JP2020132997A - Method for cleaning target material, method for manufacturing target material and method for manufacturing recycled ingot - Google Patents

Abstract

To provide a method for cleaning a target material, capable of simply and sufficiently removing impurities derived from a bonding material constituting a bonding layer and a support member from a used target material by blasting; a method for manufacturing the target material processed by the cleaning method; and a method for manufacturing a recycled ingot using the target material manufactured by the method as a raw material.SOLUTION: The method for cleaning a target material separated from a sputtering target formed by bonding a target material and a support member with a bonding material includes ejecting an abrasive material having a new Mohs hardness of 3 or more and a bulk density of 2 g/cmor less to a first surface bonding between the target material and the support member.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for cleaning a target material, a method for producing a target material to be treated by the cleaning 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 production 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 (soldering). 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.

Regarding the recycling of the sputtering target, for example, Patent Document 1 describes a method for removing surface deposits containing solder as a bonding material of a sputtering target by a chemical treatment such as an acid treatment or a treatment in which the chemical treatment is further combined with a blast treatment. Is disclosed.

Japanese Unexamined Patent Publication No. 2005-23350

The chemical treatment is a treatment for cleaning a used target material with an acid, a base, or the like. Such a process requires time and effort because it is necessary to immerse the used target material in a solution such as an acid or a base, for example. In addition, the thickness of the bonding material remaining on the used target material is mainly not uniform, and metal elements contained in support members such as backing plates and backing tubes are mixed into the target material by diffusion. In some cases. It takes time and effort to sufficiently remove impurities derived from the remaining bonding material and support member, which is particularly remarkable in a target material for a large-sized flat panel display.

The blasting process is a process of injecting (injecting and striking) an abrasive material (also called a projection material, a medium, a grinding material, etc.) onto a used target material. For example, it is a simple process because it can be performed mechanically using a dedicated blasting device or the like. As the abrasive, a material made of metal or ceramics is generally used. However, the blasting must be done carefully, taking into account that the target material to be cleaned will be contaminated with abrasives. Therefore, it is difficult to inject the abrasive material in the blasting treatment under conditions that can sufficiently remove impurities derived from the bonding material and the support member on the surface of the target material. As a result, in the blasting process, impurities derived from the bonding material (for example, solder) and the support member remain on the surface of the target material, and it is not possible to obtain an ingot of the same quality as the original target material from the recovered material. It is difficult to regenerate a target material of the same quality as the original target material.

Under these circumstances, the blasting treatment is used in cleaning a used target material as an auxiliary treatment in combination with a chemical treatment or a treatment in finishing, for example, as described in Patent Document 1. However, if the above-mentioned chemical treatment is combined with the blast treatment, cleaning of the used target material takes more time and effort, which is complicated and costly. In addition, there is a risk that the remaining abrasive material further contaminates the target material from the state of the target material after the chemical treatment.

Therefore, the present invention is a method for cleaning a target material capable of easily and sufficiently removing impurities derived from a bonding material and a support member that constitute a bonding layer from a used target material by blasting, and a target by the cleaning method. It is an object of the present invention to provide a production method including cleaning a material, and a method for producing a recycled ingot using a target material obtained by the production method as a raw material.

According to the first gist of the present invention, it is a method of cleaning a target material separated from a sputtering target formed by joining a target material and a support member with a joining material.
Injecting an abrasive having a new Mohs hardness of 3 or more and a bulk specific gravity of 2 g / cm ³ or less onto the first surface of the target material to which the target material and the support member are joined. including,
A method of cleaning the target material is provided.

In one embodiment of the present invention, the value obtained by multiplying the new Mohs hardness of the abrasive and the particle size (μm) of the abrasive can be 1100 or more and 6500 or less.

In one embodiment of the present invention, the bulk specific gravity of the abrasive may be 0.5 g / cm ³ or more and 1.7 g / cm ³ or less.

In one embodiment of the present invention, the new Mohs hardness of the abrasive may be 12 or less.

In one aspect of the invention, the abrasive can be organic.

In one embodiment of the present invention, the abrasive can be sprayed at an angle of 30 ° or more and 60 ° or less with respect to the first surface.

In one embodiment of the present invention, the Vickers hardness of the target material can be 100 or less.

In one embodiment of the present invention, the main component of the target material may be aluminum.

In one embodiment of the invention, the bonding material can be a solder containing an alloy of tin, zinc, indium, lead or metals thereof.

According to the second gist of the present invention, there is provided a method for producing a target material (or a used target material), which comprises treating the target material by the method of the first gist of the present invention.

According to the third gist of the present invention, there is a method for producing a recycled ingot, which comprises casting the target material obtained by the manufacturing method of the second gist of the present invention as a raw material to produce a recycled ingot. Provided.

In the cleaning method of the target material of the present invention, impurities derived from the bonding material and the support member constituting the bonding layer can be easily and sufficiently removed from the used target material by the blasting treatment, and the cleaning method is used. A method for producing a target material and a method for producing a recycled ingot using the target material obtained by the method as a raw material can be provided.

It is the schematic of the manufacturing process for manufacturing a sputtering target. It is sectional drawing which shows one example of the structure of the sputtering target which concerns on this invention. It is sectional drawing which shows another example of the structure of the sputtering target which concerns on this invention. It is sectional drawing of the joint surface which separated the target material from the sputtering target in one embodiment when the target material is a flat plate type. It is sectional drawing which shows the angle which the abrasive material is ejected with respect to the 1st surface which a target material and a support member were joined in one Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to drawings and the like, but the present invention is not limited to such embodiments.

The manufacturing process for manufacturing the sputtering target will be briefly described. As shown in the schematic view of FIG. 1, first, in general, the metal is melted and the ingot obtained by casting is processed (for example, the obtained ingot is subjected to plastic working such as rolling and extrusion, and then cutting. Machining such as polishing) is performed to produce a target material having a shape such as a flat plate type or a cylindrical type. Next, a sputtering target can be produced by joining the target material to a separately produced support member such as a backing plate or a backing tube using a bonding material. As will be described in detail below, the sputtering target is separated into a target material and a support member after being used in sputtering. After that, the used target material is cleaned by blasting to remove impurities (hereinafter, also referred to as joint material) derived from the joint material and the support member forming the joint layer, and melted and cast to form a recycled ingot. Can be. By processing this recycled ingot, the target material can be manufactured again.

