TWI866961B - Regenerated casting block, method for producing target material, and method for producing recycled casting block - Google Patents

Abstract

The present invention provides a method for grinding a target material that can remove bonding material from a target material and reduce clogging of a grinding material. The method for grinding a target material is a method for grinding a target material separated from a sputtering target, wherein the sputtering target is formed by bonding a target material to a supporting member using a bonding material, and the method includes: grinding a bonding surface of the target material bonded to the supporting member using a grinding material, wherein the grinding material includes a plurality of blocks including a grinding stone, and the plurality of blocks are arranged on the same surface in a manner separated from adjacent blocks by gaps.

Description

Regenerated casting block, target material manufacturing method and recycled casting block manufacturing method

The present invention relates to a method for grinding a target material, a method for manufacturing a target material processed by the grinding method, and a method for manufacturing a casting (hereinafter also referred to as a regenerated casting) using the target material obtained by the manufacturing method as a raw material.

Sputtering targets are usually made by bonding (bonding) target materials including ceramics, metals, or alloys such as oxides to supporting members such as backing plates or backing tubes including metals and alloys using bonding materials such as solder. By applying such sputtering targets to sputtering, a thin film of metal or oxide can be formed on a substrate. Regardless of the type of target, it is not completely consumed by sputtering, but is recycled after use. For example, metals such as aluminum and copper can be reused as castings (slabs, ingots) by melting and casting.

In order to reuse the recovered target material, it is necessary to remove the surface attachments such as bonding materials attached to the target material. For example, there is a known removal method based on chemical treatment such as acid treatment or grinding. Previously, as a method for grinding and grinding used target materials, there is a method described in Japanese Patent Publication No. 2002-120155 (Patent Document 1). In this target grinding method, the supporting member is removed from the used sputter-plated target, and the bonding materials attached to the target material are removed using an alumina-based grinding stone or a diamond-based grinding stone with an abrasive grain rate of 30% to 48%, a bonding agent rate of 7% to 15%, and a porosity of 45% to 63%.

[Prior art literature] [Patent Literature]

[Patent document 1] Japanese Patent Publication No. 2002-120155

However, in the conventional target grinding method, the grinding stone or grinding material is clogged and the clog cannot be sufficiently reduced. In addition, the bonding material of the target cannot be fully removed. The grinding stone or grinding material needs to be replaced frequently, which is laborious and time-consuming. This is particularly prominent in targets for large-sized flat panel displays.

Therefore, the subject of the present invention is to provide a method for grinding a target material, a method for manufacturing a target material processed by the grinding method, and a method for manufacturing a regenerated casting using the target material obtained by the manufacturing method as a raw material. The method for grinding a target material can reduce the clogging of the grinding material caused by the bonding material, and can reduce and remove impurities from the bonding material and the supporting member from the target material.

In order to solve the above-mentioned problem, the target material grinding method of the present invention is a method for grinding a target material separated from a sputtering target, wherein the sputtering target is formed by bonding the target material to a supporting member using a bonding material, and the method includes: grinding the bonding surface of the target material bonded to the supporting member using a grinding material, wherein the grinding material includes a plurality of blocks including a grinding stone, and the plurality of blocks are arranged on the same surface in a manner of being separated from adjacent blocks by gaps.

According to the target grinding method of the present invention, by grinding the bonding surface of the target using a grinding material containing a plurality of blocks, the bonding material can be removed from the target. In addition, the removed bonding material can be discharged to the outside from the gap between adjacent blocks, thereby reducing the clogging of the grinding material.

In addition, in one embodiment of the target material grinding method, the grinding material is formed into a belt shape, and the bonding surface of the target material is ground while the grinding material is rotated.

According to the above-mentioned implementation form, since the bonding surface of the target material is polished while the belt-shaped polishing material is rotated, the removed bonding material can be more reliably discharged to the outside.

In addition, in one embodiment of the target material grinding method, the belt-shaped grinding material is hung on a roller, and the bonding surface of the target material is ground while the grinding material is pushed to the target material using the roller.

According to the above-mentioned implementation form, since the bonding surface of the target is ground while the grinding material is pushed to the target using a roller, the bonding material can be removed from the bonding surface of the target more reliably.

In addition, in one embodiment of the target grinding method, the roller is a rubber roller.

According to the embodiment, since the roller is a rubber roller, the hardness of the rubber roller can be used to grind the target material so that the grinding material bites into the target material's joint surface, and the joint material can be removed more reliably from the target material's joint surface.

In addition, in one embodiment of the target material grinding method, the Vickers hardness of the target material is less than 150.

According to the above-mentioned implementation form, the bonding material can be removed from the bonding surface of the target material having a Vickers hardness of 150 or less.

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

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

In addition, in one embodiment of the target material grinding method, the Vickers hardness of the target material is greater than 10 and less than 40, and the surface roughness Ra of the block of the grinding material is greater than 10 μm and less than 30 μm.

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

In addition, in one embodiment of the target material grinding method, the Vickers hardness of the target material is greater than 40 and less than 120, and the surface roughness Ra of the block of the grinding material is greater than 12μm and less than 50μm.

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

In addition, in one embodiment of the target grinding method, the bonding material is a solder material containing tin, zinc, indium, lead or an alloy of these metals.

In addition, in one embodiment of the target material manufacturing method, a target material (or used target material) manufacturing method is provided, which includes processing the target material using the grinding method.

According to the above-mentioned implementation form, a used target material with less impurities (bonding material) can be manufactured.

In addition, in one embodiment of the method for manufacturing a regenerated casting, the target material obtained by the manufacturing method is used as a raw material for casting to manufacture a regenerated casting.

According to the above-mentioned implementation form, a regenerated casting with less impurities (bonding material) can be produced.

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

1: Sputtering target

2: Target material

2a: Splash coating

2b: Joint surface

3: Support components

3a: Joint surface

10: Grinding tools

11: Main body

12: Grinding Department

13: Abrasive materials

15: First Roller

16: Second Roller

20: Plate-like body

21: Blocky

23: Gap

A: Arrow

R: Arrow

θ: angle

FIG1 is an explanatory diagram showing an embodiment of a used sputtering target of the present invention.

FIG2 is an explanatory diagram showing an embodiment of a method for separating a used sputtering target into a target and a supporting member when the target of the present invention is a flat plate.

FIG3 is an explanatory diagram showing an embodiment of the target material polishing method of the present invention.

FIG4A is a plan view showing an embodiment of the abrasive material of the present invention.

Figure 4B is a cross-sectional view taken along line X-X of Figure 4A.

The present invention is described in detail below using illustrated implementation forms.

(Implementation form)

Figures 1 to 3 are explanatory diagrams showing an embodiment of the target material grinding method of the present invention. As shown in Figures 1 to 3, the method is a method of grinding a target material 2 separated from a used sputtering target 1.

In the present invention, "sputtering target" is formed by bonding a target material and a supporting member using a bonding material. As long as it can be used in sputtering, the shape and material of the target material or the supporting member are not particularly limited. When the sputtering target is a flat plate, a flat support plate can be used as a supporting member. In addition, when the sputtering target is a cylindrical type, a cylindrical support tube can be used as a supporting member. Here, a cylindrical support tube can be inserted into the inside of the cylindrical target material, and the inner circumference of the cylindrical target material can be bonded to the outer circumference of the support tube using a bonding material.

