area, which is the largest area in the unbonded portion. Consequently, a sputtering target can be manufactured that is less susceptible to target delamination.

[0025] In addition, in one embodiment of the method of bonding a target to a backing plate,

[0026] The target material and the back plate are formed into a long strip shape,

[0027] The end edge of the target is formed along the long side direction of the target,

[0028] The first end edge and the second end edge of the bonding region of the back plate are formed along the long side direction of the back plate and are opposite to each other in the short side direction of the back plate.

[0029] The target is slidably moved relative to the backing plate in the short side direction of the backing plate.

[0030] According to the aforementioned embodiment, in the case of the long target and the backing plate, the moving distance of the target relative to the backing plate can be reduced, and the operation time can be shortened.

[0031] In addition, in one embodiment of the method of bonding a target to a backing plate,

[0032] The method comprises: before the step of applying the bonding material, a step of arranging a plurality of wires on the main surface of the back sheet;

[0033] During the movement of the target in the first direction and the second direction, the target is caused to slide on the wire.

[0034] According to the above embodiment, the target material is slid on the wire, so 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, thereby improving the joining rate. In addition, the wire functions as a spacer, so the thickness of the joining layer formed by the joining material between the target material and the backing plate can be kept constant.

[0035] In one embodiment of the method of bonding a target to a backing plate, the wire has a diameter of 0.05 mm to 0.5 mm.

[0036] According to the above-described embodiment, disconnection can be prevented, and non-uniformity in the thickness of the bonding layer formed by the bonding material can be prevented.

[0037] In addition, one embodiment of the method for bonding a target to a backing plate includes a step of supplementing bonding material on the first end edge side of the bonding region of the backing plate between the step of moving the target in the first direction and the step of moving the target in the second direction.

[0038] According to the aforementioned embodiment, the bonding material is supplemented on the first end edge side of the bonding area of the back plate, so that the bonding material can be supplemented on the first end edge side of the bonding area where the bonding material easily becomes insufficient, which can further improve the bonding rate and further reduce the maximum defect area.

[0039] In addition, in one embodiment of the method of joining a target material to a backing plate, in the process of moving the target material in the first direction, when the end edge (first end edge) of the target material is moved to a position exceeding the second end edge of the joining area of the backing plate, if the distance in the first direction from the second end edge of the joining area of the backing plate to the end edge (first end edge) of the target material is set to A, and the width of the joining area in the first direction is set to W, then 0.03≤A / W<1.0.

[0040] According to the aforementioned embodiment, the moving distance of the target relative to the backing plate can be reduced, the bonding rate can be improved, and the maximum defect area can be reduced.

[0041] In addition, in one embodiment of the method of joining a target material to a backing plate, in the moving process of the target material in the first direction, when the end edge (first end edge) of the target material is arranged on the first end edge side of the joining area of the backing plate, if the distance in the first direction from the first end edge of the joining area of the backing plate to the end edge (first end edge) of the target material is set to B, and the width of the joining area in the first direction is set to W, then 0≤B / W<2.0.

[0042] According to the above embodiment, the moving distance of the target relative to the backing plate can be reduced, and the target can be slid after being placed on the backing plate, thereby improving the bonding rate and reducing the size of the maximum defect area.

[0043] In one embodiment of the method for producing a sputtering target, the target material and the backing plate are bonded together using the bonding method to produce the sputtering target.

[0044] According to the above embodiment, the bonding rate can be improved when bonding the target and the backing plate, and the size of the largest defect area in the unbonded portion can be reduced. Therefore, a sputtering target in which the target is less likely to peel off can be manufactured.

[0045] Effects of the Invention

[0046] According to the sputtering target, the method of bonding a target material to a backing plate, and the method of manufacturing a sputtering target of the present invention, a sputtering target in which a target material is unlikely to be peeled off can be manufactured. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] [ Figure 1A] is an explanatory diagram showing an embodiment of the method of bonding a target material to a backing plate of the present invention.

[0048] [ Figure 1B ] is an explanatory diagram showing an embodiment of the method of bonding a target material to a backing plate of the present invention.

[0049] [ Figure 1C ] is an explanatory diagram showing an embodiment of the method of bonding a target material to a backing plate of the present invention.

[0050] [ Figure 1D ] is an explanatory diagram showing an embodiment of the method of bonding a target material to a backing plate of the present invention.

[0051] [ Figure 1E ] is an explanatory diagram showing an embodiment of the method of bonding a target material to a backing plate of the present invention.

[0052] [ Figure 2A ] is a simplified cross-sectional view showing a state in which no bonding material exists in the bonding layer between the target material and the backing plate.

[0053] [ Figure 2B ] is a simplified cross-sectional view showing a state in which no bonding material exists in the bonding layer between the target material and the backing plate.

[0054] [ Figure 3A ] is a schematic diagram showing the state of the bonding material between the target material and the backing plate of the sputtering target of the present invention.

[0055] [ Figure 3B ] is a schematic diagram showing the state of the bonding material between the target material and the backing plate of the sputtering target of the comparative example. DETAILED DESCRIPTION

[0056] Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings.

[0057] (Implementation Method)

[0058] Figures 1A to 1E 1 is an explanatory diagram showing an embodiment of a method for bonding a target material to a backing plate (hereinafter referred to as a "bonding method") of the present invention. Figures 1A to 1E As shown, this method is a method of bonding the target 2 and the backing plate 3 using a bonding material 4 .

