WO2020196281A1 - Method for polishing target material, method for producing target material, and method for producing recycled ingot - Google Patents

Abstract

The present invention addresses the problem of providing a method for polishing a target material, whereby it becomes possible to remove a bonding material from the target material and to reduce the clogging in a polishing material.　The method for polishing a target material according to the present invention is a method for polishing a target material separated from a sputtering target formed by bonding the target material to a support member with a bonding material, the method comprising polishing a bonding surface of the target material, i.e., a surface of the target material which has been bonded to the support member, with a polishing material which comprises a plurality of block bodies each composed of a grind stone, wherein the plurality of block bodies are arranged on a single plane in such a manner that adjacent two block bodies are separated from each other with a gap space interposed therebetween.

Description

Target material polishing method, target material manufacturing method, and recycled ingot manufacturing method

The present invention relates to a method for polishing a target material, a method for producing a target material to be treated by the polishing method, and a method for producing an ingot (hereinafter, also referred to as a recycled ingot) using the target material as a raw material obtained by the manufacturing method. ..

In a sputtering target, a target material generally composed of ceramics such as oxides, metals, or alloys and a support member such as a backing plate or backing tube composed of metals and alloys are bonded by a bonding material such as solder. It is made by bonding). By subjecting such a sputtering target to sputtering, a thin film such as a metal or an oxide can be formed on the substrate. The target material, regardless of its type, is not completely consumed by sputtering and is recovered after its use. For example, metals such as aluminum and copper can be reused as ingots (slabs, ingots) by melting and casting.

In order to reuse the recovered target material, it is necessary to remove surface deposits such as a bonding material adhering to the target material. For example, a chemical treatment such as acid treatment or a removal method by grinding is known. Conventionally, as a method for polishing and grinding a used target material, there is one described in JP-A-2002-120155 (Patent Document 1). In this method of polishing the target material, the support member is removed from the used sputtering target, and the bonding material adhering to the target material has an abrasive grain ratio of 30 to 48%, a binder ratio of 7 to 15%, and a porosity of 45. Remove with an alumina-based grindstone or diamond-based grindstone that is ~ 63%.

JP-A-2002-120155

However, in the conventional method for polishing the target material, clogging occurs in the grindstone and the abrasive material, and the clogging cannot be sufficiently reduced, and the bonding material of the target material is sufficiently removed. I can't. It is necessary to frequently replace the grindstone and the abrasive material, which takes time and effort. This is especially noticeable in target materials for large flat panel displays.

Therefore, an object of the present invention is a method for polishing a target material, which can reduce clogging of the polishing material due to the bonding material and reduce and remove impurities derived from the bonding material and the support member from the target material. It is an object of the present invention to provide a method for producing a target material to be treated, and a method for producing a recycled ingot using the target material obtained by the production method as a raw material.

In order to solve the above problems, the method for polishing the target material of the present invention is:
A method of polishing a target material separated from a sputtering target formed by joining a target material and a support member with a joining material.
The joint surface of the target material that has been joined to the support member includes a plurality of block bodies made of grindstones, and the plurality of block bodies are made on the same surface so as to be separated from adjacent block bodies via a gap. Includes polishing with an array of abrasives.

According to the method for polishing a target material of the present invention, the joint material can be removed from the target material by polishing the joint surface of the target material with an abrasive material containing a plurality of block bodies, and the joint material is removed. It is possible to reduce the clogging of the abrasive by removing the bonded material from the gap between the adjacent block bodies to the outside.

Further, in one embodiment of the method for polishing the target material, the abrasive is formed in a belt shape, and the joint surface of the target material is polished while rotating the abrasive.

According to the above embodiment, since the joint surface of the target material is polished while rotating the belt-shaped abrasive, the removed joint material can be more reliably removed to the outside.

Further, in one embodiment of the method for polishing the target material, the belt-shaped abrasive is hung around a roller, and the joint surface of the target material is pressed against the target material by using the roller. To polish.

According to the above embodiment, since the joint surface of the target material is polished while pressing the abrasive material against the target material using a roller, the joint material can be more reliably removed from the joint surface of the target material.

Further, in one embodiment of the method for polishing the target material, the roller is a rubber roller.

According to the above embodiment, since the roller is a rubber roller, the hardness of the rubber roller allows the abrasive material to be polished so as to bite into the joint surface of the target material, and the joint material can be further polished from the joint surface of the target material. It can be reliably removed.

Further, in one embodiment of the method for polishing the target material, the Vickers hardness of the target material is 150 or less.

According to the above embodiment, the joint material can be removed from the joint surface of the target material having a Vickers hardness of 150 or less.

Further, in one embodiment of the method for polishing the target material, the main component of the target material is aluminum or copper.

According to the above embodiment, the bonding material can be removed from the bonding surface of the target material composed of aluminum or copper.

Further, in one embodiment of the method of polishing the target material,
The Vickers hardness of the target material is 10 or more and 40 or less.
The surface roughness Ra of the block body of the abrasive material is 10 μm or more and 30 μm or less.

According to the above embodiment, the bonding material can be more reliably removed from the bonding surface of the target material composed of a metal or alloy having a Vickers hardness of 10 or more and 40 or less.

Further, in one embodiment of the method of polishing the target material,
The Vickers hardness of the target material is 40 or more and 120 or less.
The surface roughness Ra of the block body of the abrasive material is 12 μm or more and 50 μm or less.

According to the above embodiment, the bonding material can be more reliably removed from the bonding surface of the target material composed of a metal or alloy having a Vickers hardness of 40 or more and 120 or less.

Further, in one embodiment of the method for polishing the target material, the bonding material is a solder material containing tin, zinc, indium, lead or an alloy thereof.

Further, in one embodiment of the method for producing a target material, a method for producing a target material (or a used target material) is provided, which comprises treating the target material by the polishing method.

According to the above embodiment, it is possible to manufacture a used target material having a small amount of impurities (bonding material).

Further, one embodiment of the method for producing a recycled ingot includes producing a recycled ingot by casting the target material obtained by the manufacturing method as a raw material.

According to the above embodiment, a recycled ingot with few impurities (bonding material) can be produced.

According to the method for polishing the target material of the present invention, clogging of the abrasive material can be reduced and the bonding material can be removed from the target material.

It is explanatory drawing which shows one Embodiment of the used sputtering target of this invention. It is explanatory drawing which shows one Embodiment of the method of separating a used sputtering target material into a target material and a support member when the target material of this invention is a flat plate type. It is explanatory drawing which shows one Embodiment of the polishing method of the target material of this invention. It is a top view which shows one Embodiment of the abrasive of this invention. 4 is a cross-sectional view taken along the line XX of FIG. 4A.

Hereinafter, the present invention will be described in detail by the illustrated embodiment.

(Embodiment)
1 to 3 are explanatory views showing an embodiment of the method for polishing a target material of the present invention. As shown in FIGS. 1 to 3, this method is a method of polishing the target material 2 separated from the used sputtering target 1.

In the present invention, the "sputtering target" is formed by joining a target material and a support member with a joining material, and if it can be used for sputtering, the shape and material of the target material, the support member, etc. Is not particularly limited. When the sputtering target is a flat plate type, a flat plate backing plate can be used as the support member. When the sputtering target is cylindrical, a cylindrical backing tube can be used as the support member. Here, a cylindrical backing tube can be inserted inside the cylindrical target material, and the inner peripheral portion of the cylindrical target material and the outer peripheral portion of the backing tube can be joined by a joining material.

As shown in FIG. 1, the sputtering target 1 has a configuration in which the target material 2 and the support member 3 are joined by a joining material.

The target material 2 has a sputter surface 2a on the upper surface and a joint surface 2b on the lower surface. During the sputtering of the target material 2, the inert gas ionized by the sputtering collides with the sputtering surface 2a. The target atom contained in the target material 2 is knocked out from the sputtered surface 2a on which the ionized inert gas collides. The knocked-out atoms are deposited on a substrate arranged so as to face the sputtering surface 2a, and a thin film is formed on the substrate.