<How to clean the target material>
The method for cleaning the target material according to one embodiment of the present invention is a method for cleaning the target material separated from the sputtering target formed by joining the target material and the support member with the bonding material, and the target material. This includes injecting an abrasive having a new Mohs hardness of 3 or more and a bulk specific gravity of 2 g / cm ³ or less onto the first surface to which the target material and the support member have been joined. In the present specification, the process of injecting an abrasive material onto the target material separated from the sputtering target may be referred to as cleaning.

First, a configuration example of the sputtering target according to the present invention will be described.

In the present invention, the "sputtering target" is a material obtained 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, and the like. Etc. are not particularly limited. When the sputtering target is a flat plate type, a flat plate type 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.

FIG. 2 is a cross-sectional view showing one example of the configuration of the sputtering target according to the present invention. As shown in FIG. 2, the sputtering target 10 is composed of a target material 1 mainly composed of metal, a support member 2, and a bonding layer 3 composed of a bonding material.

The target material 1 can be mainly composed of a metal. For example, the target material 1 is selected from the group consisting of aluminum, copper, chromium, iron, tantalum, titanium, zirconium, tungsten, molybdenum, niobium, silver, cobalt, ruthenium, platinum, palladium, gold, rhodium, iridium and nickel. It may be an alloy containing at least one metal selected from the above group.

The Vickers hardness of the target material 1 is preferably 100 or less, more preferably 10 or more and 50 or less, still more preferably 11 or more and 40 or less, still more preferably 12 or more and 30 or less, and particularly preferably 13 or more and 20 or less. When the cleaning method of the present embodiment is applied to the target material 1 having such a Vickers hardness range, it is possible to more preferably remove the bonding material or the like because the compatibility with the abrasive material described later is good. The Vickers hardness can be confirmed by the Vickers hardness test (JIS Z 2244: 2003).

The main component of the target material 1 is preferably aluminum (purity 99.99% (4N) or higher, preferably purity 99.999% (5N) or higher) or copper (purity 99.99% (4N) or higher). .. In particular, when the main component of the target material 1 is aluminum, the bonding material and the like can be removed more preferably. There are no particular restrictions on the dimensions, shape and structure of the target material 1. As the target material 1, a flat plate type or a cylindrical type can be used.

When the target material 1 is a flat plate type, the dimensions of the target material 1 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 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 1 has a cylindrical shape, the dimensions of the target material 1 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 1 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 1 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 the target material 1 for a large flat panel display can be easily processed.

When the support member 2 is a backing plate, it contains a metal selected from the group consisting of copper, chromium, aluminum, titanium, tungsten, molybdenum, tantalum, niobium, iron, cobalt and nickel, or is selected from the above group. It may be an alloy containing at least one kind of metal to be used. Preferably, it is copper (oxygen-free copper), a chromium copper alloy or an aluminum alloy. The size, shape and structure of the backing plate are not particularly limited as long as they are plate-shaped on which the target material 1 can be placed. On the other hand, when the support member 2 is a backing tube, the constituent metal contains the same metal as when the support member 2 is a backing plate, but among them, stainless steel (SUS), titanium, titanium alloy or the like. Is preferable. The dimensions of the backing tube are usually longer than the cylindrical target material because they are inserted and joined inside the cylindrical target material, and the outer diameter of the backing tube is preferably slightly smaller than the inner diameter of the cylindrical target material. ..

The joining material constituting the joining layer 3 is not limited as long as it is used for joining the target material 1 and the support member 2 and can be used for forming the sputtering target 10. The joining material includes, for example, solder, brazing material and the like.

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

The brazing material can join the target material 1 and the support member 2, and can be used without particular limitation as long as it is a metal or alloy having a melting point lower than that of the target material 1 and the support member 2.

As the bonding material, it is preferable to use solder such as In or In alloy, Sn or Sn alloy, which generally has a low melting point. When the cleaning method of this embodiment is applied when the solder as described above is used as the bonding material, the bonding material or the like can be removed more preferably because the compatibility with the abrasive material described later is good.

By heating, the solder forms a diffusion layer (alloy layer) with the metal contained in the target material 1 on the bonding surface with the target material 1, whereby the target material 1 and the solder can be bonded. Alternatively, the solder also forms a diffusion layer (alloy layer) with the metal contained in the support member 2 on the joint surface with the support member 2, whereby the support member 2 and the solder can be bonded. Therefore, by using such solder, a solder layer can be formed as the bonding layer 3 and the target material 1 and the support member 2 can be bonded.

In general, simply placing the above-mentioned solder on the target material 1 and the support member 2 and melting the solder does not affect the oxide film that may exist on the surface of the target material 1 and the support member 2, and sufficient bonding strength cannot be obtained. There is. FIG. 3 is a cross-sectional view showing another example of the configuration of the sputtering target according to the present invention. As shown in FIG. 3, in the other sputtering target 10, in order to improve the wettability of the solder with respect to the surfaces of the target material 1 and the support member 2 and obtain sufficient bonding strength, the bonding layer 3 is used. The solder layer 3a and the metallized layers 3b and 3b'are provided.

"Metallizing" is a treatment method that can generally be used to form a metal film on a non-metallic surface. The metallized layers 3b and 3b'can be formed on the target material 1 or the support member 2 by using, for example, metallizing solder. The metallized layers 3b and 3b'are formed by, for example, using an ultrasonic soldering iron to heat the oxide film of the target material 1 or the support member 2 while breaking it by the vibration energy (cavitation effect) of ultrasonic waves. Can be done. Specifically, it can be formed by chemically bonding the metal atoms contained in the metallizing solder and the metal atoms contained in the target material 1 or the support member 2 together with the oxygen atoms in the oxide film.