[0059] like Figure 1AAs shown, prepare a target 2 and a backing plate 3. The target 2 is formed into a long strip of plate. The length of the long side direction of the target 2 is, for example, more than 1000 mm, preferably more than 1500 mm, more preferably more than 2000 mm, further preferably more than 2200 mm, and less than 4000 mm, preferably less than 3500 mm, more preferably less than 3200 mm, and further preferably less than 3000 mm. The length of the short side direction of the target 2 is, for example, more than 100 mm, preferably more than 120 mm, more preferably more than 130 mm, further preferably more than 150 mm, and less than 2000 mm, preferably less than 1000 mm, more preferably less than 500 mm, and further preferably less than 300 mm. It should be noted that the length in the long side direction and the length in the short side direction may be the same or different. In addition, the thickness of the target 2 is, for example, more than 5 mm and less than 40 mm, preferably more than 10 mm and less than 30 mm, more preferably more than 12 mm and less than 25 mm. In the present invention, even when a target for a large flat panel display is used, it is possible to improve the bonding rate and reduce the maximum defect area in the entire bonding region.

[0060] Furthermore, 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 1 or more and 30 or less, preferably 5 or more and 25 or less, more preferably 6 or more and 20 or less, further preferably 7 or more and 18 or less, and particularly preferably 8 or more and 15 or less. Thus, although the sputtering target has an elongated shape, the effect of the reverse sliding step is easily exhibited, and a sputtering target having a high bonding rate and a small maximum defect area can be manufactured.

[0061] The target 2 has a sputtering surface 2a on its top surface. When viewed from the top surface, the target 2 has a first end edge 21 and a second end edge 22 corresponding to the long sides. The first end edge 21 and the second end edge 22 are formed along the long side of the target 2 and are arranged so as to face each other in the short side direction of the target 2.

[0062] The target 2 has a surface (bonding surface) on the back side of the sputtering surface 2a, which serves as the top surface, to be bonded to the backing plate. The size of the bonding surface is typically substantially the same as that of the target 2, but it can be smaller than the area of the target 2 (longitudinal length × short-side length; when a rounded portion is included, the area in the top view) to remove burrs generated on the bonding surface during machining and corners that may cause abnormal discharge. The area of the bonding surface can be typically 95% or more, preferably 98% or more, and more preferably 99% or more of the area of the target 2.

[0063] During sputtering of the target material 2, the inert gas ionized by sputtering collides with the sputtering surface 2a. Target atoms contained in the target material 2 are knocked out from the sputtering surface 2a hit by the ionized inert gas. These knocked-out atoms accumulate on a substrate disposed opposite the sputtering surface 2a, forming a thin film on the substrate.

[0064] The material for making the target 2 is not particularly limited as long as it is a material composed of ceramics or sintered bodies such as metals, alloys, oxides, nitrides, etc. that can be commonly used in film formation based on sputtering. The target material can be appropriately selected according to the use and purpose. For example, it can be made of 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, nickel and their alloys, tin-doped indium oxide (ITO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), and In-Ga-Zn composite oxides (IGZO). The material constituting the target 2 is not limited to these materials. For example, as the material in the target 2 for electrodes and wiring materials, Al and Al alloys are preferred, and it is particularly preferred to use, for example, Al with a purity of 99.99% or more, more preferably 99.999% or more, and Al alloys (Al-Cu, Al-Si, Al-Cu-Si) with these Al as the base material. High-purity Al has a large linear thermal expansion coefficient, so it is easily warped by the heat during sputtering and easily peels off from the backplane. However, according to the present invention, the bonding rate can be improved, the maximum defect area can be reduced, and peeling off from the backplane can be prevented.

[0065] The backboard 3 is formed into a long strip of plate. The length of the long side direction of the backboard 3 is, for example, greater than 1000 mm and less than 4500 mm, preferably greater than 1500 mm and less than 4000 mm, more preferably greater than 2000 mm and less than 3500 mm, and further preferably greater than 2500 mm and less than 3200 mm. The length of the short side direction of the backboard 3 is, for example, greater than 100 mm and less than 2000 mm, preferably greater than 150 mm and less than 1200 mm, more preferably greater than 180 mm and less than 750 mm, and further preferably greater than 200 mm and less than 350 mm. Here, one direction of the short side direction of the backboard 3 is set as the first direction D1, and the other direction of the short side direction of the backboard 3 and the direction opposite to the first direction D1 is set as the second direction D2.

[0066] The backing plate 3 has a bonding region 30 (shown by hatching) on the main surface 3a of the upper surface. The bonding region 30 is the region to be bonded to the target 2. The shape of the bonding region 30 corresponds to the shape of the target 2. In other words, the size of the bonding region 30 is substantially the same as the size of the bonding surface of the target 2, preferably the size of the target 2.

[0067] When viewed from above, the bonding region 30 has a first end edge 31 and a second end edge 32 corresponding to the long sides. The first end edge 31 and the second end edge 32 are formed along the long sides of the back plate 3, and are arranged to face each other in the short side direction of the back plate 3. The second end edge 32 is located in the first direction D1 relative to the first end edge 31.

[0068] The back plate 3 is made of a conductive material, such as a metal or its alloy, etc. Examples of the metal include copper, copper alloys, aluminum, aluminum alloys, titanium, and SUS.