As shown in FIG1 , the sputtering target 1 is formed by bonding the target material 2 and the supporting member 3 using a bonding material.

The target material 2 has a sputtering surface 2a on the upper surface and a bonding surface 2b on the lower surface. During the sputtering of the target material 2, the inert gas ionized by sputtering collides with the sputtering surface 2a. The target atoms contained in the target material 2 are ejected from the sputtering surface 2a collided with by the ionized inert gas. The ejected atoms are accumulated on a substrate arranged opposite to the sputtering surface 2a and form a thin film on the substrate.

The target material 2 may be mainly composed of metal. For example, the target material 2 may be made of a material selected from the group consisting of the following components: aluminum, copper, chromium, iron, tantalum, titanium, zirconium, tungsten, molybdenum, niobia, silver, cobalt, ruthenium, platinum, palladium, gold, rhodium, indium and nickel, and alloys containing metals selected from these metal groups. The materials constituting the target material 2 are 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 further preferably 12 or more and 90 or less. If the grinding method of this embodiment is applied to the target material 2 in this range of Vickers hardness, the bonding material and the like can be removed more appropriately. The Vickers hardness can be confirmed by the Vickers hardness test (Japanese Industrial Standards (JIS) Z 2244: 2003).

The main component of the target 2 is preferably aluminum (purity 99.99% (4N) or more, preferably purity 99.999% (5N) or more) or copper (purity 99.99% (4N) or more). When the main component of the target 2 is aluminum, the Vickers hardness of the target 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 2 is copper, the Vickers hardness of the target 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 is no particular limitation on the size, shape and structure of the target 2. The target 2 can be a flat plate or a cylindrical type.

When the target 2 is a flat plate, the size of the target 2 in the longitudinal direction is, 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 size in the width direction (the direction perpendicular to the longitudinal direction) is, 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 2 can be formed into a strip, or the short side and the long side can be 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 2 is cylindrical, the size of the target 2 in the longitudinal direction is, 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, further preferably 2500 mm or more and 3000 mm or less. The outer diameter of the target 2 is 75 mm or more and 400 mm or less, preferably 100 mm or more and 350 mm or less, further preferably 120 mm or more and 300 mm or less, further preferably 140 mm or more and 250 mm or less, further preferably 150 mm or more and 200 mm or less. The inner diameter of the target 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, further preferably 100 mm or more and 160 mm or less, further preferably 110 mm or more and 150 mm or less. In the present invention, even a target 2 for a large flat panel display can be easily processed.

When the supporting member 3 is a supporting plate, the size, shape and structure of the supporting plate are not particularly limited as long as the supporting plate is a plate-shaped plate on which the target material 2 can be placed. The length of the supporting 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, and more preferably 1500 mm or more and 3500 mm or less. The length of the supporting plate in the short side direction is, for example, 100 mm or more and 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 supporting plate can be formed into a strip, or the short side and the long side can be the same length. The support plate includes a conductive material, including: a metal selected from the group consisting of copper, chromium, aluminum, titanium, tungsten, molybdenum, niobium, iron, cobalt and nickel, or an alloy containing at least one metal selected from the group, preferably copper (oxygen-free copper), chromium-copper alloy or aluminum alloy. On the other hand, when the supporting member is a support tube, the size of the support tube is usually longer than the cylindrical target because it is inserted into the inside of the cylindrical target for bonding, and the outer diameter of the support tube is preferably slightly smaller than the inner diameter of the cylindrical target. The metal or alloy used for the structure is the same as that of the support plate, among which stainless steel (SUS), titanium, titanium alloy, etc. are preferred.

The supporting member 3 has a bonding surface 3a on the upper surface. The bonding surface 3a of the supporting member 3 is bonded to the bonding surface 2b of the target material 2 via a bonding material. The bonding material includes, for example, a solder material or a brazing material.

The solder material is a material containing a metal or alloy with a low melting point (e.g., below 723 K). Examples of the solder material include: a metal selected from the group consisting of indium (In), tin (Sn), zinc (Zn), lead (Pb), silver (Ag), copper (Cu), bismuth (Bi), cadmium (Cd) and antimony (Sb), or an alloy containing at least one metal selected from the group. Among these, the solder material is preferably the following solder, which contains tin, zinc, indium, lead, or an alloy containing at least one metal selected from the group consisting of Sn, Zn, In and Pb. More specifically, the solder material includes: 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, etc.

The brazing material can be used without any particular limitation as long as it is a metal or alloy that can bond the target material 2 and the supporting member 3 and has a lower melting point than the target material 2 and the supporting member 3.

The bonding material usually uses solder materials such as In or In alloy, Sn or Sn alloy with a low melting point. These solder materials are soft and can easily enter the unevenness of the surface of the grinding material or grinding stone, or easily adhere to the surface, so it is easy to cause clogging of the grinding material or grinding stone. When using the above-mentioned solder material as the bonding material, if the grinding method of this embodiment is applied, a more significant effect can be obtained, and the bonding material can be removed more appropriately.

For example, the solder material forms 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 the target material 2 can be joined to the solder material. Alternatively, the joining material also forms a diffusion layer (alloy layer) with the metal contained in the support member 3 at the joint surface with the support member 3, thereby the support member 3 can be combined with the solder material. Therefore, by using this solder material to form a solder layer between the target material 2 and the support member 3 as a joint layer, the target material 2 and the support member 3 can be joined.

There is a situation where a metallizing layer is formed on the bonding surface 2b of the target 2 or the bonding surface 3a of the support member 3. Usually, if the solder material is simply placed on the target 2 or the support member 3 and melted, the oxide film on the surface of the target 2 or the support member 3 may affect it and sufficient bonding strength cannot be obtained. Therefore, first, a metallizing layer may be provided to improve the wettability of the solder material relative to these surfaces. In this case, the bonding layer formed between the target 2 and the support member 3 includes: a solder layer, a metallizing layer formed on the bonding surface 2b of the target 2, and a metallizing layer formed on the bonding surface 3a of the support member 3.

The so-called "metallization" is generally a treatment method that can be used to metallize a non-metal surface. Regarding the metallization layer, when the target 2 or the supporting member 3 has an oxide film, for example, a metallization solder material can be used to form it on the target 2 or the supporting member 3. The metallization layer can be formed, for example, by using an ultrasonic soldering iron and utilizing the vibration energy (cavitation effect) of the ultrasonic wave to destroy the oxide film of the target 2 or the supporting member 3, and at the same time, by heating, the metal atoms contained in the metallization solder material and the metal atoms contained in the target 2 or the supporting member 3 are chemically bonded together with the oxygen atoms in the oxide film.

The solder that can be used in metallization is, for example, the following materials, which contain a metal selected from the group consisting of In, Sn, Zn, Pb, Ag, Cu, Bi, Cd and Sb, or an alloy containing at least one metal selected from the group, 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, etc. It is sufficient to appropriately select a material with high affinity to the target material 2 or the supporting member 3.

The metallization layer can also be combined with the solder layer, and can be located between the target material 2 and the solder layer, or between the supporting member 3 and the solder layer, respectively, so as to play a role in firmly combining the target material 2 and the bonding layer, and the supporting member 3 and the bonding layer.

In this specification, the so-called bonding layer includes not only the case where the layer is composed of bonding materials such as solder and brazing materials, but also the case where the layer includes at least one of the metallization layer formed on the bonding surface 2b of the target material 2 and the metallization layer formed on the bonding surface 3a of the supporting member 3.