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 1 or the support member 2 may be appropriately selected.

The metallized layers 3b and 3b'can also be bonded to the solder layer 3a, and are located between the target material 1 and the solder layer 3a or between the support member 2 and the solder layer 3a, respectively, with the target material 1. It can play a role of firmly bonding the bonding layer 3 and the support member 2 to the bonding layer 3.

In the present specification, the bonding layer 3 includes not only a layer composed of bonding materials such as solder and brazing material as shown in FIG. 2, but also at least one of metallized layers 3b and 3b'as shown in FIG. It also includes the including layer.

The thickness of the solder layer 3a can be, for example, 50 μm or more and 500 μm or less when the support member 2 is a flat plate type, and can be, for example, 250 μm or more and 1500 μm or less when the support member 2 is a cylindrical type. The thickness of the metallized layers 3b and 3b'can be in the range of, for example, 1 μm or more and 100 μm or less when the support member 2 is both a flat plate type and a cylindrical type.

After the sputtering target 10 is used in sputtering, the target material 1 is separated (or peeled off) from the sputtering target 10 as shown in the schematic view of FIG. The method for separating the target material 1 from the sputtering target 10 is not particularly limited. For example, heat (for example, 180 ° C. or higher and 300 ° C. or lower) is applied to the joint layer 3 to soften or melt the joint layer 3 and physically destroy the joint layer 3 as necessary to sputter the target material 1. It can be separated from 10.

FIG. 4 is a cross-sectional view of a joint surface in which the target material in one embodiment when the target material is a flat plate type is separated from the sputtering target. As shown in FIG. 4, in the target material 1 after separation, the surface (that is, sometimes referred to as the first surface 100 or the “joining surface”) bonded to the backing plate is covered with the metallized layer 3b described above. And 3b', at least a part of the bonding layer 3 is attached and remains. In some cases, not only the bonding layer 3 but also impurities derived from the backing plate may be diffused and remain on the surface of the bonding layer 3 and the target material 1 on the bonding surface side.

Preferably, before injecting the abrasive in cleaning the target material 1, the bonding layer 3 adhering to the first surface 100 after separation is previously as much as possible using a spatula (for example, a spatula made of silicone) or the like. Scratch it off. It is difficult to completely remove the bonding material adhering to the first surface 100 after separation by scraping in advance with a spatula or the like, and in particular, the metallized layer 3b firmly bonded to the target material 1 cannot be removed. .. Further, the bonding material may adhere and remain on the sputtering surface and the side surface of the target material 1. The causes are, for example, that the bonded material melted during the separation of the target material 1 adheres to the sputtering surface and the side surface, and that the separated used target materials 1 are stacked and stored, so that the bonding surface and the sputtering are performed. Examples thereof include contact with the surface and the side surface, and the bonding material of the bonding surface adheres to the sputtering surface and the side surface. Therefore, the cleaning method of the present invention may be applied to the sputtering 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 by 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 cleaning 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, a 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 cleaning 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 2 to the target material, the metal element can be similarly confirmed by EDXRF. In addition, Wavelength Dispersive X-ray Fluorescence Analysis (WDXRF), Electron Probe Micro Analysis (EPMA), Auger Electron Spectroscopy (AES), X X-ray Photoelectron Spectroscopy (XPS), Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS), Laser Inductively Coupled Plasma Mass Spectroscopy (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 2 can be confirmed, but analysis is possible. 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.

As described above, in the method for cleaning the target material, at least the abrasive material is sprayed onto the first surface 100 where the target material 1 and the support member 2 of the target material are joined.

The abrasive is not particularly limited as long as it has a new Mohs hardness of 3 or more and a bulk specific gravity of 2 g / cm ³ or less. Preferably, the abrasive is one that does not contaminate the target material when sprayed onto the first surface 100. If the target material is contaminated during injection, components derived from the abrasive material will be mixed in as impurities, and it may be difficult to regenerate the target material of the same quality as the original target material from the recovered material. is there.

Examples of abrasives having a new moth hardness of 3 or more and a bulk specific gravity of 2 g / cm ³ or less include metals such as aluminum, alloys containing the metals, ceramics such as alumina, cerium oxide, glass, and silica sand, and non-metals. Examples include metals and organic compounds such as plant species and resins. In the present specification, the term "organic substance" includes the intention of an organic compound, is a compound containing carbon, and also means a substance represented by a composition containing oxygen, nitrogen, hydrogen, and the like.

Specific examples of these abrasives include aluminum (for example, pure aluminum cut wire and alloy aluminum cut wire manufactured by Sansho Abrasive Co., Ltd.) as metals and alloys. Examples of ceramics and non-metals include alumina (for example, Fujirandom A and Fujirandom WA manufactured by Fuji Manufacturing Co., Ltd., Type WA (white molten alumina) manufactured by IKK Shot Co., Ltd., and brown color manufactured by Shinto Kogyo Co., Ltd. Fused alumina projecting material (A), white molten alumina projecting material (WA), etc.), silicon carbide (for example, Fujirandom C and Fujirandom GC manufactured by Fuji Manufacturing Co., Ltd., Type C manufactured by IKK Shot Co., Ltd.) (Black silicon carbide), etc.), glass (for example, Fuji glass beads and Fuji glass powder manufactured by Fuji Seisakusho Co., Ltd., glass beads (GB) and glass powder (GP) manufactured by Shinto Kogyo Co., Ltd.), Emery (for example, Tosa Emery Extra manufactured by Fuji Seisakusho Co., Ltd.), silica sand (for example, silica sand manufactured by Nichu Co., Ltd.), glassy molten black sand (for example, black grit manufactured by KM Material Co., Ltd.), etc. Be done. As the resin, melamine resin (for example, Polyplus (type III) manufactured by Fuji Seisakusho Co., Ltd., Shave Media M, Type XH (melamine resin blast material) manufactured by IKK Shot Co., Ltd., and Shinto Kogyo Co., Ltd. Plastic Shot PSM, Miracle Media MM-M manufactured by Hieda Chemical Industry Co., Ltd.), Uria Resin (For example, Shave Media Y and Polyplus manufactured by Fuji Seisakusho Co., Ltd., Type H (Uria Resin) manufactured by IKK Shot Co., Ltd. Blast material), plastic shot PSU manufactured by Shinto Kogyo Co., Ltd., Miracle Media MM-U manufactured by Hieda Chemical Industry Co., Ltd.), unsaturated polyester resin (for example, poly extra manufactured by Fuji Seisakusho Co., Ltd., Hieda) Examples thereof include miracle media MM-PE manufactured by Kagaku Kogyo Co., Ltd.), acrylic resin (for example, miracle media MM-A manufactured by Hieda Kagaku Kogyo Co., Ltd.) and the like. Plant species include peach seeds (for example, peach manufactured by Fuji Seisakusho Co., Ltd., peach shot PS manufactured by Shinto Kogyo Co., Ltd.), apricot seeds (for example, apricots manufactured by Fuji Seisakusho Co., Ltd., new). Examples include apricot shot AP manufactured by Toko Kogyo Co., Ltd.), walnut (for example, walnut manufactured by Fuji Seisakusho Co., Ltd., walnut shot KS manufactured by Shinto Kogyo Co., Ltd.) and the like.