The target material 2 can be mainly composed of metal. For example, the target material 2 includes metals such as aluminum, copper, chromium, iron, tantalum, titanium, zirconium, tungsten, molybdenum, niobium, silver, cobalt, ruthenium, platinum, palladium, gold, rhodium, indium and nickel, and the like. It can be made from a material selected from the group consisting of alloys containing metals selected from the group. The material constituting the target material 2 is not limited to these.

The Vickers hardness of the target material 2 is preferably 150 or less, more preferably 10 or more and 100 or less, and even more preferably 12 or more and 90 or less. When the polishing method of the present embodiment is applied to the target material 2 having such a Vickers hardness range, the bonding material or the like can be removed more preferably. The Vickers hardness can be confirmed by the Vickers hardness test (JIS Z 2244: 2003).

The main component of the target material 2 is preferably aluminum (purity 99.99% (4N) or higher, preferably purity 99.999% (5N) or higher) or copper (purity 99.99% (4N) or higher). .. When the main component of the target material 2 is aluminum, the Vickers hardness of the target material 2 is preferably 10 or more and 40 or less, more preferably 12 or more and 35 or less, and further preferably 14 or more and 30 or less. When the main component of the target material 2 is copper, the Vickers hardness of the target material 2 is preferably 40 or more and 120 or less, more preferably 60 or more and 100 or less, and further preferably 80 or more and 95 or less. There are no particular restrictions on the dimensions, shape and structure of the target material 2. As the target material 2, a flat plate type or a cylindrical type can be used.

When the target material 2 is a flat plate type, the dimensions of the target material 2 in the longitudinal direction are, for example, 500 mm or more and 4000 mm or less, preferably 1000 mm or more and 3200 mm or less, and more preferably 1200 mm or more and 2700 mm or less. The dimensions in the width direction (direction perpendicular to the longitudinal direction) are, for example, 50 mm or more and 1200 mm or less, preferably 150 mm or more and 750 mm or less, and more preferably 170 mm or more and 300 mm or less. The target material 2 may be formed to be long, or the short side and the long side may have the same length. The thickness is, for example, 5 mm or more and 35 mm or less, preferably 10 mm or more and 30 mm or less, and more preferably 12 mm or more and 25 mm or less.

When the target material 2 has a cylindrical shape, the dimensions of the target material 2 in the longitudinal direction are, for example, 1000 mm or more and 5000 mm or less, preferably 1500 mm or more and 4500 mm or less, more preferably 2000 mm or more and 4000 mm or less, further preferably 2200 mm or more and 3500 mm or less. More preferably, it is 2500 mm or more and 3000 mm or less. The outer diameter of the target material 2 is 75 mm or more and 400 mm or less, preferably 100 mm or more and 350 mm or less, more preferably 120 mm or more and 300 mm or less, still more preferably 140 mm or more and 250 mm or less, still more preferably 150 mm or more and 200 mm or less. The inner diameter of the target material 2 is 50 mm or more and 250 mm or less, preferably 70 mm or more and 200 mm or less, more preferably 80 mm or more and 180 mm or less, still more preferably 100 mm or more and 160 mm or less, and even more preferably 110 mm or more and 150 mm or less. In the present invention, for example, even a target material 2 for a large flat panel display can be easily processed.

When the support member 3 is a backing plate, the dimensions, shape and structure of the backing plate are not particularly limited as long as they are plate-shaped in which the target material 2 can be arranged. The length of the backing plate in the long side direction is, for example, 700 mm or more and 4500 mm or less, preferably 1200 mm or more and 4000 mm or less, more preferably 1500 mm or more and 3500 mm or less, and the length of the backing plate in the short side direction is, for example, 100 mm or more. It is 1500 mm or less, preferably 180 mm or more and 1000 mm or less, and more preferably 200 mm or more and 350 mm or less. The backing plate may be formed to be long, or the short side and the long side may have the same length. The backing plate is made of a conductive material and is a metal selected from the group consisting of copper, chromium, aluminum, titanium, tungsten, molybdenum, tantalum, niobium, iron, cobalt and nickel or a metal selected from the above group. It is composed of an alloy containing at least one kind, and is preferably copper (oxygen-free copper), chromium copper alloy, or aluminum alloy. On the other hand, when the support member is a backing tube, the size of the backing tube is usually longer than that of the cylindrical target material because it is inserted and joined inside the cylindrical target material, and the outer diameter of the backing tube is the cylindrical target. It is preferably slightly smaller than the inner diameter of the material. The constituent metal or alloy is the same as in the case of the backing plate described above, but among them, stainless steel (SUS), titanium, titanium alloy and the like are preferable.

The support member 3 has a joint surface 3a on the upper surface. The joint surface 3a of the support member 3 is joined to the joint surface 2b of the target material 2 via the joint material. The joining material includes, for example, a solder material, a brazing material, and the like.

The solder material is a material containing a metal or alloy having a low melting point (for example, 723 K or less), and the solder material is, for example, indium (In), tin (Sn), zinc (Zn), lead (Pb), silver. Examples thereof include a metal selected from the group consisting of (Ag), copper (Cu), bismuth (Bi), cadmium (Cd) and antimony (Sb), or an alloy containing at least one metal selected from the group. The solder material is preferably a solder containing an alloy containing at least one metal selected from the group consisting of tin, zinc, indium, lead, or Sn, Zn, In, and Pb, and more specifically. Specifically, In, In-Sn, Sn-Zn, Sn-Zn-In, In-Ag, Sn-Pb-Ag, Sn-Bi, Sn-Ag-Cu, Pb-Sn, Pb-Ag, Zn- Examples thereof include Cd, Pb-Sn-Sb, Pb-Sn-Cd, Pb-Sn-In, Bi-Sn-Sb and the like.

As the brazing material, the target material 2 and the support member 3 can be joined, and any metal or alloy having a melting point lower than that of the target material 2 and the support member 3 can be used without particular limitation.

Generally, solder materials such as In and In alloys and Sn and Sn alloys, which have low melting points, are used as the bonding material, but these solder materials are soft and easily penetrate into the unevenness of the surface of the abrasive or the grindstone or adhere to the surface. Therefore, it is easy to cause clogging of the abrasive and the grindstone. When the polishing method of the present embodiment is applied when the solder material as described above is used as the bonding material, a more remarkable effect can be obtained and the bonding material or the like can be removed more preferably.

For example, the solder material can form a diffusion layer (alloy layer) with the metal contained in the target material 2 at the joint surface with the target material 2 by heating, thereby joining the target material 2 and the solder material. it can. Alternatively, the bonding material may also form a diffusion layer (alloy layer) with the metal contained in the support member 3 on the bonding surface with the support member 3, thereby joining the support member 3 and the solder material. it can. Therefore, by using such a solder material, a solder layer can be formed as a bonding layer between the target material 2 and the support member 3, and the target material 2 and the support member 3 can be bonded to each other.

A metallized layer may be formed on the joint surface 2b of the target material 2 and the joint surface 3a of the support member 3. In general, simply placing a solder material on the target material 2 and the support member 3 and melting the solder material may not provide sufficient bonding strength due to the influence of the oxide film that may exist on the surface of the target material 2 and the support member 3. is there. Therefore, first, a metallized layer may be provided in order to improve the wettability of the solder material with respect to their surfaces. In this case, the joint layer formed between the target material 2 and the support member 3 is formed on the solder layer, the metallized layer formed on the joint surface 2b of the target material 2, and the joint surface 3a of the support member 3. It has a metallized layer.

"Metallizing" is a treatment method that can be generally used to form a metal film on a non-metal surface. The metallized layer is formed on the target material 2 and the support member 3 by using, for example, a metallizing solder material when the target material 2 and the support member 3 have an oxide film. In the metallized layer, for example, an ultrasonic soldering iron is used to destroy the oxide film of the target material 2 and the support member 3 by the vibration energy (cavitation effect) of ultrasonic waves, and the oxygen atoms in the oxide film are heated by heating. At the same time, it can be formed by chemically bonding the metal atoms contained in the solder material for metallization and the metal atoms contained in the target material 2 and the support member 3.