[0069] The bonding surface of the target 2 and the bonding area 30 of the back plate 3 are preferably flat. From the perspective of easily reducing the slippage and the maximum defect area when the target 2 slides or reverses, the flatness is less than 1.0 mm, preferably less than 0.5 mm, and more preferably less than 0.3 mm. The so-called flatness is a numerical value indicating the smoothness (uniformity) of a plane, and refers to the size of the plane warp that is correct in the geometric sense of a plane body. In addition, from the perspective of preventing the flow of the bonding material on the bonding area 30 of the back plate 3 during bonding, the back plate 3 only needs the main surface 3a of the upper surface to be roughly parallel, preferably parallel, to its back side. From the perspective of easily and constantly applying force to the target 2 when the target 2 slides or reverses, the target 2 only needs the sputtering surface 2a of the upper surface to be roughly parallel, preferably parallel, to the bonding surface that is its back side.

[0070] The bonding process is performed while the target 2, the backing plate 3 and the bonding material 4 are heated. Figure 1B As shown in FIG. 1 , the bonding material 4 is applied to the entire bonding area 30 of the back sheet 3. The amount of the bonding material 4 applied is 1.5×10 -6 kg / mm 2 above, preferably 2.5×10 -6 kg / mm 2 More than 4.5×10 -6 kg / mm 2 More preferably, 10×10 -6 kg / mm 2 More than 14×10 -6 kg / mm 2 The upper limit is not particularly limited, but is preferably 50×10 -6 kg / mm 2 Below, more preferably 35×10 -6 kg / mm 2 Below, more preferably 25×10 -6 kg / mm 2The bonding material 4 includes, for example, a metal having a low melting point (e.g., 723K or less) such as solder or brazing filler metal. The solder material is, for example, a metal such as indium, tin, zinc, lead, silver, copper, bismuth, cadmium, antimony, or an alloy thereof, and is, for example, an In material, an In-Sn material, a Sn-Zn material, a Sn-Zn-In material, an In-Ag material, a Sn-Pb-Ag material, a Sn-Bi material, a Sn-Ag-Cu material, a Pb-Sn material, a Pb-Ag material, a Zn-Cd material, a Pb-Sn-Sb material, a Pb-Sn-Cd material, a Pb-Sn-In material, or a Bi-Sn-Sb material. Generally, a solder material having a low melting point such as In, an In alloy, Sn, or a Sn alloy is preferably used. The bonding is performed at a temperature above the melting point of the bonding material 4, preferably above 140°C, more preferably above 150°C and below 300°C. If the viscosity of the molten bonding material 4 is above 0.5 mPa·s, preferably above 1.0 mPa·s, more preferably above 1.5 mPa·s, and below 5 mPa·s, preferably below 3 mPa·s, more preferably below 2.5 mPa·s, the bonding rate can be improved and the maximum defect area can be reduced. In addition, before the target 2 and the backing plate 3 are bonded, the bonding surface of the target 2 and the backing plate 3, and the bonding surface of the backing plate 3 and the target 2 can be subjected to a pretreatment (metallization treatment) for improving wettability with the bonding material 4. With regard to the pretreatment, roughening, graining, embossing and metallization based on grinding, lapping, etc. can be performed, and a concave-convex surface such as a lapping surface, a grinding surface, a graining surface, an embossing surface, or a metallization layer can be provided on each bonding surface of the target 2 and the backing plate 3. For example, grinding can be performed by hand or by using a grinding machine equipped with a grinding material using abrasives coated on paper or a fiber substrate. Metallization can be performed by coating a metallization material on the bonding surface and performing ultrasonic irradiation or the like. As a metallization material, it can be selected from the same materials as the bonding material 4, for example, In materials and Sn-Zn materials can be used. The thickness of the metallization layer is greater than 1 μm and less than 100 μm. If it is within this range, it is easy to ensure wettability with the bonding material 4 and to improve the bonding rate. It should be noted that the unbonded portion of the target material 2 and the backing plate 3 can be masked in advance with a heat-resistant tape to prevent the adhesion of the bonding material 4 and the formation of the metallization layer.

[0071] like Figure 1C As shown, the first edge 21 of the target 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 2 is preferably arranged so as to overlap with the bonding region 30.

[0072] like Figure 1DAs shown, the target material 2 is then slid in the first direction D1 along the main surface 3a of the backing plate 3 in such a manner that the first end edge 21 of the target material 2 moves from the side of the first end edge 31 of the bonding area 30 of the backing plate 3 to a position exceeding the second end edge 32 of the bonding area 30 of the backing plate 3.

[0073] like Figure 1E As shown, the target 2 is then slid along the main surface 3a of the backing plate 3 in the second direction D2 to align the bonding area 30 of the target 2 and the backing plate 3. The target 2 and the backing plate 3 are then precisely aligned. While the target 2 and the backing plate 3 are fixed by placing a weight or clamping them with a vise, a bench vise, or a clamp, the bonded body of the target 2 and the backing plate 3 is cooled to solidify the bonding material 4. Thus, the target 2 and the backing plate 3 are bonded by the bonding material 4 to produce the sputtering target 1.

