Method for recycling target material

Abstract

To provide a method for recycling a target material 1 joined to a backing plate 2 by a mechanical joining method.SOLUTION: A vertical surface is formed on the side surface of a target material 1 in a state where the side surface of a backing plate 2 is held by a vice 3. The backing plate 2 is mechanically removed in a state that the vertical surface is held by a vice 3, and after the backing plate 2 is removed, chemical treatment is performed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for recycling target materials, and more particularly to a method for recycling target materials joined to a backing plate by mechanical joining or welding. [Background technology]

[0002] The sputtering target is formed by bonding, for example, a target material made of high-purity aluminum and a backing plate made of a metal different from the target material.

[0003] The backing plate is bonded to the target to cool the target material when it is used for sputtering and to ensure the strength of the sputtering target. Bonding methods include brazing, diffusion bonding, welding, and mechanical bonding methods (e.g., cold isostatic pressing, pressing, rolling, etc.).

[0004] It should be noted that the target material is not completely consumed even when used in sputtering, and is therefore recovered and reused after use in sputtering.

[0005] Specifically, used sputtering targets are reused by separating the target material from the backing plate, removing foreign matter such as dust that may have been introduced from the surrounding environment during storage, transportation, handling, and separation, and removing the brazing material if one has been used. The clean target material is then melted and cast.

[0006] Recently, mainly from the viewpoint of cost, joining methods that do not use brazing materials have come to be used.

[0007] A bonding method that does not use brazing material is a "bonding method using diffusion bonding." Diffusion bonding involves bringing a target material and a backing plate into close contact with each other, and applying pressure to the extent that plastic deformation is minimized at temperatures below the melting points of both materials. This allows atoms to be transferred between the two materials through atomic diffusion, bonding the target material and the backing plate together (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 6716452 specification Summary of the Invention [Problem to be solved by the invention]

[0009] However, since a target material made of aluminum has a thin natural oxide film on its surface, atomic exchange tends to be insufficient.

[0010] Furthermore, as described in Patent Document 1, in the case of reuse, it is necessary to remove some of the target material from the bonding surface in order to eliminate foreign elements originating from the backing plate that have diffused near the bonding surface of the target material, which may result in a decrease in the yield of reuse.

[0011] The present invention has been made in view of the above points, and aims to provide a method for recycling a target material that has been joined to a backing plate by mechanical joining or welding. [Means for solving the problem]

[0012] In order to achieve the above-mentioned object, the target material recycling method of the present invention is a method for reusing a sputtering target having a target material mainly composed of aluminum and a backing plate mechanically joined to the back surface of the target material after using the target material for sputtering, and includes the steps of: forming a predetermined gripping region on the side of the target material; mechanically removing the backing plate from the sputtering target while holding the gripping region; and treating the target material with a chemical solution of at least one of an acid and a base after removing the backing plate.

[0013] Here, by forming a predetermined gripping area on the side of the target material, it becomes possible to grip the target material (more specifically, the gripping area of ​​the target material) using a predetermined jig (for example, a vise, etc.).

[0014] One example is when the side surface of the target material is mechanically processed to form a gripped region while the side surface of the backing plate is gripped.

[0015] Furthermore, the target material and the backing plate can be separated by mechanically removing the backing plate from the sputtering target while the gripping region is gripped.

[0016] Since the target material and backing plate are joined using a "mechanical joining method," there is no need to consider the influence of the diffusion layer as in diffusion bonding, and it is sufficient to remove the target material and backing plate until the joint surface is completely lost. That is, unlike sputtering targets bonded by "diffusion bonding," there is no need to remove excess material beyond the bonding surface, and there is no risk of a decrease in yield.

[0017] Furthermore, after removing the backing plate, the entire surface of the target material can be treated with at least one of an acid and a base chemical solution to remove foreign matter adhering to the surface of the target material (the "surface of the target material that is bonded to the backing plate," the "side surface opposite to the bonded surface," and the "side surface of the target material") and foreign matter that has entered the vicinity thereof. Furthermore, chemical treatment can also remove dust and the like from the target material. The target material may be masked with general-purpose masking tape or the like before being treated with the chemical solution.