The solder that can be used for metallization is, for example, a metal selected from the group consisting of In, Sn, Zn, Pb, Ag, Cu, Bi, Cd and Sb, or at least one metal selected from the group. It is a material containing an alloy containing, and more specifically, In, In-Sn, Sn-Zn, Sn-Zn-In, In-Ag, Sn-Pb-Ag, Sn-Bi, Sn-Ag-Cu. , Pb-Sn, Pb-Ag, Zn-Cd, Pb-Sn-Sb, Pb-Sn-Cd, Pb-Sn-In, Bi-Sn-Sb and the like. A material having a high affinity with the target material 2 or the support member 3 may be appropriately selected.

The metallized layer can also be bonded to the solder layer, and is located between the target material 2 and the solder layer layer or between the support member 3 and the solder layer, respectively, and is located between the target material 2 and the bonding layer and the support member 3. And can play a role of firmly bonding the bonding layer.

In the present specification, the bonding layer is not only a layer composed of bonding materials such as solder and brazing material, but also a metallized layer formed on the bonding surface 2b of the target material 2 and the bonding surface of the support member 3. It also includes the case of a layer containing at least one of the metallized layers formed on 3a.

The thickness of the solder layer can be, for example, 50 μm or more and 500 μm or less when the support member 3 is a flat plate type, and can be, for example, 250 μm or more and 1500 μm or less when the support member 3 is a cylindrical type. The thickness of the metallized layer may be in the range of, for example, 1 μm or more and 100 μm or less when the support member 3 is both a flat plate type and a cylindrical type.

As shown in FIG. 1, the sputtered surface 2a of the target material 2 is sputtered to use the sputtering target 1, and then the target material 2 is separated (or peeled off) from the used sputtering target 1 as shown in FIG. To do. The method of separating the target material 2 from the support member 3 is not particularly limited. For example, heat (for example, 180 ° C. or higher and 300 ° C. or lower) is applied to the joint layer to soften or melt the joint layer, and if necessary, physically break the joint layer to separate the target material 2 from the sputtering target 1. can do.

When the target material 2 is a flat plate type, the surface (joint surface 2b, sometimes referred to as "joint surface") bonded to the backing plate in the target material 2 after separation includes the above-mentioned metallized layer. , At least a part of the bonding layer is attached and remains. In some cases, not only the bonding layer but also impurities derived from the backing plate may be diffused and remain on the surface of the bonding layer and the target material 2 on the bonding surface side.

Preferably, before polishing the target material 2, the joint layer adhering to the joint surface 2b after separation is scraped off as much as possible in advance using, for example, a spatula (for example, a spatula made of silicone). It is difficult to completely remove the bonding material adhering to the bonding surface 2b after separation by scraping in advance with a spatula or the like, and in particular, the metallized layer firmly bonded to the target material 2 cannot be removed. In addition, the bonding material may adhere and remain on the sputtered surface 2a and the side surface of the target material 2. The causes are, for example, that the bonded material melted during the separation of the target material 2 adheres to the sputtered surface 2a and the side surface, and that the separated used target materials 2 are stacked and stored on each other, so that the bonded surface 2b And the sputtered surface 2a and the side surface come into contact with each other, and the bonding material of the bonding surface 2b adheres to the sputtered surface 2a and the side surface. Therefore, the polishing method of the present invention may be applied to the sputtered surface and the side surface.

When the target material is cylindrical, the cylindrical target material can be joined to the outer peripheral portion of the cylindrical backing tube using a joining material. Therefore, as in the case of the flat plate type target material described above, the joint material adheres to the joint surface (inner peripheral portion) of the target material after separation, and it is more difficult to remove the joint material than the flat plate type target. is there. Further, as in the case of the flat plate type target material, the bonding material may adhere and remain on the sputtering surface of the cylindrical target material. Furthermore, components derived from the backing tube may also be mixed as impurities. Therefore, even in the case of a cylindrical target material, the polishing method can be applied to the inner peripheral portion which is the joint surface of the target material after separation and the outer peripheral portion which is the sputtering surface. When processing the inner peripheral portion which is the joint surface of the target material, for example, the circumference of the cylinder of the target material is divided into two equal parts (that is, the cylindrical target parallel to the longitudinal direction of the cylinder). It is preferable to cut the material (so as to divide it into two equal parts) and process it so that the inner peripheral portion which is the joint surface is exposed before applying the polishing method.

The presence of the bonding material in the target material after separation can be confirmed by, for example, Energy Dispersive X-ray Fluorescence Analysis (EDXRF). Further, when the metal element diffuses from the support member to the target material, the metal element can also be confirmed by EDXRF in the same manner. In addition, wavelength dispersive fluorescent X-ray analysis (WDXRF: Wavelength Dispersive X-ray Fluorescence Analysis), electron beam probe micro analysis (EPMA: Electron Probe Micro Analysis), Auger electron spectroscopy (AES: Auger Electron Spectroscopy), X Line photoelectric spectroscopy (XPS: X-ray Photoelectron Spectroscopy), time-of-flight secondary ion mass spectrometry (TOF-SIMS: Time-of-Flight Secondary Ion Mass Spectrometry), laser irradiation inductively coupled plasma mass spectrometry (LA-) Even with analysis methods such as ICP-MS: Laser Ablation Inductively Coupled Plasma Mass Spectrometry) and X-ray Diffraction Analysis (XRD), impurities derived from the bonding material and support member can be confirmed. Confirmation by EDXRF or WDXRF is preferable because of its simplicity and wide analysis range.

In the subsequent recycling process, an ingot (hereinafter, may be referred to as “slab” or “ingot”) is produced by melting and casting the separated target material to which the bonding material is attached as it is, and this ingot is produced. When the target material is manufactured again from the above, impurities derived from the components of the adhered bonding material are mixed in the target material. Further, when the metal element diffuses from the support member to the target material and is mixed as an impurity, the metal element may be mixed as an impurity in the ingot.

At least, the target material can be cleaned by polishing the joint surface 2b where the target material 2 and the support member 3 in the target material are joined.

FIG. 4A is a plan view of the abrasive 13 and FIG. 4B is a cross-sectional view taken along the line XX of FIG. 4A. As shown in FIGS. 4A and 4B, the abrasive 13 has a sheet body 20 and a plurality of block bodies 21 provided on one surface of the sheet body 20. The sheet body 20 is made of rubber, for example, and is formed in a belt shape. The plurality of block bodies 21 are arranged on one surface of the sheet body 20 which is the same surface.