[0074] According to the bonding method, the target 2 is slid relative to the backing plate 3 in the first direction D1 and then slid in the reverse direction D2, thereby aligning the bonding area 30 of the target 2 and the backing plate 3. In this way, by not only sliding the target 2 but also sliding in the reverse direction, the bonding material 4 can be pulled back in the second direction D2 by surface tension while the target 2 slides in the reverse direction, thereby reducing the space between the target 2 and the backing plate 3 where the bonding material 4 does not exist, and reducing the number of unbonded areas.

[0075] Therefore, in the bonding between the target 2 and the backing plate 3 , the bonding rate can be improved and the maximum defect area can be reduced.

[0076] The bonding rate refers to the ratio of the bonding area of the bonding portion between the target 2 and the backing plate 3 to the area of the bonding region 30 .

[0077] Specifically, the bonding area refers to the total area of a portion where no region where the bonding material is absent is detected when observing the bonding layer between the target 2 and the backing plate 3 in the thickness direction.

[0078] The so-called maximum defect area refers to the area of the largest portion of the portion between the target 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 an area, i.e., a space, in the thickness direction of the bonding layer where the bonding material is not present, or a portion where foreign matter other than the bonding material, such as oxides of the bonding material, is detected. This includes not only the entire thickness direction of the bonding layer but also the case where the bonding material is not present locally. For example, Figure 2A As shown, in the bonding layer 6 between the target 2 and the backing plate 3, a space S where no bonding material 4 is present may exist in a portion of the bonding layer 6 in the thickness direction (vertical direction in the figure), or, as shown in FIG. Figure 2BAs shown, in the bonding layer 6 between the target 2 and the backing plate 3, there may be a space S where the bonding material 4 is not present throughout the thickness direction of the bonding layer 6 (the vertical direction in the figure). The area where the bonding material is not present can be detected using the measurement method described below. For example, when ultrasonic flaw detection is used, if there is a space where the bonding material is not present in the bonding layer, the incident ultrasonic wave is reflected by the interface, thereby identifying the defect.

[0079] Therefore, according to the present invention, the bonding rate between the target 2 and the backing plate 3 can be improved and the maximum defect area can be reduced, so that a sputtering target 1 in which portions with low bonding strength are unlikely to be formed and the target 2 is unlikely to be peeled off can be manufactured.

[0080] Thus, the present invention has found that by focusing on both the bonding rate and the maximum defect area, the target 2 is less likely to peel off during sputtering. Specifically, regarding the bonding rate, as the bonding rate increases, the area without the bonding material 4 can be reduced, and the target 2 is less likely to peel off.

[0081] On the other hand, with respect to the maximum defect area, if the maximum defect area increases, large defects will be generated locally, the electrical and thermal conductivity of this portion will deteriorate, heat concentration will occur in this portion, and the bonding material 4 will melt, thereby making it easier for the target material 2 to peel off. Therefore, if the maximum defect area is reduced, large defects will not be generated locally, and the target material 2 will be less likely to peel off.

[0082] Furthermore, according to the above-described bonding method, the target 2 is slid relative to the backing plate 3 in the short side direction of the backing plate 3. Thus, in the case of long targets 2 and backing plate 3, the moving distance of the target 2 relative to the backing plate 3 can be reduced, thereby shortening the operation time.

[0083] It is preferable to coat the bonding material 4 (see Figure 1B ) before, such as Figure 1AAs shown, a plurality of wires 5 are arranged on the main surface 3a of the back plate 3. The material of the wire 5 is, for example, stainless steel, copper, etc. Specifically, the wire 5 is arranged in the bonding area 30 in a manner extending in the first direction D1, and the plurality of wires 5 are arranged at intervals in a direction orthogonal to the first direction D1. Moreover, during the movement of the target 2 in the first direction D1 and the second direction D2, the target 2 is slid on the wire 5. Thus, since the target 2 is slid on the wire 5, the target 2 can be easily moved. As long as the target 2 can be moved in parallel, the number of arranged wires 5 is not particularly limited, and is preferably 5 or more, more preferably 7 or more, and further preferably 9 or more. In addition, by using the wire 5 as a spacer, the thickness of the bonding layer formed by the bonding material 4 can be made a fixed value. The thickness of the bonding layer is generally more than 0.03mm and less than 1.5mm, preferably more than 0.05mm and less than 1mm, more preferably more than 0.08mm and less than 0.5mm, more preferably more than 0.1mm and less than 0.35mm. The deviation of the thickness of the bonding layer, that is, the difference between the maximum thickness and the minimum thickness of the bonding layer is preferably less than 0.5mm, more preferably less than 0.4mm, more preferably less than 0.3mm, and particularly preferably less than 0.25mm. The deviation of the thickness of the bonding layer can be calculated by measuring the thickness of the bonding layer at multiple arbitrary points (preferably more than 4 points) around the bonding layer of the sputtering target 1. The thickness of the bonding layer can be obtained from the horizontal measurement of the bonding layer using a ruler, a vernier caliper, a depth gauge, etc. In addition, the deviation of the thickness of the bonding layer represents a numerical value roughly the same as the deviation of the height of the target material 2 in the sputtering target 1 from the reference plane (for example, the bonding surface of the back plate), and therefore it can also be obtained by measuring the height of the target material 2 in the sputtering target 1 using, for example, an altimeter. By increasing the bonding rate of the sputtering target 1 and reducing the size of the largest defect area in the unbonded portion, and further reducing the variation in the thickness of the bonding layer, a sputtering target that is less likely to cause the target material to peel off can be obtained.