Regarding the thickness of the solder layer, when the supporting member 3 is a flat plate, for example, it can be within the range of 50 μm or more and 500 μm or less, and when the supporting member 3 is a cylindrical type, for example, it can be within the range of 250 μm or more and 1500 μm or less. Regarding the thickness of the metallization layer, when the supporting member 3 is both a flat plate type and a cylindrical type, for example, it can be within the range of 1 μm or more and 100 μm or less.

As shown in FIG1 , the sputtering surface 2a of the target material 2 is sputtered, and the sputtering target 1 is used. Thereafter, as shown in FIG2 , the target material 2 is separated (or peeled off) from the used sputtering target 1. There is no particular limitation on the method of separating the target material 2 from the supporting member 3. For example, heat (e.g., above 180°C and below 300°C) may be applied to the bonding layer to soften or melt the bonding layer, and the bonding layer may be physically destroyed as needed, thereby separating the target material 2 from the sputtering target 1.

In the case where the target 2 is a flat plate, the separated target 2 includes the metallized layer on the surface bonded to the support plate (bonding surface 2b, sometimes referred to as "bonding surface"), and at least a portion of the bonding layer is attached and remains. Depending on the situation, there is also a situation where not only the bonding layer remains, but also impurities from the support plate diffuse and remain in the bonding layer or the surface of the bonding surface side of the target 2.

It is preferred to scrape off the bonding layer attached to the bonding surface 2b after separation as much as possible using a scraper (e.g., a silicone scraper) before grinding the target 2. Furthermore, it is difficult to completely remove the bonding material attached to the bonding surface 2b after separation by scraping off the bonding material using a scraper, and in particular, it is impossible to remove the metallization layer firmly bonded to the target 2. In addition, there is a case where the bonding material also adheres to the sputtered surface 2a or the side surface of the target 2 and remains. The reasons for this are, for example, as follows Reasons such as: when the target material 2 is separated, the molten bonding material adheres to the sputtered surface 2a or the side surface; or in order to store the used target materials 2 after separation by stacking each other, the bonding surface 2b contacts the sputtered surface 2a or the side surface, so that the bonding material of the bonding surface 2b adheres to the sputtered surface 2a or the side surface. Therefore, the polishing method of the present invention can also be applied to the sputtered surface or the side surface.

In the case of a cylindrical target, the cylindrical target can be bonded to the outer periphery of a cylindrical support tube using a bonding material. Therefore, similarly to the case of the flat target, the bonding material adheres to the bonding surface (inner periphery) of the target after separation, and the removal of the bonding material is more difficult than that of the flat target. In addition, similarly to the case of the flat target, there is a case where the bonding material also adheres to the sputtered surface of the cylindrical target and remains. Furthermore, there is a case where components originating from the support tube may also be mixed in as impurities. Therefore, in the cylindrical target, the polishing method can also be applied to the bonding surface of the target after separation, i.e., the inner periphery, or the sputtered surface, i.e., the outer periphery. Furthermore, when processing the bonding surface, i.e., the inner circumference of the target material, for example, it is preferable to cut the target material in a cylindrical manner by dividing the circumference into two equal parts (i.e., dividing the cylindrical target material into two equal parts parallel to the longitudinal direction of the cylinder), and process the target material in a manner that exposes the bonding surface, i.e., the inner circumference, and then apply the grinding method.

The presence of the bonding material in the separated target can be confirmed, for example, by energy dispersive X-ray fluorescence analysis (EDXRF). Furthermore, when the metal element diffuses from the supporting member to the target, the metal element can also be confirmed by EDXRF. In addition, wavelength dispersive X-ray fluorescence analysis (WDXRF), electron probe microanalysis (EPMA), Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (TOF-SIMS), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray diffraction (XRD) Analysis) and other analysis methods can also confirm impurities from bonding materials and supporting components. In terms of the simplicity of analysis and the breadth of the analysis range, EDXRF and WDXRF are preferred for confirmation.

In the subsequent regeneration process, if a casting (hereinafter also referred to as a "slab" or "ingot") is produced by directly melting and casting the separated target material with the bonding material attached, and the target material is produced again from the casting, impurities derived from the components of the attached bonding material will be mixed into the target material. Furthermore, if metal elements diffuse from the supporting member to the target material and are mixed as impurities, there is a case where the metal elements are mixed into the casting as impurities.

At least the joint surface 2b formed by the target material 2 and the supporting member 3 in the target material is polished, thereby cleaning the target material.

FIG4A is a plan view of the abrasive material 13, and FIG4B is a cross-sectional view taken along the line X-X of FIG4A. As shown in FIG4A and FIG4B, the abrasive material 13 includes a sheet 20 and a plurality of blocks 21 disposed on one side of the sheet 20. The sheet 20, for example, contains rubber and is formed into a strip shape. The plurality of blocks 21 are arranged on the same side, i.e., one side of the sheet 20.

In FIG. 4A , the block 21 is formed into a parallelogram shape when viewed from above, but the shape is not particularly limited, and may be a rectangle, square, rhombus, perfect circle, ellipse, etc., or may be a combination of these shapes. In addition, the block 21 may be a hemisphere, cone, pyramid, etc., as long as it is a convex shape relative to the processed surface. In terms of maintaining the grinding force relative to the solder material, it is preferably a shape in which the surface facing the processed surface is a plane. In addition, in terms of the viewpoint that the block 21 can be closely arranged, it is more preferably a parallelogram, rectangle, square, or rhombus when viewed from the side of the facing processed surface. Regarding the size of the grinding surface of the block 21, one side or diameter is 5 mm or more and 30 mm or less, 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. If the size of the grinding surface of the block 21 is within the above range, the grinding force relative to the solder material can be maintained, and the clogging of the grinding surface of the grinding material can be prevented.

The multiple blocks 21 are preferably arranged in a staggered manner along the grinding direction shown by the arrow R in FIG. 4A. Thereby, the blocks 21 touch the processed surface without gaps, and the solder material can be removed efficiently. Furthermore, the multiple blocks 21 are preferably arranged in a straight line along the arrow A direction intersecting at a predetermined angle θ relative to the arrow R direction. The predetermined angle θ is greater than 10° and less than 90°, preferably greater than 30° and less than 85°, more preferably greater than 45° and less than 80°, and further preferably greater than 60° and less than 75°. The multiple blocks 21 can be arranged in a straight line with an inclination relative to the direction orthogonal to the arrow R direction. By arranging in a manner to form the predetermined angle θ, the block 21 can be prevented from being damaged or blocked by the solder material.

The adjacent block 21 is separated by a gap 23. The block 21 includes a grinding stone. The grinding stone includes, for example, a mixture in which abrasive grains such as silicon carbide, chromium oxide, zirconium oxide, vanadium oxide, zirconium stone, diamond, boron nitride, and aluminum oxide are bound together by a binder including a resin. Examples of the binder include epoxy resin, polyester resin, phenol resin, melamine resin, acrylic resin, urea resin, polyvinyl alcohol resin, and polyvinyl acetal resin. The abrasive grain composition or abrasive grain size and the type of binder can be selected according to the composition of the target material or the solder material, and a plurality of types can be selected. In order to reduce the contamination of the target material by abrasive particles, it is better to select an abrasive material with a composition close to that of target 2.