In FIG. 4A, the block body 21 is formed in a parallel quadrilateral shape in a plan view, but the shape is not particularly limited and may be a rectangle, a square, a rhombus, a perfect circle, an ellipse, or the like. It may be a combination of shapes. Further, the block body 21 may have a shape such as a hemisphere, a cone, or a pyramid that is convex with respect to the surface to be processed, but faces the surface to be processed in order to maintain the polishing force on the solder material. It is preferable that the surface to be processed is a flat surface, and from the viewpoint that the block body 21 can be densely arranged, it is a parallelogram, a rectangle, a square, or a rhombus when viewed from the side of the surface to be processed. Is more preferable. The size of the polished surface of the block body 21 is 5 mm or more and 30 mm or less on one side or diameter, preferably 7 mm or more and 25 mm or less, more preferably 10 mm or more and 20 mm or less, and further preferably 12 mm or more and 18 mm or less. When the size of the polished surface of the block body 21 is within the above range, the polishing force for the solder material can be maintained, and clogging of the polished surface of the abrasive material can be prevented.
The plurality of block bodies 21 are preferably arranged in a staggered pattern along the polishing direction indicated by the arrow R in FIG. 4A. As a result, the block body 21 hits the surface to be processed without a gap, and the solder material can be efficiently removed. Further, the plurality of block bodies 21 are preferably arranged in a straight line along the arrow A direction intersecting the arrow R direction at a predetermined angle θ. The predetermined angle θ is 10 ° or more and less than 90 °, preferably 30 ° or more and 85 ° or less, more preferably 45 ° or more and 80 ° or less, still more preferably 60 ° or more and 75 ° or less, and the plurality of block bodies 21 have a plurality of block bodies 21. It is preferable that the array is linearly inclined with respect to the direction orthogonal to the arrow R direction. By arranging the block body 21 so as to have the predetermined angle θ, it is possible to prevent the block body 21 from being chipped or clogged by the solder material.
The adjacent block bodies 21 are separated from each other through the gap 23. The block body 21 is made of a grindstone. The grindstone is made of, for example, a mixture of abrasive grains such as silicon carbide, chromium oxide, zirconium oxide, cerium oxide, zircon, diamond, boron nitride, and alumina bonded with a binder made of resin. Examples of the binder include epoxy resin, polyester resin, phenol resin, melamine resin, acrylic resin, urea resin, polyvinyl alcohol resin, polyvinyl acetal resin and the like. The abrasive grain composition, abrasive grain size, and binder type can be selected according to the composition of the target material and the solder material, and a plurality of types may be selected. In order to reduce contamination of the target material by abrasive grains, it is preferable to select an abrasive material having a composition close to that of the target material 2.
From the viewpoint of efficiently removing impurities derived from the bonding material and the support member, the height of the block body 21 is preferably uniform, and the average height of the block body 21 is, for example, 0.5 mm or more, preferably 1 mm. The above is more preferably 1.5 mm or more, further preferably 2 mm or more, 10 mm or less, preferably 8 mm or less, more preferably 6 mm or less, still more preferably 5 mm or less, and particularly preferably 4 mm or less. When the average height of the block body 21 is not less than the lower limit value, the life of the abrasive material is extended and the frequency of replacing the abrasive material can be reduced. When the average height is not more than the upper limit value, even at the initial stage of use of the abrasive material. Good ground contact with the bonding material adhering to the target material 2, stable polishing is possible without vibration during polishing, and impurities derived from the bonding material and support member are efficiently removed. Can be done.
When the average height of the block body 21 is equal to or less than the upper limit value, the average separation distance of the block body 21 (the width of the gap 23 in FIG. 4B, which is the XX cross section of FIG. 4A) from the viewpoint of efficiently releasing the bonding material. ) Is, for example, 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.3 mm or more, still more preferably 0.4 mm or more, and 1 mm or less, preferably 0.8 mm or less, more preferably 0. It is 7 mm or less, more preferably 0.6 mm or less. Here, the XX cross section of FIG. 4A is a cross section of the block bodies 21 adjacent to each other in the direction intersecting the arrow A direction, and in other words, the blocks in the first row arranged linearly in the arrow A direction. It is a cross section intersecting the body 21 and the block body 21 in the second row adjacent to the block body 21 in the first row.
When the average separation distance (width of the gap 23) of the block body 21 is equal to or greater than the lower limit value, even abrasive scraps containing soft and sticky metals and alloys such as solder are efficiently discharged from the gap 23. It is possible to prevent clogging of the abrasive material. When the average separation distance (width of the gap 23) of the block body 21 is equal to or less than the upper limit value, the risk of the block body 21 detaching from the sheet body 20 can be reduced. In FIG. 4B, the plurality of block bodies 21 are completely separated from each other, but as long as they do not affect clogging, the structure is such that they are connected in the vicinity immediately above the sheet body 20, that is, in the lower part of the block body 21. You may. This makes it possible to facilitate the bonding process between the block body 21 and the sheet body 20. The peripheral edge of the upper surface of the block body 21 is 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.5 mm or more, still more preferably 0.7 mm or more, still 3 mm or less, more preferably 2 mm or less, still more preferably. It is preferably C-chamfered or R-chamfered within a range of 1.5 mm or less. When the peripheral edge of the block body 21 is chamfered in the above range, it is possible to prevent the block body 21 from being chipped and to prevent the accumulation of solder on the corners caused by the corners of the block 21 sticking into the solder layer. Can be done.

The surface roughness of the block body 21 of the abrasive material 13 on the polished surface, for example, the arithmetic mean roughness Ra, can be adjusted by the size of the abrasive grains and the blending amount of the abrasive grains, and is appropriately selected according to the Vickers hardness of the target material 2. Will be done. For example, in a target material made of a metal or alloy having a Vickers hardness of 150 or less, the surface roughness Ra on the polished surface of the block body 21 is 3 μm or more, preferably 5 μm or more, more preferably 9 μm or more, still more preferably 10 μm or more. It is particularly preferably 15 μm or more, and 150 μm or less, preferably 100 μm or less, more preferably 50 μm or less, and further preferably 35 μm or less. More specifically, in a target material made of a metal or alloy having a Vickers hardness of 10 or more and 40 or less or a target material whose main component is aluminum, the surface roughness Ra on the polished surface of the block body 21 is 3 μm or more and 150 μm or less. It is preferably 3 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm, further preferably 7 μm or more and 30 μm or less, still more preferably 10 μm or more and 27 μm or less, and particularly preferably 15 μm or more and 25 μm or less. Further, in a target material made of a metal or alloy having a Vickers hardness of 40 or more and 120 or less or a target material whose main component is copper, the surface roughness Ra on the polished surface of the block body 21 is 5 μm or more and 150 μm or less, preferably 8 μm or more. It is 120 μm or less, more preferably 10 μm or more and 100 μm, further preferably 12 μm or more and 50 μm or less, still more preferably 12 μm or more and 45 μm or less, and particularly preferably 15 μm or more and 40 μm or less. When the surface roughness Ra on the polished surface of the block body 21 of the abrasive material 13 is at least the above lower limit value, it is possible to have sufficient polishing power with respect to the solder material and the target material 2, and the surface roughness Ra is said. If it is less than the upper limit, it is possible to reduce the risk that large grooves or dents are generated on the treated surface of the target material 2, polishing chips are caught in the grooves or dents, or the solder material is pushed into the treated surface of the target material 2. , It is possible to efficiently remove impurities derived from the solder material and the support member. In order to remove impurities derived from the solder material and the support member from the used target material 2, not only the clogging due to the soft and sticky metal or alloy such as the bonding material is reduced, but also the base of the bonding layer is used. It is preferable to adjust the surface roughness of the polishing material 13 on the polished surface of the block body 21 according to the Vickers hardness of the target material.

The operation method of the abrasive is not particularly limited. Specifically, those skilled in the art will know that the block body 21 on the surface of the abrasive material can be polished while preferably adhering to the target surface, for example, the joint surface 2b of the target material 2. Any method may be used, but it is preferable to use a polishing apparatus to which the abrasive is attached. For example, portable electric tools such as orbital sanders, delta sanders, random sanders, disc grinders, belt sanders, straight grinders, and electric polishers on the market, air tools, and surface grinders (for example, Kuroda Seiko Co., Ltd. and Okamoto Co., Ltd.) Large-scale installation-type devices such as a machine tool manufacturing machine) and a deburring machine (for example, manufactured by Esterlink Co., Ltd.) can be used. Further, the polishing may be repeated a plurality of times, preferably once or more and 10 times or less, and more preferably 2 times or more and 5 times or less at the same place.

The direction of movement of the abrasive material attached to the polishing device is not particularly limited. Specifically, a linear reciprocating motion in the horizontal direction with respect to the surface to be processed, a rotational motion in which the rotation direction is horizontal to the surface to be processed (the axis of rotation is perpendicular to the surface to be processed), Examples thereof include rotational motion in which the rotation direction is perpendicular to the surface to be processed (the axis of rotation is horizontal to the surface to be processed). In order for the abrasive material of the present invention to be more effective, it is preferable to use a polishing device in which the attached abrasive material rotates, and the rotation direction is perpendicular to the surface to be processed (rotational axis). Is more preferable to a polishing device that performs (horizontally to the surface to be processed).