[0084] The diameter of the wire 5 is preferably 0.05 mm to 0.5 mm, more preferably 0.1 mm to 0.3 mm. This makes it difficult for the wire 5 to break, and can reduce the variation in the thickness of the bonding layer.

[0085] It is preferable to move the target 2 in the first direction D1 (see Figure 1D ) and the moving step of the target 2 in the second direction D2 (refer to Figure 1E ), the bonding material 4 is supplemented on the first edge 31 side of the bonding area 30 of the back plate 3. Specifically, Figure 1DIn the state shown, the bonding material 4 is added to the portion of the bonding region 30 that is not covered by the target material 2. Thus, since the bonding material 4 is added to the first edge 31 of the bonding region 30 of the backing plate 3, the bonding material 4 can be added to the first edge 31 of the bonding region 30 where the bonding material 4 is likely to be insufficient as the target material 2 moves. This can further improve the bonding rate and further reduce the maximum defect area. The amount of bonding material 4 added is preferably 0.5×10 -6 kg / mm 2 More than 0.8×10 -6 kg / mm 2 More preferably, 1.0×10 -6 kg / mm 2 The upper limit is not particularly limited, but is preferably 20×10 -6 kg / mm 2 Below, more preferably 10×10 -6 kg / mm 2 Below, more preferably 7.0×10 -6 kg / mm 2 the following.

[0086] Preferably, in the process of moving the target 2 in the first direction D1, Figure 1D As shown, when the first end edge 21 of the target 2 is moved to a position exceeding the second end edge 32 of the bonding area 30 of the back plate 3, if the distance in the first direction D1 from the second end edge 32 of the bonding area 30 of the back plate 3 to the first end edge 21 of the target 2 is set to A, and the width of the bonding area 30 in the first direction D1 is set to W, then 0.03≤A / W<1.0, preferably 0.05≤A / W≤0.8, and more preferably 0.06≤A / W≤0.6. Specifically, 10mm≤A≤150mm, preferably 12mm≤A≤120mm, and preferably 150mm≤W≤300mm. In this way, the moving distance of the target 2 relative to the back plate 3 can be reduced, the bonding rate can be improved, and the maximum defect area can be reduced.

[0087] Preferably, in the process of moving the target 2 in the first direction D1, Figure 1CAs shown, when the first end edge 21 of the target 2 is arranged on the first end edge 31 side of the bonding area 30 of the backing plate 3, if the distance in the first direction D1 from the first end edge 31 of the bonding area 30 of the backing plate 3 to the first end edge 21 of the target 2 is set to B, and the width of the first direction D1 of the bonding area 30 is set to W, then the lower limit of B / W is greater than 0, preferably greater than 0.03, more preferably greater than 0.10, and further preferably greater than 0.20, and the upper limit of B / W is less than 2.0, preferably less than 1.5, more preferably less than 1.2, further preferably less than 1.0, and particularly preferably less than 0.8. Specifically, 0mm≤B≤300mm, preferably 5mm≤B / W≤200mm, and preferably 150mm≤W≤300mm. As a result, the moving distance of the target 2 relative to the backing plate 3 can be reduced, the bonding rate can be improved, and the maximum defect area can be reduced.

[0088] From the perspective of preventing unnecessary movement and detachment of the bonding material placed in the bonding area, the speed of movement (sliding) in the first direction D1 and the speed of movement (reverse sliding) in the second direction D2 of the target material 2 are preferably 100 mm / second or less, more preferably 50 mm / second or less, and even more preferably 30 mm / second or less. There is no particular lower limit, but from the perspective of productivity, the lower limit is 1 mm / second or more, preferably 5 mm / second or more.

[0089] At the stage where the end edge of the target material 2 is arranged on the first end edge side of the bonding area of the back plate, and / or at the stage where the movement (sliding) of the target material 2 in the first direction D1 is completed, it is preferred to provide a process of imparting vibration from the upper surface of the target material 2 and removing the air that may be present in the bonding layer. As a means of imparting vibration, a method of gently tapping the upper surface of the target material or a method of applying vibration in a direction parallel to the upper surface of the target material 2 can be performed. Regarding the range of applied vibration, it is preferred that at the stage where the end edge of the target material 2 is arranged on the first end edge side of the bonding area of the back plate, vibration is applied to the entire bonding layer between the target material and the back plate (bonding area where the target material is placed), and at the stage where the movement (sliding) of the target material 2 in the first direction D1 is completed, vibration is applied to the front head of the movement (reverse sliding) action in the second direction D2. Regarding the direction of applying vibration, it is preferred to apply vibration from the center of the bonding layer between the target material and the back plate (bonding area where the target material is placed) toward the periphery. In this way, air present in the bonding layer can be removed, thereby improving the bonding rate and reducing the maximum defect area. In particular, in the stage where the edge of the target material 2 is arranged on the first edge side of the bonding area of the backing plate, there is a high possibility that air is trapped in the bonding layer between the target material and the backing plate (the bonding area where the target material is placed). Therefore, by providing an air removal process, the effects of improving the bonding rate and reducing the maximum defect area can be further exerted.

[0090] Next, a description will be given of a method for manufacturing the sputtering target 1. As described above, the sputtering target is manufactured by bonding the target material and the backing plate using the bonding method.