Among these abrasives, alumina is preferable as an organic substance (plant species, resin, etc.) and ceramics as a material that does not easily contaminate the target material 1 during cleaning. Further, organic substances are more preferable because they have durability of the abrasive when used repeatedly. Further, even if the abrasive material made of an organic substance remains on the surface of the target material 1, it is preferable because it has an advantage that it is removed in a casting step after cleaning the target material, for example.

The new Mohs hardness is synonymous with the modified Mohs hardness. The new Mohs hardness is a measure of hardness for determining the hardness of minerals by comparing with 15 kinds of standard minerals. The reference minerals are soft (new Mohs hardness 1) to hard (new Mohs hardness 15) in this order: talc, gypsum, square stone, fluorite, apatite, regular length stone, molten quartz, crystal (quartz), topaz (quartz). Topaz), fluorite, molten zirconia, molten alumina, silicon carbide, boron carbide and diamond. In the present specification, the new Mohs hardness is measured by rubbing a sample substance (abrasive material) whose hardness is to be measured with these reference minerals and checking the presence or absence of scratches. For example, if calcite is not scratched and fluorite is scratched, the new Mohs hardness of the sample substance (abrasive) is 3.5 (meaning between 3 and 4).

When a polishing material having a new Mohs hardness of 3 or more is used, the hardness of the polishing material is sufficient, so that impurities derived from the bonding material and the support member 2 constituting the bonding layer 3 can be sufficiently removed by injection. Preferably, the new Mohs hardness of the abrasive is 3 or more and 12 or less. Examples of the abrasive material having a new Mohs hardness of 3 or more and 12 or less include aluminum, copper, stainless steel (SUS), alumina, zircon, glass, and organic substances such as resins and plant species. If a new Mohs hardness of 12 or less is used, the abrasive has an appropriate hardness, so there is a risk that the target material 1 will be deeply scraped beyond the bonding layer 3 (or the metallized layer 3b if present). , The risk of sticking to the target material 1 and contaminating it can be reduced. From the viewpoint of the durability of the abrasive during repeated use, the new Mohs hardness of the abrasive is preferably 3 or more and 10 or less, more preferably 3 or more and 8 or more, and further preferably 3.5 or more and 5 or less.

When an abrasive material having a bulk specific gravity greater than 2 g / cm ³ is used, the bonding material or the like is pushed into the target material by the impact pressure of the polishing material, so that impurities derived from the bonding material and the support member 2 constituting the bonding layer 3 are used. Can not be sufficiently removed, and contamination can occur due to the abrasive material sticking into the target material. The bulk specific gravity (g / cm ³ ) of the abrasive material is preferably 0.1 g / cm ³ or more and 2 g / cm ³ or less, more preferably 0.3 g / cm ³ or more and 2.0 g / cm ³ or less, and further preferably 0. .5g / cm ³ or more 1.7 g / cm ³ or less, even more preferably 0.6 g / cm ³ or more 1.5 g / cm ³ or less, deliberately preferably 0.65 g / cm ³ or more 1.2 g / cm ³ or less Particularly preferably, it is 0.70 g / cm ³ or more and 1.0 g / cm ³ or less. In the present specification, "bulk specific gravity (g / cm ³ )" means the mass of a substance per unit apparent volume, and the mass is measured by naturally dropping the substance into a container whose volume is known and measuring the mass. Can be obtained by dividing by volume. The bulk specific density of the abrasive can be measured by a method according to JIS K 7365: 1999, JIS R 1628: 1997, or JIS Z 2504: 2012.

Abrasives having a bulk specific gravity of 2 g / cm ³ or less include, for example, ceramics such as silicon carbide, glass, silica sand, emery, and alumina, resins such as melamine resin, urea resin, and unsaturated polyester resin, peach seeds, and apricots. Examples include organic substances such as seeds and plant species such as walnuts. As described above, among these abrasives, from the viewpoint of high effect of preventing contamination of the target material by the abrasive during cleaning, alumina and organic substances such as resins and plant species are preferable, and organic substances are more preferable. is there.

Further, in the present invention, the value obtained by multiplying the new Mohs hardness of the abrasive and the particle size (μm) of the abrasive is predetermined after the abrasive satisfies the above-mentioned conditions of the new Mohs hardness and the bulk specific gravity. Within the range, it has been found that when the cleaning method of the present embodiment is used, the effect of removing impurities derived from the bonding material and the support member 2 constituting the bonding layer 3 from the target material 1 can be more preferably exhibited. It was. The predetermined range of the multiplied values is preferably 1100 or more and 6500 or less, more preferably 1200 or more and 5000 or less, still more preferably 1500 or more and 4500 or less, still more preferably 1800 or more and 4000 or less, and particularly preferably 2000 or more and 3500 or less. Is.