FIG. 3 shows an embodiment of the method for polishing a target material of the present invention. As a polishing device, a polishing tool 10, that is, a belt sander (a polishing device that performs a rotational motion in which the rotation direction is perpendicular to the surface to be processed). This is an example using. The polishing tool 10 has a main body portion 11 and a polishing portion 12 attached to the main body portion 11. The main body portion 11 has a grip portion gripped by an operator and a motor for driving the polishing portion 12. The polishing unit 12 has a first roller 15 on the driving side, a second roller 16 on the driven side, and a belt-shaped polishing material 13 hung around the first roller 15 and the second roller 16. The first roller 15 is connected to the motor. Then, by driving the motor, the first roller 15 rotates, and the abrasive 13 rotates in the direction of the arrow R. That is, the polishing direction is the direction of the arrow R.

As shown in FIG. 3, when the joint surface 2b of the target material 2 is polished by the polishing tool 10, the polishing material 13 is pushed against the target material 2 by using at least the first roller 15 of the first roller 15 and the second roller 16. The joint surface 2b of the target material 2 is polished by the abrasive material 13 while rotating the abutting abrasive material 13. At this time, the polishing tool 10 is arranged so that the surface of the block body 21 (the surface facing the surface in contact with the sheet body 20) of the polishing material 13 is in contact with the joint surface 2b of the target material 2. Attached to. The operator polishes the entire surface of the joint surface 2b of the target material 2 while moving the polishing tool 10 along the joint surface 2b of the target material 2.

According to the polishing method of the target material 2, the bonding material can be removed from the target material 2 by polishing the bonding surface 2b of the target material 2 with the polishing material 13 including the plurality of block bodies 21. Further, the removed bonding material can be removed to the outside from the gap 23 between the adjacent block bodies 21 to reduce the clogging of the abrasive material 13.

Further, since the joint surface 2b of the target material 2 is polished while rotating the belt-shaped abrasive material 13, the removed joint material can be more reliably removed to the outside.

Further, since the joint surface 2b of the target material 2 is polished while pressing the abrasive 13 against the target material 2 by using the first roller 15, the joint material can be more reliably removed from the joint surface 2b of the target material 2. it can.

The first roller 15 can be made of resin or metal such as sponge or rubber, but is preferably made of resin, and more preferably a rubber roller. According to this, due to the hardness and flexibility of the rubber roller, the abrasive material 13 and the joint surface 2b of the target material 2 can be brought into close contact with each other, and further, the target material 2 can be polished while applying a greater load. The bonding material can be removed more reliably from the bonding surface 2b of the above.

After the bonding material on the target material 2 has been sufficiently removed, the risk of clogging of the abrasive material is significantly reduced, so that a finish polishing process using a known abrasive material may be performed. For example, for the purpose of improving contamination by abrasive grains, finish polishing may be performed with an abrasive material having abrasive grains having a composition close to that of the target material 2.

According to the method for polishing the target material of the present embodiment, impurities derived from the bonding material and the support member 3 forming the bonding layer (including the metallized layer if present) are easily and sufficiently removed from the used target material 2. be able to. In the present specification, "sufficiently removing" means that the amount of each element detected by EDXRF measurement on the joint surface 2b where the target material 2 and the support member 3 are joined is preferably 0.5 wt% or less. Is 0.2 wt% or less, more preferably 0.1 wt% or less, the amount of elements contained in impurities derived from the bonding material (including the metallized layer if present) constituting the bonding layer, and the amount derived from the support member 3. It means that the amount of elements contained in the impurities is removed.

<Manufacturing method of target material (or used target material)>
The method for producing a target material (or used target material) according to one embodiment of the present invention includes treating the target material by the method for polishing the target material according to the above-described embodiment. The target material subjected to such treatment can be used in the production of recycled ingots described later. The method for producing the target material (or used target material) may include not only the treatment by the above-mentioned polishing method for the target material but also other treatments. For example, it may include a process for removing polishing debris adhering to the used target material after polishing (for example, blowing high-pressure air or cleaning with running water). By removing the polishing debris, it is possible to prevent problems such as foreign matter contamination caused by the polishing debris adhering to the raw material when melting and casting the used target material after cleaning as a raw material.

<Manufacturing method of recycled ingot>
In the method for producing a recycled ingot according to one embodiment of the present invention, the target material washed by the method for polishing the target material may be cast as a raw material to produce a recycled ingot. As a result, a recycled ingot with few impurities (bonding material) can be produced. The recycled ingot is also called a slab or an ingot, and the target material 2 can be produced again from this ingot.

As a method for producing recycled ingots, a method known to those skilled in the art may be used. For example, it can be manufactured through the steps of melting and casting. As a melting method, the washed target material may be melted in the air or vacuum in an electric furnace or a combustion furnace. As the casting method, a continuous casting method, a semi-continuous casting method, a mold casting method, a precision casting method, a hot top casting method, a gravity casting method and the like can be adopted. In addition, degassing treatment and inclusion removal treatment may be performed between the melting and casting steps.

The manufacturing conditions of the recycled ingot, especially the temperature, may be appropriately determined according to the metal mainly contained in the target material. For example, when the metal contained in the target material as a main component is aluminum, first, the target material washed by the method of the above-described embodiment is subjected to vacuum (for example, 0.03 Torr) or air at 670 ° C. or higher at 1200 ° C. or higher. It is dissolved in a crucible such as carbon or alumina at ° C. or lower, preferably 750 ° C. or higher and 850 ° C. or lower. Then, if necessary, the recycled ingot can be produced by stirring in the air to remove the dross and then cooling in the air.

For example, when the metal contained in the target material as the main component is copper, the target material after cleaning is placed under vacuum (for example, 0.03 Torr) or in the atmosphere at 1100 ° C. or higher and 1500 ° C. or lower, preferably 1150 ° C. or higher and 1200 ° C. In the following, recycled ingots can be produced by dissolving in a crucible such as carbon or alumina, stirring in the air as necessary to remove dross, and then cooling in the air.

In the production of the recycled ingot, it may be produced only with the target material washed by the method of the above-described embodiment, or a mixture of the original raw material metal and the cleaned target material may be used. When the raw material metal and the target material after cleaning are mixed, the mixing ratio of the target material after cleaning can be usually 20% by mass or more. From the viewpoint that the ratio of the raw material cost to the manufacturing cost can be suppressed, it is preferably 50% by mass or more.

<Recycled ingot>
Since the recycled ingot of the present embodiment is manufactured by casting using the target material washed by the method of the above-described embodiment as a raw material, as described above, it is derived from the bonding material and the support member constituting the bonding layer. The impurities are sufficiently removed, that is, they are substantially free of the elements contained in the impurities derived from them and have substantially the same composition as the original (unused) target material. Therefore, from such recycled ingots, a target material having substantially the same composition as the original target material can be produced again.

In the present specification, "having substantially the same composition as the original (unused) target material" means that the main component metal is the same and is equivalent to the impurities originally contained in the original target material. It means that it can contain an amount of impurities. For example, the total amount of impurities derived from the bonding material and the supporting member constituting the bonding layer and the metallized layer is less than 10 ppm, preferably 0.1 ppm or more and 8 ppm or less, more preferably 0.1 ppm or more and 6 ppm or less, based on the mass. It is preferably 0.1 ppm or more and 5 ppm or less, and even more preferably 0.1 ppm or more and 4 ppm or less, and the total amount of impurities (that is, the amount of impurities originally contained in the original target material) is bonded. The sum of the total amounts of impurities derived from the material and the support member) is less than 50 ppm, preferably 0.1 ppm or more and 20 ppm or less, more preferably 0.1 ppm or more and 10 ppm or less, still more preferably 8 ppm or less (or less than 8 ppm), and even more. The case where it is preferably 0.1 ppm or more and 8 ppm or less can be mentioned.