[0091] In the manufacture method of the present invention, target material can be processed into roughly plate-like, and the method for processing into plate-like is not particularly limited. About the target material made of metal material, after the rectangular parallelepiped, cylindrical, cylindrical target material obtained by, for example, melting, casting can be supplied to the plastic working such as rolling processing, extrusion processing, forging processing, implement machining (cutting processing, milling processing, end milling processing etc.) such as cutting, grinding, grinding, manufacturing target material of desired size, surface state. Rolling processing is such as recorded in Japanese Unexamined Patent Publication No. 2010-132942, International Publication No. 2011 / 034127. Extrusion processing is such as recorded in Japanese Unexamined Patent Publication No. 2008-156694. Forging is described in, for example, Japanese Patent Publication No. 2017-150015, Japanese Patent Publication No. 2001-240949, or Aluminum Technology Handbook (Compiled by the Light Metals Association Aluminum Technology Handbook Editorial Committee, Carlos Publishing, new edition, issued on November 18, 1996). Using the joining method of the present invention, a machined plate-shaped target material is joined to a backing plate to manufacture a sputtering target. In addition, as a target material, a target material that has been machined to a specified size can be purchased for use, or a target material obtained by removing the backing plate and then removing the joining material from the following sputtering target can be used as a target material, wherein the sputtering target is a sputtering target that produces an abnormality when joined to the backing plate in the manufacturing process of the sputtering target 1 and does not meet the product specifications. It should be noted that, as needed, the surface of the sputtering target after joining can also be subjected to finishing based on cutting and grinding.

[0092] In the method for producing a sputtering target of the present invention, since the bonding method of the present invention is used, a sputtering target with improved quality can be obtained.

[0093] Next, the sputtering target 1 bonded by the above-described bonding method will be described.

[0094] like Figure 1E As shown, the sputtering target 1 includes 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 .

[0095] Figure 3A This is a schematic diagram showing the state of the bonding material 4 between the target material 2 of the sputtering target 1 and the backing plate 3 . Figure 3AIn the figure, the defective portion (unbonded portion) 10 in which the bonding material 4 is not present in the bonding area 30 is indicated by hatching. The defective portion 10 can be measured, for example, by ultrasonic flaw detection or transmission X-ray observation, but when the area of the bonding area is large, ultrasonic flaw detection is preferably used. As ultrasonic flaw detection devices, FS LINE and FS LINE Hybrid manufactured by Hitachi PowerSolutions Co., Ltd., phased array ultrasonic flaw detection imaging device PDS and ultrasonic flaw detection imaging device ADS71000 manufactured by KJTD Co., Ltd. can be used. In addition, when determining the bonding rate and the maximum defect area by ultrasonic flaw detection, it is necessary to use a suspected defective sample provided with a flat-bottomed hole of a specified size and adjust the ultrasonic flaw detection measurement conditions for identifying the reflected wave from the defective portion. The propagation speed of ultrasonic waves varies depending on the raw material. Therefore, from the perspective of making the measurement sensitivity and conditions consistent, it is preferred that the suspected defective sample be made of the same raw material as the raw material on the ultrasonic incident side of the sputtering target 1. In addition, it is preferable that the distance between the ultrasonic incident surface and the bottom surface of the flat-bottomed hole in the suspected defective sample is equal to the distance between the ultrasonic incident surface and the bonding layer of the sputtering target 1 .

[0096] like Figure 3A As shown, the area of the portion where the defective portion 10 is not detected between the target material 2 and the backing plate 3 is 97% or more relative to the area of the bonding area 30. That is, the bonding rate is 97% or more, preferably 98% or more, and more preferably 98.5% or more. In addition, the maximum defect area of the defective portion 10 in the bonding layer between the target material 2 and the backing plate 3 is 2% or less relative to the area of the bonding area 30, preferably 1% or less, more preferably 0.6% or less, further preferably 0.3% or less, further preferably 0.1% or less, and particularly preferably less than 0.05%. For example, when the area of the bonding area 30 is 200mm×2300mm, the maximum defect area is 2000mm 2 the following.

[0097] 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, thereby preventing the target material 2 from peeling off. The length of the target material 2 is preferably 1000 mm to 4000 mm, and it is possible to manufacture a sputtering target 1 that is not easily peeled off even in a long sputtering target 1.

[0098] The upper limit of the bonding rate is 100%. However, considering the possibility of sputtering targets becoming out of specification due to abnormalities during bonding, or the ease of target material peeling off when removing the backing plate after the sputtering target has been used for sputtering, the bonding rate is preferably 99.99% or less, more preferably 99.95% or less, and even more preferably 99.90% or less. It should be noted that the target material can be peeled off from the sputtering target by heating the sputtering target to a temperature above the melting point of the bonding material used for bonding to soften or melt the bonding layer, and then physically destroying the bonding layer as needed.

[0099] The lower limit of the ratio of the maximum defect area to the area of the bonding region 30 is not particularly limited. However, from the perspective of further suppressing warping of the sputtering target due to heat generated during sputtering, the lower limit is 0.001% or greater, preferably 0.003% or greater, more preferably 0.005% or greater, and even more preferably 0.008% or greater. When the lower limit of the ratio of the maximum defect area is greater than this value, deformation of the target material caused by heat during sputtering is mitigated by the localized defects, thereby reducing warping of the sputtering target.