From the perspective of efficiently removing impurities from the bonding material or the supporting member, the height of the block 21 is preferably the same, and the average height of the block 21 is, for example, 0.5 mm or more, preferably 1 mm or more, more preferably 1.5 mm or more, and more preferably 2 mm or more, and less than 10 mm, preferably less than 8 mm, more preferably less than 6 mm, and more preferably less than 5 mm, and particularly preferably less than 4 mm. If the average height of the block 21 is above the lower limit, the life of the abrasive material is extended and the replacement frequency of the abrasive material can be reduced. If it is below the upper limit, even in the initial use of the abrasive material, the contact with the bonding material attached to the target material 2 is good. In addition, the grinding can be performed stably without generating vibration during grinding, and impurities from the bonding material or the supporting member can be efficiently removed.

When the average height of the blocks 21 is below the upper limit, from the viewpoint of efficiently releasing the bonding material, the average separation distance of the blocks 21 (the width of the gap 23 in FIG. 4B as the X-X section of FIG. 4A) is, for example, 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.3 mm or more, and further preferably 0.4 mm or more, and is 1 mm or less, preferably 0.8 mm or less, more preferably 0.7 mm or less, and further preferably 0.6 mm or less. Here, the so-called X-X section of FIG. 4A is a section of the blocks 21 adjacent to each other in the direction intersecting the direction of arrow A, in other words, a section intersecting the blocks 21 of the first row arranged in a straight line along the direction of arrow A and the blocks 21 of the second row adjacent to the blocks 21 of the first row.

If the average separation distance of the block 21 (the width of the gap 23) is above the lower limit, even the grinding chips of metals and alloys that are soft and sticky like solder can be discharged efficiently from the gap 23, and clogging of the grinding material can be prevented. If the average separation distance of the block 21 (the width of the gap 23) is below the upper limit, the risk of the block 21 detaching from the sheet 20 can be reduced. In FIG. 4B, the multiple block 21 is completely separated, but if it is within a range that does not affect clogging, the multiple block 21 can also be a structure in which the block 21 is connected near the top of the sheet 20, that is, the bottom of the block 21. Thereby, the next step of the block 21 and the sheet 20 can be easily performed. The periphery of the upper surface of the block 21 is preferably C-chamfered or R-chamfered within a range of 0.1 mm or more, preferably 0.2 mm or more, more preferably 0.5 mm or more, and more preferably 0.7 mm or more, and less than 3 mm, more preferably less than 2 mm, and more preferably less than 1.5 mm. If the periphery of the block 21 is chamfered within the above range, the block 21 can be prevented from being damaged, and the accumulation of solder in the corner caused by the corner of the block 21 penetrating into the solder layer can be prevented.

The surface roughness of the polished surface of the block 21 of the abrasive material 13, such as the arithmetic mean roughness Ra, can be adjusted by the size of the abrasive grains or the amount of the abrasive grains, and can be appropriately selected according to the Vickers hardness of the target material 2. For example, in a target material containing a metal or an alloy having a Vickers hardness of 150 or less, the surface roughness Ra of the polished surface of the block 21 is 3 μm or more, preferably 5 μm or more, more preferably 9 μm or more, further preferably 10 μm or more, particularly preferably 15 μm or more, and is 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 comprising a metal or an alloy or a target material whose main component is aluminum and whose Vickers hardness is greater than or equal to 10 and less than or equal to 40, the surface roughness Ra in the polished surface of the block 21 is greater than or equal to 3 μm and less than or equal to 150 μm, preferably greater than or equal to 3 μm and less than or equal to 100 μm, more preferably greater than or equal to 5 μm and less than or equal to 50 μm, further preferably greater than or equal to 7 μm and less than or equal to 30 μm, further preferably greater than or equal to 10 μm and less than or equal to 27 μm, and particularly preferably greater than or equal to 15 μm and less than or equal to 25 μm. In addition, in a target material containing metal or alloy with a Vickers hardness of 40 to 120 or a target material whose main component is copper, the surface roughness Ra of the polished surface of the block 21 is 5 μm to 150 μm, preferably 8 μm to 120 μm, more preferably 10 μm to 100 μm, further preferably 12 μm to 50 μm, further preferably 12 μm to 45 μm, and particularly preferably 15 μm to 40 μm. If the surface roughness Ra of the grinding surface of the block 21 of the grinding material 13 is above the lower limit, it can have sufficient grinding force relative to the solder material or the target material 2. In addition, if the surface roughness Ra is below the upper limit, the risk of large grooves or depressions on the processing surface of the target material 2 and the risk of grinding chips being stuck in the grooves or depressions or the solder material being pressed into the processing surface of the target material 2 can be reduced, thereby efficiently removing impurities from the solder material or the supporting member. In order to remove impurities from the solder material or the supporting member from the used target material 2, it is preferable to not only reduce the clogging caused by the soft and sticky metal and alloy like the bonding material, but also adjust the surface roughness of the grinding surface of the block 21 of the grinding material 13 according to the Vickers hardness of the target material that becomes the base of the bonding layer.

The operation method of the grinding material is not particularly limited. Specifically, if the block 21 on the surface of the grinding material can be preferably in close contact with the surface to be the object, such as the bonding surface 2b of the target material 2, and the method can be polished at the same time, any method known to those skilled in the art can be used, preferably using a grinding device equipped with the grinding material. For example, commercially available orbital sanders, delta sanders, random sanders, disk grinders, belt sanders, straight grinders, electric polishers, portable electric tools or pneumatic tools, flat grinding discs (for example, manufactured by Kuroda Seiko Co., Ltd. or Okamoto Machine Works Co., Ltd.) or deburring machines (for example, manufactured by ST-Link Co., Ltd.) and other large-scale devices can be used. Furthermore, grinding can also be performed multiple times on the same part, preferably more than 1 time and less than 10 times, and more preferably more than 2 times and less than 5 times.

The movement direction of the grinding material installed in the grinding device is not particularly limited. Specifically, it can be listed as follows: linear reciprocating motion in the horizontal direction relative to the processed surface, rotational motion in the horizontal direction relative to the processed surface (the rotation axis is in the vertical direction relative to the processed surface), rotational motion in the vertical direction relative to the processed surface (the rotation axis is in the horizontal direction relative to the processed surface), etc. In order to further exert the effect of the grinding material of the present invention, it is better to use a grinding device that uses the mounted grinding material to perform rotational motion, and it is more preferable to use a grinding device that performs rotational motion in the vertical direction relative to the processed surface (the rotation axis is in the horizontal direction relative to the processed surface).

FIG. 3 is an embodiment of the target material grinding method of the present invention, and is an example of using a grinding tool 10, that is, a belt sander (a grinding device that performs a rotational motion in a direction perpendicular to the surface to be processed) as a grinding device. The grinding tool 10 has a main body 11 and a grinding part 12 mounted on the main body 11. The main body 11 has a grip for a worker to hold, and a motor that drives the grinding part 12. The grinding part 12 has a first roller 15 on the driving side, a second roller 16 on the driven side, and a belt-shaped grinding material 13 wound around the first roller 15 and the second roller 16. The first roller 15 is connected to the motor. Moreover, by being driven by the motor, the first roller 15 rotates, and the grinding material 13 rotates in the direction of the arrow R. That is, the grinding direction is the direction of arrow R.