In the present specification, the "particle size (μm) (of the abrasive)" is the average value of a predetermined number of abrasives for the diameter of the circle when the projected image of the abrasive is approximated to a circle. .. The abrasive material for which the diameter is to be determined is randomly selected, and is preferably an average of 30 or more, more preferably 50 or more, still more preferably 100 or more. The projected image can be taken with an optical microscope or the like, and the diameter can be obtained by image analysis.

The method of injecting the abrasive is not particularly limited. Specifically, the above-mentioned abrasive material is jetted (sprayed and striked) with respect to the target surface, for example, the first surface 100 of the target material 1 shown in FIG. 4, preferably while maintaining a constant distance. ) Any method known to those skilled in the art may be used as long as it can be used. For example, a commercially available blasting device, particularly an air blasting device, can be used. Further, the abrasive material may be sprayed at the same location a plurality of times, preferably once or more and three times or less. Alternatively, when the processing width in one injection of the abrasive is smaller than a specific surface (first surface 100 of the target material 1), the abrasive may be injected by partially overlapping in a line shape or the like. Good.

The air blasting device is a device that injects and strikes an abrasive material on a specific surface by using air (compressed air) compressed by an air compressor (air compressor). For example, commercially available pneumatic blasters manufactured by Fuji Seisakusho Co., Ltd. (for example, SFK type, SGF type, SGK type, FDO-F type, SGO-F type, FD type, SG-BL type, etc.) are new. An air blasting device (MY series, eco-blaster series, etc.) manufactured by Toko Kogyo Co., Ltd., a shot blasting device, or the like can be used. As the nozzle head of the blasting device, a nozzle head having a nozzle diameter (for example, φ5 mm, φ6 mm, φ8 mm, etc.) and a shape suitable for the abrasive material to be used, the air compressor, and the processing area may be appropriately selected and used. Further, instead of the compressed air, a high-pressure gas such as nitrogen or argon may be used.

As for the blasting conditions, for example, when an air blasting device is used, the pressure of the compressed air is 0.2 MPa or more and 1.5 MPa or less, preferably 0.3 MPa or more and 1.2 MPa or less, more preferably 0.4 MPa or more and 1.1 MPa. Below, it is more preferably 0.5 MPa or more and 1.0 MPa or less. Under such pressure conditions of compressed air, for example, when the target material is aluminum, the processing speed is preferably 100 mm ² / min or more and 2000 mm ² / min or less, more preferably 200 mm ² / min or more and 1500 mm ² / min or less. It is even more preferably 250 mm ² / min or more and 1200 mm ² / min or less, even more preferably 300 mm ² / min or more and 1000 mm ² / min or less, and particularly preferably 400 mm ² / min or more and 800 mm ² / min or less. The treatment speed may be appropriately selected according to the pressure condition of the compressed air and the hardness of the target material 1 to be treated. However, if the pressure of the compressed air is too low or the processing speed is too fast, impurities derived from the bonding layer 3 (including the metallized layers 3b and 3b'if present) and the support member 2 made of the bonding material can be removed. The effect may not be sufficient. On the contrary, if the pressure of the compressed air is too high or the processing speed is too slow, the target material 1 itself is deeply scraped beyond the bonding layer 3 (including the metallized layer 3b if present), resulting in poor yield. Or, the bonding material may be pushed deeply into the target material 1 and the bonding material may remain.

In the method for cleaning the target material of the present embodiment, the angle at which the abrasive is sprayed is particularly long as long as the angle at which the abrasive hits the target surface, for example, the first surface 100 of the target material 1 shown in FIG. Not limited. FIG. 5 is a cross-sectional view showing an angle at which the abrasive material is sprayed onto the first surface where the target material and the support member are joined in one embodiment. As shown in FIG. 5, the abrasive material can be ejected from the nozzle head 4 at an angle θ with respect to the first surface 100 to which the target material 1 and the support member 2 are joined. Although only one nozzle head 4 is shown in FIG. 5, a plurality of nozzle heads may be used. The angle θ is preferably 15 ° or more and 90 ° or less, more preferably 20 ° or more and 70 ° or less, still more preferably 25 ° or more and 65 ° or less, still more preferably 25 ° or more and 55 ° or less, and particularly preferably 35 ° or more. It is 50 ° or less. This is because when the abrasive material is sprayed diagonally to the first surface 100 of the target material 1, the processing area is larger and the processing area is larger than when the abrasive material is sprayed from the vertical direction. This is because it is expected that the abrasive material that hits the surface escapes not only to the first surface 100 but also to the outside, and the effect of removing the bonding material and the like and cleaning is improved. Further, the injection at the above angle is particularly effective when the composition of the bonding material is a relatively soft metal such as In or Sn, or an alloy such as an In alloy or Sn alloy.

The vertical distance (or nozzle distance) between the tip of the nozzle head 4 and the target material 1 is, for example, 10 mm or more, preferably 12 mm or more and 100 mm or less, more preferably 15 mm or more and 70 mm or less, and further preferably 20 mm or more and 60 mm or less. Is. If the distance is too short, it may be affected by the abrasive material that bounces off the target material 1, and a sufficient cleaning effect may not be obtained. If the distance is too far, the impact when hitting the target material 1 is small. Therefore, a sufficient cleaning effect may not be obtained.

Conditions such as processing pressure, processing speed, injection angle θ, and nozzle distance are such that impurities derived from the bonding material and the support member 2 constituting the bonding layer 3 can be sufficiently removed from the used target material 1. In addition, it can be appropriately selected or adjusted according to the type and particle size of the abrasive and the type of the blasting device.