[0100] In contrast, Figure 3B FIG. 1 shows a sputtering target 100 of a comparative example when the target is bonded to the backing plate by sliding the target in the first direction D1, and shows the state of the bonding material between the target and the backing plate. Figure 3B As shown, Figure 3A In contrast, the proportion of defective areas 10 is high, the bonding rate is low, and the maximum defect area of the defective areas 10 is large. Thus, when the target material is simply sliding, the bonding between the target material and the backing plate deteriorates, resulting in the target material being easily delaminated. This tendency to delaminate becomes particularly pronounced in sputtering targets with long targets or large bonding areas.

[0101] In a suitable embodiment of the sputtering target of the present invention, a wire may be provided between the target and the backing plate, i.e., in the bonding layer. Preferably, a plurality of wires are arranged at intervals in a direction perpendicular to the long side direction of the target 2, and more preferably, the wires are arranged at equal intervals. In addition, the ratio of the number of wires provided in the bonding layer to the length of the target 2 (number of wires (roots) / length of the target 2 (mm)) is greater than 0.002 and less than 0.008, preferably greater than 0.003 and less than 0.007, more preferably greater than 0.003 and less than 0.006. By having wires in the bonding layer as described above, it is easy to ensure the thickness of the bonding layer, and it is easier to make the thickness of the bonding layer a fixed value, so that it is possible to manufacture a sputtering target 1 that can increase the bonding rate of the sputtering target 1, reduce the maximum defect area, and prevent the target 2 from peeling off.

[0102] (Example 1)

[0103] A rolled plate made of high-purity Al with a purity of 99.999% was prepared and cut using a portal machining center to produce a target material of 200 mm × 2300 mm × t16 mm (the area of the bonding area is 4.5 × 10 5 mm 2 ), 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 (so-called target width) in the target movement step was 200 mm.

[0104] The target and backing plate are heated on a hot plate to a temperature above the melting point of the bonding material.

[0105] The Sn-Zn-In alloy material is melted on the target's bonding surface, and the In material is melted on the backing plate's bonding surface. The bonding surfaces of the two materials are then metallized using an ultrasonic soldering iron. After metallization, the Sn-Zn-In alloy material, In material oxides, and excess Sn-Zn-In alloy material and In material are removed from the target and backing plate's bonding surfaces using a scraper.

[0106] Ten SUS wires with a diameter of 0.2 mm were placed at approximately equal intervals on the metallized backplane's bonding surface, perpendicular to the backplane's long sides. Furthermore, an indium bonding material was applied from above the SUS wires onto the bonding surface. The amount of indium bonding material applied from above the SUS wires to the bonding surface was 7.80 kg.

[0107] The target is oriented so that its bonding surface is parallel to and opposite to the bonding surface of the backing plate. One of its long sides is positioned on a line (target placement position B = 0) so that it overlaps with one of its long sides. The target is then slid toward the desired bonding position. The target is slid such that the ratio A / W of the distance (excess) A extending from the desired bonding position relative to the target width W is 0.1625. The target is then gently tapped from above at the front end of the target in the second direction D2 of movement (reverse sliding) to remove air.

[0108] The target was then slid to the specified bonding position. The target position was finely adjusted to maintain the specified bonding position. A weight was placed on the target to secure the target and backing plate. The bonded structure was then cooled to produce a sputtering target. The thickness of the sputtering target's bonding layer was measured using a vernier caliper at six locations, including both ends of the long sides and the center. The difference between the maximum and minimum bonding layer thicknesses was calculated, resulting in a value of 0.2 mm.

[0109] After the In material solidified, the warpage caused by the difference in linear expansion coefficient between the target material and the backing plate was corrected to obtain a target. The bonding rate and maximum defect area were measured using an ultrasonic flaw detector FS-LINE manufactured by Hitachi Power Solutions Co., Ltd.

[0110] The measurement of bonding rate and maximum defect area is carried out according to the following steps. First, prepare the following suspected defect sample: use a high-purity Al rolled plate with a purity of 99.999%, plane cut both sides of the rolled plate to form parallel surfaces, and then open a circle with an equivalent diameter (diameter) from one side. 2mm flat bottom hole, At this time, the distance from the surface of the sample (which has not yet been drilled) to the flat-bottom hole is made equal to the thickness of the target material.

[0111] As preparation before the measurement, an ultrasonic flaw detection element "I3-1006-TS-80mm" (frequency 10 MHz, focal length 80 mm) was attached to the measuring device.

[0112] Next, the suspected defective sample was placed in the measuring device, with the focus aligned with the countersunk hole, and measurement began. First, the countersunk hole was identified, and then, with the focus aligned with the countersunk hole, the flat-bottom hole was identified. Finally, the focus was aligned with the flat-bottom hole. Ultrasonic flaw detection (C-scan) was performed in this state, and sensitivity was adjusted so that the detected flat-bottom hole diameter matched that of the suspected defective sample. As a result, the measurement conditions were set to 12dB for the gain (sound wave intensity), 2mm for the measurement pitch, and 38 for the defect level. Thus, the program sensitivity was adjusted so that a reflected echo intensity of 38 or higher was detected as a defect.

[0113] Next, the suspected defect sample is removed from the measuring apparatus and the bonded sputtering target is placed in the measuring apparatus with the target material side facing the top surface. The ultrasonic flaw detection element height is set so that the focal point height of the program created for the suspected defect sample corresponds to the sputtering target's bonding layer, and the ultrasonic flaw detection element scanning range is set so that the measurement field covers the entire bonding surface. Ultrasonic flaw detection measurement (C-scan) is performed on the bonded sputtering target. Ultrasonic waves are incident from the target material side.