The impurities originally contained in the original target material and the amount thereof may depend on the type of metal contained as the main component in the target material and the manufacturing method of the original target material. In addition, the recycled ingot may be used for applications other than the target material. For example, it can be used as a raw material for products requiring high purity such as aluminum electrolytic capacitors, hard disk substrates, corrosion resistant materials, and high-purity alumina.

For example, when the target material contains aluminum as a main component, the total amount of impurities derived from the bonding material and the support member constituting the bonding layer contained in the recycled ingot of the present embodiment is less than 10 ppm on a mass basis. It is preferably 0.1 ppm or more and 8 ppm or less, more preferably 0.1 ppm or more and 6 ppm or less, still more preferably 0.1 ppm or more and 5 ppm or less, still more preferably 0.1 ppm or more and 4 ppm or less, and particularly preferably 0.3 ppm or more and 2 ppm. It is as follows. For example, when the total amount of Cu, In, Sn, and Zn is within the above range, the crystal grains of the recycled ingot can be refined without causing a decrease in the conductivity of the recycled ingot. As a result, the target material produced from the recycled ingot also has fine crystal grains, so that a target material having excellent sputtering characteristics can be produced. Further, when Cu, In, Sn, or Zn having an atomic weight larger than that of aluminum is contained in the above range, the electromigration resistance of the aluminum thin film produced by sputtering the target material produced through the recycled ingot is increased. You can also do it.

Since the amount of impurities derived from the bonding material and the support member contained in the recycled ingot of the present embodiment is extremely small, it is measured by using glow discharge mass spectrometry (GDMS). Specifically, in the present specification, the amount of such impurities is an amount measured using VG9000 manufactured by VG Elemental. The lower limit of quantification of GDMS differs depending on the main element of the target material and the element to be detected. For example, when the metal contained as the main component of the target material is aluminum, it is usually 0.001 ppm or more and 0.1 ppm or less on a mass basis. Yes, for example, In is 0.01 ppm.

Although it depends on the application, for example, it is known that an aluminum target material for a flat display can usually contain impurities of 50 ppm or less, preferably 0.1 ppm or more and 20 ppm or less, and more preferably 0.1 ppm or more and 10 ppm or less on a mass basis. Has been done. Therefore, if the amount of impurities in the recycled ingot of the present embodiment is as described above, there is no particular problem in sputtering.

Further, in the present invention, since the target material is cleaned by polishing, the abrasive grains of the abrasive material can be intentionally left in the target material. By polishing the target material with an abrasive that has abrasive grains with a composition different from that of the main component of the target material, the target material has abrasive grains that become trace amounts of additive elements attached to the surface when the target material is melted. Can be manufactured. The target is a high-purity metal, preferably aluminum with a purity of 99.99% (4N) or higher, more preferably 99.999% (5N) or higher, or copper with a purity of 99.99% (4N) or higher. In this case, when a recycled ingot is obtained from the target material after cleaning, a very small amount of additive elements derived from abrasive grains contained in the target material change the crystal grain size of the recycled ingot without deteriorating the conductivity of the pure metal. It can be miniaturized, and by extension, the crystal grains of the target material produced from recycled ingots can be miniaturized, and a target material having excellent sputtering characteristics can be obtained. From the viewpoint of preventing deterioration of the conductivity of the recycled ingot and facilitating the miniaturization of the crystal grain size of the recycled ingot, the content of the abrasive grain-derived element contained in the recycled ingot is preferably 0.5 ppm. It is more than 10 ppm, more preferably 1 ppm or more and less than 10 pp, still more preferably 2 ppm or more and 8 ppm or less, and particularly preferably 2.5 ppm or more and 6 ppm or less. For example, when the target material is aluminum having a purity of 99.999% (5N) or more and the element derived from the abrasive grains of the abrasive is Si, a recycled ingot of aluminum containing a trace amount of Si can be obtained. The aluminum thin film formed on a silicon wafer or glass substrate by sputtering the target material produced from the recycled ingot suppresses the diffusion of Si from the substrate to the thin film, and the characteristics of the aluminum thin film due to excessive diffusion of Si. Can be prevented from decreasing.
Further, from the viewpoint of forming a metal thin film having excellent characteristics, particularly an aluminum thin film, the recycled ingot has a total content of Cu, In, Sn and Zn of 0.1 ppm or more and 8 ppm or less, and a Si content. Is preferably 2 ppm or more and 8 ppm or less.

As described above, according to the present invention, the used target material can be easily and sufficiently cleaned, and the cleaned target material does not substantially contain impurities derived from the bonding material and the support member, and thus is recycled. The ingot can be manufactured and the target material can be easily recycled.

The present invention is not limited to the above-described embodiment, and the design can be changed without departing from the gist of the present invention.

In the above embodiment, the joint surface of the target material is polished while rotating the abrasive material in a belt shape, but the joint surface of the target material is polished while the abrasive material is made flat and the abrasive material is moved in the horizontal direction. It may be polished. That is, the abrasive material may include a plurality of block bodies made of a grindstone, and the plurality of block bodies may be arranged on the same surface so that adjacent block bodies are separated from each other through a gap.

(Example 1)
By heating (280 ° C.) the bonding layer of the used sputtering target, the sputtering target was separated into a target material and a support member (backing plate).

In addition, the sputtering target is a flat plate type target material made of aluminum (purity: 99.999%, Vickers hardness: 16, dimensions: 2000 mm × 200 mm × 15 mm) and a support member made of oxygen-free copper (purity: 99.999%, Vickers hardness: 16, dimensions: 2000 mm × 200 mm × 15 mm) before use. Purity: 99.99%, dimensions: 2300 mm x 250 mm x 15 mm) are joined with In solder material (thickness of solder layer: 350 μm) (Sn-Zn-In solder material is used for metallizing the target material). It will be done.

Furthermore, the solder material adhering to the joint surface of the separated target material was scraped off with a silicone spatula to remove the solder material as much as possible. After separation from the sputtering target, the target material was cut to a size of about 200 mm × 100 mm × 15 mm.

A block body (JIS R 6001-1: 2017) having a parallel quadrilateral shape (in a plan view) with a surface roughness Ra of the polished surface of 20 μm, an average height of 3 mm, an average length of the long side of 16 mm, and an average length of the short side of 14 mm. A resinoid grindstone in which silicon carbide having a particle size corresponding to F120 in the above is bonded with a phenol resin) so that the average separation distance is 0.5 mm and the inclination is 72 ° with respect to the polishing direction (rotation direction of the belt sander). An abrasive material adhered to a cloth for polishing cloth (cotton-polyester blend cloth, resin cured product, carbon black mixture) with a mixed rubber was prepared. The corner portion (peripheral portion) of the block body had a 1.25 mmC chamfered shape, and the size of the abrasive material was 60 mm × 260 mm. After fixing both ends of the abrasive material to form a belt, the belt sander (manufactured by Office Mine Co., Ltd., RMB-E) and the contact wheel (roller) are sponge contact M (φ50 mm x width) manufactured by Office Mine Co., Ltd. 60 mm)), and the entire surface of the joint surface of the cut target material was evenly polished for 30 seconds (processing speed 400 cm ² / min). The surface roughness Ra (arithmetic mean roughness) of the abrasive material is based on JIS B0601: 2001, and is a small surface roughness meter surf test SJ-301 manufactured by Mitutoyo Co., Ltd. (Ra measurement range 0.01 to 100 μm). Measured by.

Using an EDXRF analyzer (EDX-700L, detection limit: about 0.01% by weight in In) manufactured by Shimadzu Corporation, the joint surface of the used target material after cleaning by polishing is analyzed under the following conditions (semi-quantitative analysis). )did.