When the joint material and the metallized layer are sufficiently removed from the joint surface of the target material by cleaning, the surface after cleaning is roughened. When the surface is roughened, the specular reflectance of the surface after cleaning at a wavelength of 300 nm to 1500 nm is, for example, 1.0% or less. The specular reflectance is preferably 0.7% or less in order to confirm that impurities derived from the bonding material and the support member have been sufficiently removed. Further, the rate of change of the specular reflectance (the specular reflectance of the surface after cleaning / the specular reflectance of the surface before cleaning) with respect to the wavelength of each incident light at a wavelength of 300 nm to 1500 nm is preferably 0.025 or more and 0.85 or less. Is 0.05 or more and 0.75 or less, more preferably 0.08 or more and 0.60 or less, and further preferably 0.10 or more and 0.40 or less. It can be confirmed that the target material has been sufficiently removed, and it is possible to prevent the target material from being scraped too much.
The arithmetic mean roughness Ra of the surface of the target material after cleaning is 4 μm or more, and it is preferably 5 μm or more, more preferably 5 μm or more, in order to confirm that impurities derived from the bonding material and the support member are sufficiently removed. Is 6 μm or more. The rate of change in the arithmetic mean roughness Ra of the surface of the target material before and after cleaning (arithmetic mean roughness Ra of the surface after cleaning / arithmetic average roughness Ra of the surface before cleaning) is preferably 3 or more, more preferably 4. The cleaning treatment may be carried out so as to be 20 or more, more preferably 5 or more and 10 or less. Usually, the arithmetic mean roughness Ra of the surface of the target material after cleaning is 50 μm or less, preferably 30 μm or less. If the arithmetic mean roughness Ra of the surface of the target material after cleaning is too large, foreign substances such as dust and sand are likely to adhere, and the thickness of the oxide film becomes thick, which may increase impurities in the recycled ingot. is there.

According to the method for cleaning the target material of the present embodiment, the balance between the new Mohs hardness and the bulk specific density of the abrasive material is excellent, so that the used target material 1 to the bonding layer 3 (metallize if present) are used only by the blasting treatment. Impurities derived from the bonding material and the support member 2 constituting the layers 3b and 3b') can be easily and sufficiently removed. In the present specification, "sufficiently removing" means that at least on the first surface 100 where the target material 1 and the support member 2 are bonded, the lower limit of EDXRF detection (for example, under the detection of impurities derived from the bonding material). The limit is smaller than about 0.01% by mass), and the elements contained in the impurities derived from the bonding material (including the metallized layers 3b and 3b'if any) constituting the bonding layer 3 to the extent that it cannot be detected by EDXRF. It means that the amount of the element and the amount of the element contained in the impurity derived from the support member 2 are 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 cleaning the target material according to the above-described embodiment. As shown in the schematic view of FIG. 1, the target material subjected to such treatment can be used for 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 cleaning method for the target material but also other treatments. For example, it may include a process for removing abrasives and polishing debris adhering to the used target material after cleaning (for example, blowing high-pressure air or cleaning with running water). By removing the abrasive material and polishing debris, it is possible to prevent problems such as foreign matter contamination caused by the abrasive material and polishing debris adhering to the raw material when melting and casting the used target material after cleaning as a raw material. it can.

<Manufacturing method of recycled ingot>
In the method for producing a recycled ingot according to one embodiment of the present invention, as shown in the schematic view of FIG. 1, the target material obtained by the method for producing a target material (or used target material) according to the above-described embodiment is used. Includes casting as a raw material to produce recycled ingots.

As a method for producing a recycled ingot, 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 production conditions of the recycled ingot, particularly 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 washed 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>
The recycled ingot of one embodiment of the present invention is produced by the method of the above-described embodiment.

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 in the target material as a main component and the method for producing 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, and even more preferably 0.1 ppm or more and 4 ppm or less.

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.

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.

Examples and comparative examples of the present invention are shown below. The following embodiments of the examples and comparative examples of the present invention are merely examples, and do not limit the present invention in any way.

(Example 1)
In order to investigate what kind of abrasive can be used to remove impurities such as bonding materials, the used target material was blasted using various types of abrasives.

Aluminum flat target material (purity: 99.999%, Vickers hardness: 16, dimensions: 2000 mm x 200 mm x 15 mm) and oxygen-free copper backing plate (purity: 99.99%, dimensions: 2300 mm x 250 mm x 15 mm) and In solder (thickness of solder layer: 350 μm) were joined to prepare a sputtering target. Sn-Zn-In solder was used for metallizing the target material. The target material was separated from the backing plate by heating the sputtering target at 280 ° C. after using it for sputtering. The solder adhering to the joint surface (first surface) of the target material was scraped off with a silicone spatula to remove the solder as much as possible. After recovering the solder, the separated target material was cut to a size of about 50 mm × 50 mm × 15 mm.

A blast treatment was performed on the central portion of the joint surface (first surface) of the cut target material using a blasting device (SFK-2 type manufactured by Fuji Seisakusho Co., Ltd.). The processing conditions of the blasting device were a nozzle diameter of φ6 mm, a pressure of compressed air of 0.6 MPa, and an injection angle θ of 45 ° (an angle of 45 ° with respect to the first surface of the target material). Further, the vertical distance (nozzle distance) between the nozzle tip and the target joint surface was set to 30 mm. The maximum processing time is 15 seconds, the blasting position is fixed, and at 5 seconds (processing speed 1200 mm ² / min), 10 seconds (processing speed 600 mm ² / min), 15 seconds (processing speed 400 mm ² / min). The processing status of the target material was confirmed in.

As the abrasive, Fujirandom WA (manufactured by Fuji Seisakusho Co., Ltd .; material alumina) having a count of WA # 36 in Example 1-1 and Fujirandom WA (manufactured by Fuji Random WA Co., Ltd.) having a count of WA # 80 in Example 1-2. ) Made by Fuji Seisakusho; Material Alumina), Polyplus (Type III) with a count of TT # 30-40 in Example 1-3 (Manufactured by Fuji Seisakusho Co., Ltd .; Material Melamine Resin), Examples 1-4 to Implementation In Example 1-6, the counts are # 20-30, # 40, and # 60-80, respectively (manufactured by Fuji Seisakusho Co., Ltd .; material peach seed), and in Comparative Example 1-1, the counts are SUS304 # 80 stainless steel. Beads (manufactured by Fuji Seisakusho Co., Ltd .; material SUS304), in Comparative Example 1-2, Fuji Zircon beads with a count of FZB-40 (manufactured by Fuji Seisakusho Co., Ltd .; material Zircon), in Comparative Example 1-3 A cone with a count of # 20-40 (manufactured by Fuji Seisakusho Co., Ltd .; material corn cob) was used. As for Examples 2 and 3 described later, the same type of abrasive material and the same type of count were used as commercially available materials.