[0114] The data collected is analyzed using the analysis program included with the ultrasonic flaw detector to determine the bonding rate and maximum defect area. Surface finishing is then performed through grinding and sandblasting.

[0115] Table 1 shows the results of the sputtering targets bonded in the same manner as in Example 1.

[0116] (Examples 2 to 12)

[0117] Examples 2 to 12 were conducted in the same manner as Example 1, except that after the target was placed on the bonding surface of the backing plate, the bonding layer (the contact portion, the bonding area where the target is placed) between the target and the backing plate was tapped from above over substantially the entire surface to remove air from the bonding layer. In Examples 2 to 12, the target was slid in the first direction and then in the second direction in the same manner as in Example 1. The difference between the maximum and minimum thicknesses of the sputtering target bonding layer was determined in the same manner as in Example 1 and was found to be 0.2 to 0.4 mm.

[0118] (Example 13)

[0119] In Example 13, the bonding surface of the back plate is metallized with Sn-Zn material. Sn-Zn (containing 9% Zn) is used as the bonding material. The air in the bonding layer is not knocked out. Apart from this, a sputtering target is prepared using the same method as in Example 2 to calculate the bonding rate and the maximum defect area.

[0120] (Comparative Example 1)

[0121] In Comparative Example 1, the same procedures as in Examples 2 to 12 were carried out except that the target was slid only in the first direction and was not reversely slid in the second direction.

[0122] (Comparative Example 2)

[0123] In Comparative Example 2, the target material was not slid, reversely slid, or knocked out with air. A sputtering target was produced under the conditions described in Table 1 without sliding or reversely sliding the target material.

[0124] [Table 1]

[0125]

[0126] In Table 1, the amount of bonding material is Figure 1B The amount of bonding material applied to the bonding area 30 of the back plate 3. The so-called "supplementary bonding material amount" refers to the amount of bonding material applied to the bonding area 30 of the back plate 3. Figure 1D The amount of bonding material added to the bonding area 30 of the backing plate 3 through which the target material passes. Figure 1A The type of wire 5 set in the bonding area 30 of the back plate 3 is stainless steel. The so-called "wire diameter" refers to the diameter of the wire 5. The so-called "bonding material type" refers to the material of the bonding material, and solder containing In and Sn-Zn is used. The so-called "target setting position" refers to the position of the target material. Figure 1CThe position where the target 2 is set 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 2. The so-called "air knocking" refers to the Figure 1C The end edge of the target 2 is arranged on the first end edge side of the bonding area of the backing plate, and Figure 1D At the stage when the movement (sliding) of the target 2 in the first direction D1 is completed, the upper surface of the target 2 is struck to remove the air between the target 2 and the backing plate 3. The so-called "target excess" refers to the amount of the target 2 exposed from the bonding area 30. Figure 1D ] is the distance A in the first direction D1 from the second end edge 32 of the bonding region 30 of the backing plate 3 to the first end edge 21 of the target 2. The term "bonding material replenishment" refers to whether the bonding material is replenished.

[0127] As shown in Table 1, in Examples 1 to 13, the bonding rate is above 97%, and the maximum defect area is 2000 mm 2 In Examples 1 to 13, the target material was not easily peeled off, and even after use in the sputtering apparatus, no peeling of the target material was observed.

[0128] 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 2 In Comparative Examples 1 and 2, the target material was easily peeled off.

[0129] It should be noted that the present invention is not limited to the above-described embodiment, and design changes can be made within a scope that does not depart from the gist of the present invention.

[0130] In the aforementioned embodiment, the target and the backing plate are formed in a long strip shape, but the short side and the long side of the target and the backing plate may be of the same length.

[0131] Description of Reference Numerals

[0132] 1 Sputtering target

[0133] 2 Target

[0134] 2a Sputtering surface

[0135] 21 1st edge

[0136] 22 2nd edge

[0137] 3 Back panel

[0138] 3a Main surface

[0139] 30 Joint area

[0140] 31 1st edge

[0141] 32 2nd edge

[0142] 4 Bonding materials

[0143] 6 Bonding layer

[0144] 5 lines

[0145] 10 Defective areas

[0146] D1 1st direction

[0147] D2 2nd direction

Claims

1. A sputtering target having: Back panel; a target material bonded to the bonding region of the backing plate by means of a bonding material; and a bonding layer formed by a bonding material between the backing plate and the target, in, The bonding area of the bonding portion between the target and the backing plate is 97% or more relative to the area of the bonding region. In the entire bonding region, the maximum defect area of a portion where no bonding material is present between the target and the backing plate is 2% or less relative to the entire area of the bonding region. The difference between the maximum thickness and the minimum thickness of the bonding layer is less than 0.5 mm, The target material is formed into a plate shape, The target material is made of metal or its alloy.

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

3. The sputtering target according to claim 1, wherein There are a plurality of wires between the target and the backing plate. The sputtering target according to claim 3 , wherein: The wires are arranged at intervals in a direction perpendicular to the long side direction of the target material, and the ratio of the number of wires to the length of the long side direction of the target material, that is, the number of wires / the length of the long side direction of the target material, is greater than 0.002 and less than 0.

008. The unit of the number of wires is roots, and the unit of the length of the long side direction of the target material is mm.

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