As shown in FIG3 , when the bonding surface 2b of the target 2 is ground using the grinding tool 10, at least the first roller 15 of the first roller 15 and the second roller 16 is used to push the grinding material 13 to the target 2 and rotate the grinding material 13 while grinding the bonding surface 2b of the target 2. At this time, the grinding material 13 is mounted on the grinding tool 10 in such a manner that the surface of the block 21 in the grinding material 13 (the surface facing the surface that contacts the sheet body 20) is oriented to contact the bonding surface 2b of the target 2. The operator moves the grinding tool 10 along the bonding surface 2b of the target 2 while grinding the entire bonding surface 2b of the target 2.

According to the grinding method of the target material 2, by grinding the bonding surface 2b of the target material 2 using the grinding material 13 including a plurality of blocks 21, the bonding material can be removed from the target material 2, and the removed bonding material can be discharged to the outside from the gap 23 between the adjacent blocks 21, thereby reducing the clogging of the grinding material 13.

In addition, since the bonding surface 2b of the target material 2 is ground while the belt-shaped grinding material 13 is rotated, the removed bonding material can be more reliably discharged to the outside.

In addition, since the first roller 15 is used to push the grinding material 13 to the target material 2 while grinding the bonding surface 2b of the target material 2, the bonding material can be removed more reliably from the bonding surface 2b of the target material 2.

The first roller 15 can be a roller made of resin or metal such as sponge or rubber, preferably a resin roller, and more preferably a rubber roller. Accordingly, the hardness and flexibility of the rubber roller make the grinding material 13 and the bonding surface 2b of the target material 2 more closely connected, and further load can be applied while grinding, so that the bonding material can be removed more reliably from the bonding surface 2b of the target material 2.

If the bonding material on the target 2 can be fully removed, the risk of clogging of the abrasive material is significantly reduced, so the fine grinding step using a known abrasive material can also be performed. For example, in order to improve the contamination caused by abrasive grains, it can be listed as follows: using an abrasive material with a composition close to that of the target 2 for fine grinding, etc.

According to the target polishing method of this embodiment, impurities originating from the bonding material constituting the bonding layer (including the metallized layer when there is a metallized layer) and the support member 3 can be simply and sufficiently removed from the used target 2. In this specification, "sufficiently removed" means that the amount of elements contained in the impurities originating from the bonding material constituting the bonding layer (including the metallized layer when there is a metallized layer) and the amount of elements contained in the impurities originating from the support member 3 in the bonding surface 2b formed by bonding the target 2 and the support member 3 are removed to the amount of each element detected by EDXRF measurement is 0.5wt% or less, preferably 0.2wt% or less, and more preferably 0.1wt% or less.

<Method for manufacturing target material (or used target material)>

The manufacturing method of a target material (or a used target material) of an embodiment of the present invention includes: treating the target material using the grinding method of the target material of the embodiment. The target material treated as described above can be used in the manufacture of the regenerated casting described later. The manufacturing method of the target material (or a used target material) may include not only the treatment using the grinding method of the target material, but also other treatments. For example, it may also include a treatment for removing grinding shavings attached to the used target material after grinding (for example, using high-pressure air blowing or running water cleaning). By removing the grinding shavings, when the used target material after cleaning is dissolved and cast as a raw material, it is possible to prevent the mixing of foreign matter caused by the grinding shavings attached to the raw material and other undesirable conditions.

<Method for manufacturing recycled casting>

In a method for manufacturing a regenerated casting in one embodiment of the present invention, a target material that has been cleaned by the target material grinding method can be used as a raw material for casting to manufacture a regenerated casting. In this way, a regenerated casting with less impurities (bonding material) can be manufactured. The regenerated casting is also called a slab or an ingot, and the target material 2 can be manufactured again from the casting.

As a method for manufacturing a regenerated casting, any method known to a person skilled in the art can be used. For example, it can be manufactured through the steps of melting and casting. As a melting method, an electric furnace or a combustion furnace can be used to melt the cleaned target material in the atmosphere or in a vacuum. As a casting method, continuous casting, semi-continuous casting, mold casting, precision casting, hot top casting, gravity casting, etc. can be used. In addition, degassing treatment and impurity removal treatment can also be performed between the melting and casting steps.

The manufacturing conditions, especially the temperature, of the regenerated casting can be appropriately determined according to the metal mainly contained in the target. For example, when the metal contained as the main component in the target is aluminum, first, the target cleaned by the method of the embodiment is melted in a crucible of carbon or alumina at a temperature of 670°C to 1200°C, preferably 750°C to 850°C, under vacuum (e.g., 0.03 Torr) or in the atmosphere. Then, after stirring in the atmosphere and removing scum as needed, it is cooled in the atmosphere, thereby manufacturing the regenerated casting.

For example, when the metal contained as the main component in the target is copper, the cleaned target is melted in a crucible of carbon or alumina under vacuum (e.g., 0.03 Torr) or in the atmosphere at a temperature of 1100°C to 1500°C, preferably 1150°C to 1200°C, and stirred in the atmosphere as necessary to remove scum, and then cooled in the atmosphere, thereby producing a regenerated ingot.

In the production of the regenerated casting, it can be produced only by using the target material cleaned by the method of the embodiment, or a mixture of the original raw material metal and the cleaned target material can be used. When the raw material metal and the cleaned target material are mixed, the mixing ratio of the cleaned target material can usually be 20% by mass or more. From the perspective of suppressing the ratio of raw material costs in the manufacturing cost, it is preferably 50% by mass or more.

<Recycled casting block>

The regenerated casting of this embodiment is manufactured by casting a target material cleaned by the method of the embodiment as a raw material, so as described above, the impurities originating from the bonding material and the supporting member constituting the bonding layer are fully removed, that is, the elements contained in these impurities are substantially not contained, and the composition is substantially the same as the original (unused) target material. Therefore, a target material having substantially the same composition as the original target material can be manufactured again from such a regenerated casting.

In this specification, "having substantially the same composition as the original (unused) target" means that the main component metal is the same and the target may contain impurities of the same amount as the impurities originally contained in the original target. For example, the total amount of impurities originating from the bonding material and the supporting member constituting the bonding layer or the metallization layer can be less than 10ppm on a mass basis, preferably 0.1ppm or more and 8ppm or less, more preferably 0.1ppm or more and 6ppm or less, further preferably 0.1ppm or more and 5ppm or less, further preferably 0.1ppm or more and 4ppm or less, and the total amount of all impurities (i.e., the sum of the amount of impurities originally contained in the original target material and the total amount of impurities originating from the bonding material and the supporting member) can be less than 50ppm, preferably 0.1ppm or more and 20ppm or less, more preferably 0.1ppm or more and 10ppm or less, further preferably 8ppm or less (or less than 8ppm), further preferably 0.1ppm or more and 8ppm or less.

Furthermore, the impurities originally contained in the original target material and their amount 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 regenerated casting can also be used for purposes other than target materials. For example, it can also 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 supporting member constituting the bonding layer contained in the regenerated casting of the present embodiment is less than 10 ppm on a mass basis, preferably 0.1 ppm or more and 8 ppm or less, more preferably 0.1 ppm or more and 6 ppm or less, further preferably 0.1 ppm or more and 5 ppm or less, further preferably 0.1 ppm or more and 4 ppm or less, and particularly preferably 0.3 ppm or more and 2 ppm or less. For example, if the total amount of Cu, In, Sn and Zn is within the above range, the crystal grains of the regenerated casting can be refined without causing a decrease in the conductivity of the regenerated casting. As a result, the crystal grains of the target material produced by the recycled casting also become fine, so a target material with excellent sputtering characteristics can be produced. In addition, if Cu, In, Sn or Zn with an atomic weight larger than aluminum is contained within the above range, the electromigration resistance of the aluminum thin film produced by sputtering the target material produced by the recycled casting can also be improved.