<Analysis conditions>
X-ray irradiation diameter: 10 mmφ
Excitation voltage: 10 kV (Na to Sc), 50 kV (Ti to U)
Current: 100 μA
Measurement time: 200 seconds (measured for 100 seconds at each excitation voltage)
Atmosphere: He
Tube: Rh target Filter: None Measurement method: Fundamental parameter method Detector: Si (Li) semiconductor detector

When the joint surface of the used target material before cleaning was analyzed by EDXRF in the same manner as above, Sn, Zn, and In derived from the solder material were 10% by weight or less, 10% by weight or less, and 1% by weight or more, respectively. It was present at 70% by weight, and Cu derived from the support member was present at 1% by weight to 50% by weight. Compared with the analysis result before cleaning, the analysis result of the joint surface after cleaning by the polishing treatment and the presence or absence of visual clogging of the surface of the abrasive after the polishing treatment are used as the treatment result, and A (remarkably removes impurities and Abrasive material is not conspicuously clogged), B (abrasive is sufficiently removed and abrasive material is not conspicuously clogged), E (the amount of each impurity derived from the detected solder material or supporting member is 0.5 wt%). (Or more than the above, or clogging of the abrasive material is confirmed) was classified and evaluated. The evaluation results are shown in Table 1 below (unit: mass% (wt%)). In addition, regarding the elements of the components of the bonding material and the support member that were not detected, the presence or absence of detection of the X-ray peak was also confirmed.

(Example 2)
The polishing work was carried out in the same manner as in Example 1 except that a slash ring having a count # 220 (manufactured by Sankyo Rikagaku Co., Ltd., hardness M, main abrasive grains was alumina) was used as the polishing material. Regarding the abrasive material used, the corners were not chamfered, the polished surface was a rhombus with a side of 12 mm, the surface roughness Ra of the polished surface was 10 μm, the average height of the block bodies was 9 mm, and the distance between the blocks. The average separation distance was 0.7 mm. Further, the grindstone was attached to the belt sander so that the inclination of the grindstone was 75 ° with respect to the polishing direction (rotation direction of the belt sander). The evaluation results are shown in Table 1.

(Comparative Example 1)
The polishing operation was performed in the same manner as in Example 1 except that a polishing pad belt having a count # 240 (manufactured by Officemine Co., Ltd., polishing pad belt WA, main abrasive grains was alumina) was used as the polishing material. The abrasive material used had a surface roughness Ra of 17 μm rather than a block shape. The evaluation results are shown in Table 1.

(Comparative Example 2)
The polishing work was carried out in the same manner as in Example 1 except that an HL belt having a count # 320 (manufactured by Office Mine Co., Ltd., the main abrasive grains were alumina) was used as the polishing material. The abrasive used was not a block-shaped abrasive, but an abrasive in which abrasive grains were bonded to a non-woven fabric. The evaluation results are shown in Table 1.

As can be seen from Table 1, in Examples 1 and 2 using the abrasive having a block-shaped grindstone, clogging of the abrasive was not confirmed, and impurities derived from the solder material and the support member were sufficiently contained. It had been removed. On the other hand, in Comparative Examples 1 and 2 using an abrasive material having no block-shaped grindstone, clogging of the abrasive material was confirmed, and impurities derived from the solder material and the support member were sufficiently contained. Could not be removed. In Example 1, the Al content is lower than that in Comparative Example 1, but it is in a range where there is substantially no problem. Further, in Example 1, even in the initial stage of using the abrasive material, the ground contact property between the abrasive material and the bonding material adhering to the surface of the target material is good, and stable polishing is possible without causing vibration during polishing. Yes, impurities such as solder material could be completely removed.

Furthermore, although not shown in Table 1, when the abrasive material of Example 1 was used, impurities such as the solder material could be removed even after repeated polishing operations. On the other hand, in the case of using the abrasive of Example 2, no clogging was confirmed in the center of the polished surface of the abrasive when the polishing operation was repeated, but the solder material adhered to the sharp corners. It was observed that it was going on. From this, it was found that when the corners of the abrasive are chamfered, even if the In is relatively soft and sticky, the adhesion to the abrasive is suppressed, which is beneficial in repeated use. The use of the suitable abrasive of the present invention is very effective when cleaning the target material for a large flat panel display having a large processing area by polishing or when processing a large amount of the target material.

(Example 3)
By the same method as in Example 1, the sputtering target was separated into a support member (backing plate) and a target material to obtain an aluminum target material having a size of about 200 mm × 100 mm × 15 mm.
The joint surface of the target material is cleaned by polishing in the same manner as in Example 1 except that the abrasive materials of the following conditions 1 to 4 are used as the abrasive material, and the joint surface of the used target material after cleaning is cleaned. EDXRF analysis was performed. The evaluation results are shown in Table 2.

(Condition 1)
A block body (JIS R 6001-1) having a parallel quadrilateral shape (in a plan view) in which the surface roughness Ra of the polished surface is larger than 100 μm, the average height is 3 mm, the average length of the long side is 16 mm, and the average length of the short side is 14 mm. : A resinoid grindstone in which silicon carbide having a particle size corresponding to F36 in 2017 is bonded with a phenol resin) with an average separation distance of 0.5 mm in the direction perpendicular to the polishing direction (direction perpendicular to the rotation direction of the belt sander). An abrasive material adhered to a cloth for polishing cloth (cotton-polyester blended cloth, resin cured product, carbon black mixture) with a mixed rubber so as to have an inclination of 15 ° was prepared. The corners of the block body had a 1.25 mmC chamfered shape, and the size of the abrasive material was 60 mm × 260 mm. A belt-shaped abrasive with both ends fixed was used as the abrasive.

(Condition 2)
A block body (JIS R 6001-1: 2017) having a parallel quadrilateral shape (in a plan view) with a surface roughness Ra of the polished surface of 31 μm, an average height of 3 mm, an average length of the long side of 16 mm, and an average length of the short side of 14 mm. (Resinoid grindstone in which silicon carbide having a particle size corresponding to F60 in the above is bonded with a phenol resin) has an average separation distance of 0.5 mm in the direction perpendicular to the polishing direction (direction perpendicular to the rotation direction of the belt sander). An abrasive material adhered to a cloth for polishing cloth (cotton-polyester blended cloth, resin cured product, carbon black mixture) with a mixed rubber so as to have an inclination of 15 ° was prepared. The corners of the block body had a 1.25 mmC chamfered shape, and the size of the abrasive material was 60 mm × 260 mm. A belt-shaped abrasive with both ends fixed was used as the abrasive.

(Condition 3)
The same abrasive as in Example 1 was used.

(Condition 4)
A block body (JIS R 6001-2) having a parallel quadrilateral shape (in a plan view) with a surface roughness Ra of the polished surface of 7.7 μm, an average height of 3 mm, an average length of the long side of 16 mm, and an average length of the short side of 14 mm. : A resinoid grindstone in which silicon carbide having a particle size corresponding to F400 in 2017 is bonded with a phenol resin) with an average separation distance of 0.5 mm in the direction perpendicular to the polishing direction (direction perpendicular to the rotation direction of the belt sander). An abrasive material adhered to a cloth for polishing cloth (cotton-polyester blended cloth, resin cured product, carbon black mixture) with a mixed rubber so as to have an inclination of 15 ° was prepared. The corners of the block body had a 1.25 mmC chamfered shape, and the size of the abrasive material was 60 mm × 260 mm. A belt-shaped abrasive with both ends fixed was used as the abrasive.

Under any condition, no clogging was confirmed in the abrasive material after polishing. As can be seen from Table 2, impurities derived from the solder material and the support member are sufficiently removed under all conditions, and when the surface roughness Ra of the abrasive material is 100 μm or less, the impurities derived from the solder material and the support member are sufficiently removed. Was reduced to a level of less than 0.1 wt%, and no impurities derived from the solder material or the supporting member were confirmed, especially when the surface roughness Ra of the abrasive material was 20 μm. When the target material is aluminum, when the surface roughness of the abrasive material exceeds 31 μm, especially 100 μm, grooves or dents are generated due to the abrasive material biting into the surface of the target material, and the grooves or dents are formed. It is considered that some impurities derived from the solder material and the support member remained due to the pushing of the solder material and the like. Further, when the surface roughness Ra of the abrasive material was 7.7 μm, it is considered that some impurities derived from the solder material remained on the target material because the polishing power was small.