For the particle size (μm) of each abrasive, use KH-7700 manufactured by Hi-Rox Co., Ltd. to obtain the diameter of a circle when it approximates a circle from the projected image of about 100 particles for each abrasive. , Obtained by calculating the average value of the diameter.

The bulk specific gravity (g / cm ³ ) of each abrasive is such that the dry abrasive is naturally dropped into a measuring cylinder having a volume of 50 ml and filled, and the mass of the measuring cylinder is subtracted from the measured total mass to fill the filled abrasive. After determining the mass, the volume of the measuring cylinder was measured, and the mass of the abrasive was divided by the volume.

The type and material of each abrasive, the detailed intrinsic properties (shape and new Mohs hardness) of each abrasive, the particle size (μm) and bulk specific gravity (g / cm ³ ) obtained by the above method, and the new Mohs hardness. The values obtained by multiplying the particle size and the particle size are summarized in Table 1 below.

The joint surface (first surface) of the used target material after cleaning by blasting is analyzed using an EDXRF analyzer (EDX-700L manufactured by Shimadzu Corporation, detection limit: about 0.01% by mass in In). Semi-quantitative analysis). The analysis conditions are as shown below.
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: Helium Tube: Rh Target Filter: None Measurement method: Fundamental parameter method Detector: Si (Li) semiconductor detector

When the joint surface (first surface) of the used target material before cleaning was analyzed under the same conditions using the same device, Sn, Zn, and In derived from the solder (solder layer and metallized layer) were 10 respectively. It was present in an amount of 1% by mass or less, 10% by mass or less, and 1% by mass to 70% by mass. Cu derived from the backing plate was present in an amount of 1% by mass to 50% by mass. Compared with the analysis result before cleaning, the analysis result of the joint surface (first surface) after cleaning by blasting is used as the processing result, and A (impurities are remarkably removed (solder material and backing plate in 5 seconds processing time). (No impurities derived from)), B (Sufficiently remove impurities (No impurities derived from solder material or backing plate are detected in 15 seconds processing time)) and E (15 seconds processing can remove impurities) It was evaluated by classifying it into (not). The evaluation results of Examples 1-1 to 1-6 and Comparative Examples 1-1 to 1-3 for each type of abrasive are shown in Table 2 below (unit: mass% (wt%)). The details of the evaluation will be described later.

As shown in Table 2, in Examples 1-1 to 1-6, impurities such as solder could be sufficiently or remarkably removed. On the other hand, in Comparative Example 1-1 and Comparative Example 1-2, the SUS component and zirconium contained in the abrasive were detected, the abrasive was contaminated, and impurities such as solder could not be removed. In Comparative Examples 1-3, the cone as an abrasive was soft, and impurities such as solder could not be sufficiently removed.

From this result, if the new Mohs hardness of the abrasive is too small and too soft, or if the bulk specific density (g / cm ³ ) is larger than the predetermined value, the target material used in the blasting treatment is derived from the solder material and the backing plate. It turned out to be difficult to remove impurities.

Further, in Examples 1-2 to 1-5, impurities such as solder could be removed in a short time, so that the abrasive material had the above-mentioned new Mohs hardness and bulk specific gravity (g / cm ³ ) values. When the value obtained by multiplying the new Mohs hardness of the abrasive used in the blasting treatment and the particle size (μm) of the abrasive is within a predetermined range, impurities derived from solder or the like are present for a short time. It was found that it was removed efficiently.

Further, although not described in detail in Table 2, when the abrasives of Examples 1-3 to 1-5 are used, impurities such as solder are used even if cleaning is performed using the repeatedly used abrasives. Was able to be removed. On the other hand, in the case of using the abrasive of Example 1-2, it was confirmed that when cleaning was performed using the repeatedly used abrasive, a decrease in processing capacity presumed to be caused by cracking or chipping of alumina was confirmed. From this, for the abrasive, a value obtained by multiplying the above-mentioned new Mohs hardness and the bulk specific gravity (g / cm ³ ) and the above-mentioned new Mohs hardness and the particle size (μm) is predetermined. If the condition that the abrasive is within the range is satisfied and the abrasive is an organic substance (resin such as melamine resin and plant species such as peach seed in this embodiment), impurities are remarkably removed and the abrasive is abrasive. It has been found to be highly durable and beneficial for repeated use. The use of a suitable abrasive of the present invention is very effective when cleaning a target material for a large flat panel display having a large processing area or when processing a large amount of target material.

(Example 2)
In order to investigate the injection angle θ of the abrasive material suitable for removing impurities such as the bonding material, the abrasive material was injected from various angles to evaluate the impurity removal.

A test piece (50 mm × 50 mm × 15 mm) of the target material separated and cut was obtained by the same method as in Example 1 described above. A blasting device (SFK-2 type manufactured by Fuji Seisakusho Co., Ltd.) was used to blast the central portion of the joint surface of the target material. The processing conditions of the blasting device are a nozzle diameter of φ6 mm, a pressure of compressed air of 0.6 MPa or 0.9 MPa, a processing time of 5 seconds or 10 seconds, a fixed blasting position, and a processing speed of 600 mm ² /. Minutes, nozzle distance is 30 mm, injection angle θ is 30 °, 45 °, 60 ° or 90 ° (angle of 30 °, 45 °, 60 ° or 90 ° with respect to the first surface of the target material). did. As the abrasive, the abrasive used in Examples 1-3 and 1-5 was used.

The method of analyzing the joint surface (first surface) of the used target material after cleaning by the blast treatment and evaluating the treatment result is the same as in Example 1 described above, but in Example 2, A (impurities are remarkably removed). (No impurities derived from solder material or backing plate are detected in 5 seconds processing time)) and B (Sufficiently remove impurities (No impurities derived from solder material or backing plate are detected in 10 seconds processing time)) And C (In detected in a processing time of 10 seconds is 0.03 wt% or less) and evaluated. The evaluation results are shown in Table 3 below. The details of the evaluation will be described later.