The amount of impurities from the bonding material and the supporting member contained in the regenerated casting of this embodiment is extremely small, so it can be measured using Glow Discharge Mass Spectrometry (GDMS). Specifically, in this specification, the amount of impurities is set to be measured using VG9000 manufactured by VG Elemental. The quantitative lower limit of GDMS varies depending on the main element of the target and the element as the detection object. For example, when the metal contained as the main component of the target is aluminum, it is usually 0.001 ppm or more and 0.1 ppm or less on a mass basis, for example, 0.01 ppm in the case of In.

Although it depends on the application, it is known that, for example, aluminum targets for flat panel displays may generally 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. Therefore, if the amount of impurities in the regenerated casting of this embodiment is within the above range, there is no particular hindrance to sputtering.

In addition, in the present invention, since the target is cleaned by grinding, the abrasive grains of the grinding material can be left on the target intentionally. By grinding the target with a grinding material having abrasive grains of a different composition from the main component of the target, a target can be manufactured in which abrasive grains of a trace amount of an additive element are attached to the surface when the target is melted. When the target material is a high-purity metal, preferably aluminum with a purity of 99.99% (4N) or more, more preferably aluminum with a purity of 99.999% (5N) or more, or copper with a purity of 99.99% (4N) or more, when a regenerated casting is obtained from the cleaned target material, the extremely small amount of additive elements derived from the abrasive particles contained in the target material can miniaturize the crystal grain size of the regenerated casting without deteriorating the electrical conductivity of the pure metal, thereby achieving miniaturization of the crystal grains of the target material manufactured from the regenerated casting, and obtaining a target material with excellent sputtering properties. From the viewpoint of preventing the deterioration of the conductivity of the regenerated casting and making the grain size of the regenerated casting finer, the content of the element derived from the abrasive grains of the abrasive material contained in the regenerated casting is preferably 0.5 ppm or more and less than 10 ppm, more preferably 1 ppm or more and less than 10 ppm, further preferably 2 ppm or more and less than 8 ppm, and particularly preferably 2.5 ppm or more and less than 6 ppm. For example, when the target material is aluminum with a purity of 99.999% (5N) or more and the element derived from the abrasive grains of the abrasive material is Si, a regenerated casting of aluminum containing a small amount of Si can be obtained. The aluminum thin film formed by sputtering a target made from the regenerated casting and forming a film on a silicon wafer or a glass substrate can suppress the diffusion of Si from the substrate to the thin film, thereby preventing the degradation of the characteristics of the aluminum thin film due to excessive Si diffusion.

In addition, from the perspective of forming a metal thin film with excellent properties, especially an aluminum thin film, the regenerated casting preferably 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 of 2 ppm or more and 8 ppm or less.

Thus, according to the present invention, the used target material can be simply and fully cleaned, and the cleaned target material substantially does not contain impurities derived from the bonding material and the supporting member, so that a regenerated casting can be manufactured and the target material can be simply regenerated.

Furthermore, the present invention is not limited to the above-mentioned implementation forms, and design changes can be made within the scope of the subject matter of the present invention.

In the above-mentioned embodiment, the grinding material is set in a belt shape and the bonding surface of the target material is ground while the grinding material is rotated, but the grinding material can also be set in a plane shape and the bonding surface of the target material is ground while the grinding material is moved in the horizontal direction. That is, the grinding material only needs to include a plurality of blocks including grinding stones and the plurality of blocks are arranged on the same surface in a manner that the adjacent blocks are separated by gaps.

(Implementation Example 1)

By heating the bonding layer of the used sputtering target (280°C), the sputtering target is separated into the target material and the supporting member (support plate).

Furthermore, the sputtering target before use is made by bonding an aluminum flat target (purity: 99.999%, Vickers hardness: 16, size: 2000mm×200mm×15mm) and an oxygen-free copper support member (purity: 99.99%, size: 2300mm×250mm×15mm) using an In solder material (solder layer thickness: 350μm) (Sn-Zn-In solder material is used when metallizing the target).

Furthermore, use a silicone scraper to scrape off the solder material attached to the bonding surface of the separated target and remove as much solder material as possible. After the self-sputtering target is separated, cut the target into pieces of about 200mm×100mm×15mm.

A grinding material was prepared, wherein a block (resinoid grinding stone made by bonding silicon carbide with a particle size of F120 in JIS R 6001-1:2017 with phenolic resin) having a parallelogram shape (in a top view) with a grinding surface roughness Ra of 20 μm, an average height of 3 mm, an average length of 16 mm on the long side, and an average length of 14 mm on the short side was attached to a grinding cloth body (cotton-polyester blended cloth, resin cured material, carbon black mixture) at an average separation distance of 0.5 mm and tilted 72 degrees with respect to the grinding direction (rotation direction of the belt sander). The corners (periphery) of the block were C-chamfered at 1.25 mm, and the size of the grinding material was set to 60 mm×260 mm. After fixing both ends of the abrasive material into a belt shape, it was mounted on a belt sander (RMB-E manufactured by Office Mine Co., Ltd., with a contact wheel (roller) being a sponge contact M (Φ50mm×width 60mm) manufactured by Office Mine Co., Ltd.), and the entire bonding surface of the cut target material was evenly polished for 30 seconds (processing speed ^400cm2 /min). The surface roughness Ra (arithmetic mean roughness) of the abrasive material was measured in accordance with JIS B0601:2001 using a small surface roughness meter Surftest SJ-301 manufactured by Mitutoyo Co., Ltd. (Ra measurement range 0.01μm~100μm).

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

<Analysis conditions>

X-ray irradiation diameter: 10mmΦ

Excitation voltage: 10kV (Na~Sc), 50kV (Ti~U)

Current: 100μA

Measurement time: 200 seconds (measured for 100 seconds at each excitation voltage)

Environment: He

Tube ball: Rh target

Filter: None

Measurement method: fundamental parameter method

Detector: Si(Li) semiconductor detector

Furthermore, if the joint surface of the used target material before cleaning is analyzed by EDXRF in the same manner as described above, Sn, Zn, and In derived from the solder material are present at less than 10 wt%, less than 10 wt%, and 1 wt% to 70 wt%, respectively, and Cu derived from the support member is present at 1 wt% to 50 wt%. Compared with the analysis results before cleaning, the analysis results of the joint surface after cleaning based on the grinding treatment and the presence or absence of visual clogging on the surface of the grinding material after the grinding treatment are used as the treatment results, and are classified and evaluated as A (significant removal of impurities and no obvious clogging of the grinding material), B (sufficient removal of impurities and no obvious clogging of the grinding material), and E (the amount of each impurity derived from the solder material or the support member detected exceeds 0.5wt%, or clogging of the grinding material is confirmed). The evaluation results are shown in Table 1 below (unit: mass % (wt%)). In addition, for the elements of the components of the bonding materials or supporting members that were not detected, it was also confirmed whether the X-ray peak was detected.