(Example 4)
By heating (280 ° C.) the bonding layer of the used sputtering target, the sputtering target was separated into a target material and a support member (backing plate).
In addition, the sputtering target is a flat plate type target material made of oxygen-free copper (purity: 99.99%, Vickers hardness: 90, dimensions: 2000 mm × 200 mm × 15 mm) and a support member made of oxygen-free copper in a state before use. (Purity: 99.99%, Dimensions: 2300 mm x 250 mm x 15 mm) is joined with In solder material (thickness of solder layer: 350 μm) (Sn-Zn-In solder material is used for metallization of the target material. ).
Further, the solder material adhering to the joint surface of the separated target material was scraped off with a silicone spatula to remove the solder material as much as possible. After separation from the support member, the target material was cut to a size of about 100 mm × 45 mm × 15 mm.
The joint surface of the target material was polished by the same method as in Example 3 except that the target material was made of oxygen-free copper and the processing speed was 15 cm ² / min, and the used target material was joined after cleaning. The surfaces were EDXRF analyzed. The evaluation results are shown in Table 3.

Under any condition, no clogging was confirmed in the abrasive material after polishing. As can be seen from Table 3, impurities derived from the solder material and the support member are reduced under all conditions, and when the surface roughness Ra of the abrasive material is 10 μm or more, the impurities derived from the solder material and the support member are 0. It was reduced to a level of less than .5 wt%, and no impurities derived from the solder material or the support member were confirmed, especially when the surface roughness Ra of the abrasive material was 20 μm or 31 μm. When the target material is pure copper, when the surface roughness of the abrasive material exceeds 100 μm, grooves or dents are generated due to the abrasive material biting into the surface of the target material, and solder material or the like is formed in the grooves or dents. It is considered that some impurities derived from the solder material and the support member remained after being pushed. Further, when the surface roughness Ra of the abrasive material was 7.7 μm, it is considered that impurities derived from the solder material remained on the target material because the polishing power was small.

(Example 5)
By the same method as in Example 1, the sputtering target was separated into a support member (backing plate) and a target material to obtain an aluminum target material having a size of about 200 mm × 100 mm × 15 mm.
The same method as in Example 1 (Example 5-1) except that the processing speed was set to 480 cm ² / min, the contact wheel (roller) was fitted with a rubber contact manufactured by Officemine Co., Ltd. (hardness 55 °, φ55 mm × The joint surface of the target material was polished by the same method as in Example 1 (Example 5-2) except that the processing speed was set to 480 cm ² / min using a width of 60 mm)), and the used target after cleaning was used. The joint surface of the material was analyzed by EDXRF. The evaluation results are shown in Table 4. The "center" of the "evaluation position" means the position of the center of the target material, and the "edge" of the "evaluation position" means the position of the edge of the target material.

Under any condition, no clogging was confirmed in the abrasive material after polishing. As can be seen from Table 4, impurities derived from the solder material and the support member are sufficiently removed under all conditions, and especially when a rubber roller is used (Example 5-2), solder is used even if the processing speed is high. Impurities derived from the material and support members were completely removed. Unlike the sponge roller, which is a soft material, the rubber roller is a hard material, so that it can be polished by applying a higher load, and the abrasive is polished so as to bite into the joint surface of the target material. Therefore, it is considered that the solder material is further removed.

(Example 6)
The joint surface of the target material was polished by the same method as in Example 1 except that the treatment speed was 200 cm ² / min, and the joint surface of the used target material after cleaning was analyzed by EDXRF. The evaluation results are shown in Table 5.

(Example 7)
A target material was prepared by polishing the joint surface of the target material by the same method as in Example 1. After that, a polishing pad belt with a count of # 180 (manufactured by Officemine Co., Ltd., polishing pad belt WA, main abrasive grains are alumina) is attached to the belt sander attached in Example 1 to process the polished target material. Further polishing was performed at a speed of 400 cm ² / min. The joint surface of the used target material after cleaning was analyzed by EDXRF. The evaluation results are shown in Table 5.

A part of the used target material after cleaning obtained in Examples 6 and 7 was collected, melted at 850 ° C. under vacuum (about 0.03 Torr), and cooled in the air to obtain a recycled ingot. Manufactured.

The amount of impurities contained in the recycled ingot was subjected to a trace analysis of In, Sn, Zn, and Cu using GDMS (VG9000, manufactured by VG Elemental), respectively. The analysis results are shown in Table 6 below, along with the analysis results of the unused target material, which is a reference example, and the ingots produced from the used target material (before cleaning) by the same method (unit: mass ppm (wt ppm). )).

As shown in Table 6, the total amount of impurities derived from the solder material (In, Sn, Zn) and the support member (Cu) contained in the recycled ingots produced in Examples 6 and 7 is less than 4 ppm on a mass basis. It turned out to be. The total amount of impurities was also less than 10 ppm. Further, as can be seen from Tables 5 and 6, by using particles having a composition close to that of the target material as the abrasive grains of the abrasive material, the risk of contamination by the abrasive material can be further reduced.

Although the flat plate type target material has been described in the above Examples and Comparative Examples, the same result can be obtained by performing the same treatment on the cylindrical target material to be joined to the backing tube by using the joining material. it can.

According to the method for polishing the target material of the present invention, clogging of the grindstone and the abrasive material can be reduced, and impurities derived from the bonding material and the supporting member forming the bonding layer from the target material can be reduced and removed. it can. Therefore, it is useful for cleaning and recycling used target materials.

1 Sputtering target 2 Target material 2a Sputtering surface 2b Joint surface 3 Support member 3a Joint surface 10 Polishing tool 11 Main body 12 Polishing part 13 Abrasive 15 1st roller 16 2nd roller 20 Sheet body 21 Block body 22 Gap

Claims (11)

1. A method of polishing a target material separated from a sputtering target formed by joining a target material and a support member with a joining material.
   The joint surface of the target material that has been joined to the support member includes a plurality of block bodies made of a grindstone, and the plurality of block bodies are on the same surface so as to be separated from adjacent block bodies via a gap. A method of polishing a target material, which comprises polishing with an arranged abrasive.
2. The method for polishing a target material according to claim 1, wherein the abrasive is formed in a belt shape, and the joint surface of the target material is polished while rotating the abrasive.
3. The target material according to claim 2, wherein the belt-shaped abrasive is hung around a roller, and the joint surface of the target material is polished while pressing the abrasive against the target material using the roller. Polishing method.
4. The method for polishing a target material according to claim 3, wherein the roller is a rubber roller.
5. The method for polishing a target material according to any one of claims 1 to 4, wherein the Vickers hardness of the target material is 150 or less.
6. The method for polishing a target material according to any one of claims 1 to 5, wherein the main component of the target material is aluminum or copper.
7. The Vickers hardness of the target material is 10 or more and 40 or less.
   The method for polishing a target material according to claim 5, wherein the surface roughness Ra of the block body of the abrasive material is 10 μm or more and 30 μm or less.
8. The Vickers hardness of the target material is 40 or more and 120 or less.
   The method for polishing a target material according to claim 5, wherein the surface roughness Ra of the block body of the abrasive material is 12 μm or more and 50 μm or less.
9. The method for polishing a target material according to any one of claims 1 to 8, wherein the bonding material is a solder material containing an alloy of tin, zinc, indium, lead or a metal thereof.
10. A method for producing a target material, which comprises treating the target material by the polishing method according to any one of claims 1 to 9.
11. A method for producing a recycled ingot, which comprises casting the target material obtained by the production method according to claim 10 as a raw material to produce a recycled ingot.

Images