As shown in Table 3, when the abrasive material is injected obliquely with respect to the joint surface (first surface) of the target material, particularly from an injection angle of 30 ° or more and 60 ° or less, the abrasive material is injected from the vertical direction. It was found that impurities derived from solder and the like were significantly removed as compared with the case of injecting.

(Example 3)
The amount of impurities contained in the recycled ingot was analyzed in order to investigate how much impurities derived from the bonding material and the like were contained when the recycled ingot was produced.

A test piece (100 mm × 200 mm × 15 mm) of the target material separated and cut by the same method as in Example 1 described above was obtained. The joint surface (first surface) of the target material was blasted at a speed of 500 mm ² / min. Regarding the type of abrasive used (similar to the abrasive used in Examples 1-3, 1-2 and 1-5) and the pressure of compressed air applied to the blast treatment (treatment pressure), The evaluation results are shown in Table 4 below. Other cleaning conditions were the same as in Example 1.
The joint surface of the target material obtained in Examples 3-1 to 3-4 is roughened, and the arithmetic average roughness Ra is measured by a contact type surface roughness meter (manufactured by Mitutoyo Co., Ltd., Surftest SJ). When each of the three points was measured by the method specified in JIS B 0601 (2001) using −301), the average values of Ra were 8.5 μm, 7.3 μm, 7.5 μm, and 7.1 μm, respectively. .. The arithmetic mean roughness Ra of the joint surface to which the joint material before the treatment was attached was 1.7 μm on average. Further, the normal reflectance in the entire wavelength range of 300 nm to 1500 nm of the joint surface of the target material was measured with an ultraviolet-visible near-infrared spectrophotometer (U-4100 type manufactured by Hitachi High-Technologies Corporation). A sample is irradiated with incident light having an incident angle of 5 ° using a 5 ° specular reflection accessory, and the reflectance of the reflected light reflected at the reflection angle of 5 ° with respect to the incident light is determined in increments of 100 nm of the incident light wavelength. It was. The maximum positive reflectance is when the wavelength of the incident light is 1300 nm, 0.4 to 0.5% for any target material, 0.3% when the wavelength is 500 nm, and 1000 nm. Was 0.2 to 0.3%. The maximum normal reflectance in the entire wavelength range of 300 nm to 1500 nm of the joint surface to which the bonding material before treatment is attached is about 2 to 3% when the wavelength of the incident light is 1300 nm, and 1 to 1 when the wavelength is 500 nm. When it was 2% and 1000 nm, it was 1 to 2%.
A part of the used target material after washing by the blasting treatment was collected, dissolved under vacuum (0.03 Torr) at 850 ° C., and stirred in the air to remove dross. Then, it was cooled in the air to produce a recycled ingot. The amount of impurities contained in the recycled ingot was subjected to a trace analysis of Sn, Zn, In, Cu and the like using GDMS (VG9000 manufactured by VG Elemental).

Types of Abrasives and Application of Blasting The analysis results of Examples 3-1 to 3-4 for each compressed air pressure are obtained from the unused target material as a reference example and the used target material (before cleaning). It is shown in Table 4 below together with the analysis results of the ingot produced by the same method (unit: mass ppm (wt ppm)).

As shown in Table 4, the total amount of impurities derived from the solder material (In, Sn, Zn) and the backing plate (Cu) contained in the recycled ingots produced in Examples 3-1 to 3-4. It was found that the amount was less than 4 ppm on a mass basis. In addition, the total amount of impurities was less than 10 ppm, and it was clarified that the risk of contamination by the abrasive was small. Further, although the flat plate type target material has been described in the above embodiment, the same treatment can be applied to a cylindrical target material to be joined to the backing tube by using a solder material (bonding material). You can get the result.

According to the method for cleaning the target material of the present invention, impurities derived from the bonding material and the supporting member forming the bonding layer can be easily and substantially completely removed from the target material used in the blasting treatment. Further, since the risk of contamination by the abrasive can be reduced, the method for cleaning the target material of the present invention is also suitable for final cleaning of the target material partially treated by another cleaning method such as chemical treatment.

1 Target material 2 Support member 3 Bonding layer 3a Solder layer 3b, 3b'Metallized layer 4 Nozzle head 10 Sputtering target 100 1st surface

Claims (11)

It is a method of cleaning the target material separated from the sputtering target formed by joining the target material and the support member with the joining material.
Injecting an abrasive having a new Mohs hardness of 3 or more and a bulk specific gravity of 2 g / cm ³ or less onto the first surface of the target material to which the target material and the support member are joined. including,
How to clean the target material. The method for cleaning a target material according to claim 1, wherein the value obtained by multiplying the new Mohs hardness of the abrasive and the particle size (μm) of the abrasive is 1100 or more and 6500 or less. The method for cleaning a target material according to claim 1 or 2, wherein the bulk specific gravity of the abrasive is 0.5 g / cm ³ or more and 1.7 g / cm ³ or less. The method for cleaning a target material according to any one of claims 1 to 3, wherein the new Mohs hardness of the abrasive is 12 or less. The method for cleaning a target material according to any one of claims 1 to 4, wherein the abrasive is an organic substance. The method for cleaning a target material according to any one of claims 1 to 5, wherein the abrasive is sprayed so as to form an angle of 30 ° or more and 60 ° or less with respect to the first surface. The method for cleaning a target material according to any one of claims 1 to 6, wherein the Vickers hardness of the target material is 100 or less. The method for cleaning a target material according to any one of claims 1 to 7, wherein the main component of the target material is aluminum. The method for cleaning a target material according to any one of claims 1 to 8, wherein the bonding material is a solder containing an alloy of tin, zinc, indium, lead or a metal thereof. A method for producing a target material, which comprises treating the target material by the method according to any one of claims 1 to 9. 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.

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