(Example 2)

The grinding material used was a slash ring with a particle size of #220 (manufactured by Sankyo Chemical Co., Ltd., hardness M, and the main abrasive grains were aluminum oxide). The grinding operation was performed in the same manner as in Example 1. In addition, regarding the grinding material used, the corners were not chamfered, the grinding surface was a rhombus with one side of 12 mm, the surface roughness Ra of the grinding surface was 10 μm, the average height of the blocks was 9 mm, and the average separation distance between the blocks was 0.7 mm. In addition, the grinding stone was installed on the belt sander in a manner such that the inclination of the grinding stone was 75° relative to the grinding direction (rotation direction of the belt sander). The evaluation results are shown in Table 1.

(Comparison Example 1)

The grinding material is a grinding cloth tape with a particle size of #240 (manufactured by Office Mine Co., Ltd., grinding cloth tape WA, the main abrasive grains are aluminum oxide). Other than this, the grinding operation is performed in the same manner as in Example 1. In addition, the grinding material used is not in a block shape, and the surface roughness Ra of the grinding surface is 17μm. The evaluation results are shown in Table 1.

(Comparison Example 2)

The grinding material used was HL belt with a particle size of #320 (manufactured by Office Mine Co., Ltd., with the main abrasive grains being aluminum oxide). The grinding operation was performed in the same manner as in Example 1. In addition, the grinding material used was not a block-shaped material, but a grinding material with abrasive grains bonded to a non-woven fabric. The evaluation results are shown in Table 1.

As can be seen from Table 1, in Example 1 and Example 2 using a grinding material with a block-shaped grinding stone, clogging of the grinding material was not confirmed, and impurities from the solder material or the supporting member were fully removed. In contrast, in Comparative Example 1 and Comparative Example 2 using a grinding material without a block-shaped grinding stone, clogging of the grinding material was confirmed, and impurities from the solder material or the supporting member could not be fully removed. Furthermore, the Al content in Example 1 is lower than that in Comparative Example 1, but it is within a range that is substantially not problematic. In addition, in Example 1, even in the initial stage of use of the grinding material, the contact between the grinding material and the bonding material attached to the surface of the target material is good, and grinding can be performed stably without generating vibrations during grinding, and impurities such as solder materials can be completely removed.

Furthermore, although not described in Table 1, when the abrasive material of Example 1 is used, impurities such as solder materials can be removed even if the grinding operation is repeated. On the other hand, when the abrasive material of Example 2 is used, no clogging is confirmed in the center of the grinding surface of the abrasive material during repeated grinding operations, but the solder material is observed to be attached to the sharp corners. Based on this situation, it is known that if the corners of the abrasive material are chamfered, even the relatively soft and sticky In is suppressed from adhering to the abrasive material, which is beneficial when used repeatedly. The use of the suitable abrasive material of the present invention is very effective in cleaning the target material for a large flat panel display with a large processing area by grinding, or in processing a large amount of target material.

(Implementation Example 3)

Using the same method as in Example 1, the sputter-plated target is separated into a supporting member (support plate) and a target material, and an aluminum target material of about 200mm×100mm×15mm is obtained.

The following polishing materials of conditions 1 to 4 were used as polishing materials. In addition, the bonding surface of the target material was cleaned by polishing in the same manner as in Example 1, and the bonding surface of the used target material after cleaning was subjected to EDXRF analysis. The evaluation results are shown in Table 2.

(Condition 1)

A grinding material was prepared, wherein a block (resin-type grinding stone in which silicon carbide with a particle size of F36 in JIS R 6001-1:2017 was bonded with phenolic resin) having a surface roughness Ra of greater than 100 μm, an average height of 3 mm, an average length of 16 mm on the long side, and an average length of 14 mm on the short side was bonded to a grinding cloth body (cotton-polyester blended cloth, resin cured material, carbon black mixture) with an average separation distance of 0.5 mm and a tilt of 15° relative to the vertical direction of the grinding direction (the direction perpendicular to the rotation direction of the belt sander) by mixing rubber. The corners of the block were C-chamfered at 1.25 mm, and the size of the grinding material was set to 60 mm×260 mm. The abrasive material is made by fixing both ends of the abrasive material in a strip shape.

(Condition 2)

A grinding material was prepared, wherein a block (resin-type grinding stone in which silicon carbide with a particle size of F60 in JIS R 6001-1:2017 was bonded with phenolic resin) having a parallelogram shape (in a top view) with a grinding surface roughness Ra of 31 μm, an average height of 3 mm, an average length of 16 mm on the long side, and an average length of 14 mm on the short side) was attached to a grinding cloth body (cotton-polyester blended cloth, resin cured material, carbon black mixture) with an average separation distance of 0.5 mm and an inclination of 15° relative to the grinding direction (the direction perpendicular to the rotation direction of the belt sander). The corners of the block were C-chamfered at 1.25 mm, and the size of the grinding material was set to 60 mm×260 mm. The abrasive material is made by fixing both ends of the abrasive material in a strip shape.

(Condition 3)

Use the same grinding material as in Example 1.

(Condition 4)

A grinding material was prepared, wherein a block (resin-type grinding stone in which silicon carbide with a particle size of F400 in JIS R 6001-2:2017 was bonded with phenolic resin) having a parallelogram shape (in a top view) with a grinding surface roughness Ra of 7.7 μm, an average height of 3 mm, an average length of 16 mm on the long side, and an average length of 14 mm on the short side) was attached to a grinding cloth body (cotton-polyester blended cloth, resin cured material, carbon black mixture) with an average separation distance of 0.5 mm and an inclination of 15° relative to the grinding direction (the direction perpendicular to the rotation direction of the belt sander) by mixing rubber. The corners of the block were C-chamfered at 1.25 mm, and the size of the grinding material was set to 60 mm×260 mm. The abrasive material is made by fixing both ends of the abrasive material in a strip shape.

Under any condition, no clogging was observed in the polishing material after polishing. As shown in Table 2, under any condition, impurities originating from the solder material or the supporting member were fully removed, and when the surface roughness Ra of the polishing material was 100 μm or less, the impurities originating from the solder material or the supporting member were reduced to a level of less than 0.1 wt%. In particular, when the surface roughness Ra of the polishing material was 20 μm, no impurities originating from the solder material or the supporting member were observed. In the case where the target material was aluminum, when the surface roughness of the polishing material was 31 μm or more, especially when it exceeded 100 μm, grooves or depressions were generated due to the intrusion of the polishing material into the target surface, and the solder material was pressed into the grooves or depressions, so that some impurities originating from the solder material and the supporting member were considered to remain. In addition, when the surface roughness Ra of the abrasive material is 7.7μm, the abrasive force is small, so it is believed that some impurities originating from the solder material remain on the target material.

(Implementation Example 4)

By heating the bonding layer of the used sputtering target (280°C), the sputtering target is separated into the target material and the supporting member (support plate).

Furthermore, the sputtering target before use is made by joining a flat target made of oxygen-free copper (purity: 99.99%, Vickers hardness: 90, size: 2000mm×200mm×15mm) and a supporting member made of oxygen-free copper (purity: 99.99%, size: 2300mm×250mm×15mm) using an In solder material (solder layer thickness: 350μm) (Sn-Zn-In solder material is used when metallizing the target).

Then, use a silicone scraper to scrape off the solder material attached to the joint surface of the separated target and remove as much solder material as possible. After separating from the supporting member, cut the target into pieces of about 100mm×45mm×15mm.

The target was made of oxygen-free copper and the processing speed was set to 15 cm ² /min. The bonding surface of the target was polished in the same manner as in Example 3, and the bonding surface of the used target after cleaning was analyzed by EDXRF.

Under any condition, no clogging was confirmed in the polishing material after polishing. As shown in Table 3, under any condition, impurities originating from the solder material or the supporting member were reduced. When the surface roughness Ra of the polishing material was 10 μm or more, the impurities originating from the solder material or the supporting member were reduced to a level less than 0.5 wt%. In particular, when the surface roughness Ra of the polishing material was 20 μm and 31 μm, no impurities originating from the solder material or the supporting member were confirmed. In the case of a target material of pure copper, when the surface roughness of the polishing material exceeded 100 μm, grooves or depressions were generated due to the intrusion of the polishing material into the target surface, and the solder material was pressed into the grooves or depressions, so that some impurities originating from the solder material and the supporting member remained. In addition, when the surface roughness Ra of the abrasive material is 7.7μm, the abrasive force is small, so it is believed that impurities derived from the solder material remain on the target material.

(Example 5)

Using the same method as in Example 1, the sputter-plated target is separated into a supporting member (support plate) and a target material, and an aluminum target material of about 200mm×100mm×15mm is obtained.

The processing speed was set to 480 cm ² /min, and the bonding surface of the target was polished by the same method as in Example 1 (Example 5-1), and the bonding surface of the used target after cleaning was analyzed by EDXRF; the contact wheel (roller) used a rubber contact body (hardness 55°, Φ55mm×width 60mm) manufactured by Office Mine (Co., Ltd.) and the processing speed was set to 480 cm ² /min. The bonding surface of the target was polished by the same method as in Example 1 (Example 5-2), and the bonding surface of the used target after cleaning was analyzed by EDXRF. The evaluation results are shown in Table 4. The "center" of the "evaluation position" refers to the center of the target, and the "end" of the "evaluation position" refers to the end of the target.

Under any condition, no clogging was confirmed in the polishing material after polishing. As can be seen from Table 4, under any condition, impurities originating from the solder material or the supporting member were fully removed, especially when a rubber roller (Example 5-2) was used, even if the processing speed was fast, impurities originating from the solder material or the supporting member were completely removed. Unlike a sponge roller, which is a soft raw material, a rubber roller is a hard raw material, so a further load can be applied for polishing, thereby polishing in a manner that the polishing material bites into the joint surface of the target material. Therefore, it is believed that the solder material is further removed.

(Implementation Example 6)

The bonding surface of the target was polished in the same manner as in Example 1 except that the processing speed was 200 cm ² /min, and the bonding surface of the used target after cleaning was subjected to EDXRF analysis.

(Implementation Example 7)

The target material was prepared by grinding the bonding surface of the target material in the same manner as in Example 1. Then, a grinding cloth belt with a particle size of #180 (manufactured by Office Mine Co., Ltd., grinding cloth belt WA, the main abrasive grains of which are aluminum oxide) was installed on the belt sander installed in Example 1, and the ground target material was further ground at a processing speed of 400 cm ² /min. The bonding surface of the used target material after cleaning was analyzed by EDXRF. The evaluation results are shown in Table 5.

A portion of the used target material obtained after cleaning in Example 6 and Example 7 is taken and dissolved at 850°C under vacuum (about 0.03 Torr) and cooled in the atmosphere to produce a regenerated casting.

The amount of impurities contained in the regenerated castings was analyzed using GDMS (VG Elemental, VG9000) for microanalysis of In, Sn, Zn, and Cu. The analysis results are shown in Table 6 below (unit: mass ppm (wt ppm)) together with the analysis results of unused targets as reference examples and castings made from used targets (before cleaning) using the same method.

As shown in Table 6, the total amount of impurities from solder materials (In, Sn, Zn) or supporting members (Cu) contained in the recycled castings produced in Examples 6 and 7 is less than 4 ppm on a mass basis. In addition, the total amount of impurities is also less than 10 ppm. In addition, as shown in Tables 5 and 6, by using abrasive grains with a composition close to that of the target material as the abrasive material, the risk of contamination caused by the abrasive material can be further reduced.

The above-mentioned embodiments and comparative examples describe a flat target material. The same results can be obtained by performing the same treatment on a cylindrical target material that is bonded to a support tube using a bonding material.

[Industrial availability]

According to the target grinding method of the present invention, the clogging of the grinding stone or grinding material can be reduced, and the impurities originating from the bonding material and the supporting member constituting the bonding layer can be reduced and removed from the target. Therefore, it is beneficial for the cleaning or regeneration of the used target.

2: Target material

2a: Splash coating

2b: Joint surface

10: Grinding tools

11: Main body

12: Grinding Department

13: Abrasive materials

15: First Roller

16: Second Roller

R: Arrow

Claims (11)

A regenerated casting ingot is a regenerated casting ingot derived from a sputtering target formed by bonding a target material mainly composed of metal and a supporting member using a bonding material, wherein the total amount of impurities from the bonding material and the supporting member is less than 10 ppm on a mass basis, and the Si content is greater than 2 ppm and less than 8 ppm. In the regenerated casting as described in claim 1, the Si content is the Si content of the abrasive grains derived from the abrasive material. In the regenerated casting as described in claim 1 or claim 2, the main component of the target material is aluminum. A method for manufacturing a target material, which is a method for manufacturing a target material constituting the regenerated casting block described in claim 1, the target material manufacturing method comprising: using an abrasive material to grind the bonding surface of a target material separated from a sputtering target formed by bonding the target material to a supporting member using a bonding material, the abrasive material comprising a plurality of blocks including grinding stones, and the plurality of blocks are arranged on the same surface in a manner of being separated from adjacent blocks with gaps therebetween, the Vickers hardness of the separated target material is greater than 10 and less than 40, and the surface roughness Ra of the blocks of the abrasive material is greater than 10 μm and less than 30 μm . A method for manufacturing a target material, which is a method for manufacturing a target material constituting a regenerated casting block as described in claim 1, the method comprising: using an abrasive material to grind the bonding surface of a target material separated from a sputtering target formed by bonding the target material to a supporting member using a bonding material, the abrasive material comprising a plurality of blocks including a grinding stone, and the plurality of blocks are arranged on the same surface in a manner separated from adjacent blocks by gaps, the Vickers hardness of the separated target material is greater than 40 and less than 120, and the surface roughness Ra of the block of the abrasive material is greater than 12μm and less than 50μm. A method for manufacturing a target material as described in claim 4 or claim 5, wherein the abrasive material is formed into a belt shape, and the bonding surface of the target material is polished while the abrasive material is rotated. The method for manufacturing a target material as described in claim 6, wherein the strip-shaped abrasive material is wound around a roller, and the roller is used to push the abrasive material onto the target material while grinding the bonding surface of the target material. A method for manufacturing a target material as described in claim 7, wherein the roller is a rubber roller. A method for manufacturing a target material as described in claim 4 or claim 5, wherein the main component of the separated target material is aluminum or copper. A method for manufacturing a target material as described in claim 4 or claim 5, wherein the bonding material is a solder material containing tin, zinc, indium, lead or an alloy of these metals. A method for manufacturing a regenerated casting block, comprising: using the target material obtained by the method for manufacturing a target material as described in claim 4 or claim 5 as a raw material for casting to manufacture a regenerated casting block.