[0018] Here, since used sputtering targets are treated as scrap, foreign matter in the environment may adhere to the target material, and foreign matter may enter the target material due to its own weight or external forces during transportation or handling. Furthermore, when the backing plate is separated (removed), there are other factors such as contact with chips from the backing plate and entry due to pressing. Therefore, by treating with a chemical solution, foreign matter can be removed from the target material, as described above.

[0019] When acid treatment is performed as the chemical treatment, foreign matter on the target material after the backing plate is separated (removed) is dissolved and removed. Furthermore, when base treatment is performed as the chemical treatment, foreign matter on the target material after the backing plate is separated (removed) is dissolved and removed, and the target material into which the foreign matter has entered is thinly dissolved, causing the foreign matter to separate from the target material.

[0020] An example of the chemical treatment here is treatment with 10% to 15% by weight of a base (e.g., sodium hydroxide) for 5 to 20 minutes, followed by treatment with 10% to 15% by weight of an acid (e.g., nitric acid) for 5 to 600 minutes.

[0021] Furthermore, the target material recycling method of the present invention is a method for reusing a sputtering target having a target material mainly composed of aluminum and a backing plate mechanically bonded to the back surface of the target material after the target material has been used for sputtering, and includes the steps of: mechanically removing a central region of the backing plate, which is a region of the backing plate that is bonded to the target material, while holding the backing plate from both the front and back surfaces, from a peripheral region of the backing plate that is not bonded to the target material; and treating the target material with at least one chemical solution of an acid or a base after removing the backing plate.

[0022] Here, the target material and the backing plate can be separated by mechanically removing the central region of the backing plate (the region bonded to the target material) while holding the backing plate from the front and back sides in the peripheral region of the backing plate (the region not bonded to the target material).

[0023] As the target material and the backing plate are joined by a "mechanical joining method," there is no need to consider the influence of a diffusion layer as in diffusion bonding, and as mentioned above, it is sufficient to remove the target material and the backing plate until the joint surface is completely lost.

[0024] As described above, after removing the backing plate, the entire surface of the target material can be treated with at least one of an acid and a base to remove foreign matter adhering to the surface of the target material (the "surface of the target material that is bonded to the backing plate," the "side surface opposite to the bonded surface," and the "side surface of the target material") and foreign matter that has entered the vicinity thereof. Furthermore, as described above, the chemical treatment can also remove dust and the like from the target material, and the chemical treatment may be performed in a masked state.

[0025] Furthermore, the target material recycling method of the present invention is a method for recycling a sputtering target having a target material mainly composed of aluminum and a backing plate joined to the back surface of the target material by mechanical bonding or joined to the outer edge of the target material by welding, for reusing the target material after using the target material for sputtering, and includes the steps of mechanically removing the backing plate from the sputtering target, and treating the target material with a chemical solution of at least one of an acid and a base after removing the backing plate.

[0026] The target material and the backing plate can then be separated by mechanically removing the backing plate from the sputtering target.

[0027] As mentioned above, when the target material and the backing plate are joined by a "mechanical joining method," there is no need to consider the influence of the diffusion layer as in the case of diffusion joining, and it is sufficient to remove the bonded surface between the target material and the backing plate until it is completely lost.

[0028] Furthermore, even when the target material and backing plate are joined by "welding," there is no need to consider the influence of the diffusion layer as in diffusion bonding, and it is sufficient to separate the welded portion (welded metal portion and heat-affected portion) so that no welded metal portion remains on the target material side. That is, even when the joining is performed by "welding," there is no need to remove excess material beyond the joining surface (which is necessary when joining by diffusion bonding), and there is no concern about a decrease in yield.

[0029] Here, examples of separation methods that do not leave any bonded surface on the target material side (when joined by a mechanical joining method) or separation that do not leave any weld metal portion on the target material side (when joined by welding) include cutting with a saw blade or cutting wheel, cutting with a blade, breaking with a press, grinding with a grinding wheel, and grinding with abrasive paper or abrasive cloth, or abrasive material made from abrasive paper or abrasive cloth (for example, a sanding disk or a flap disk).

[0030] An example of a sputtering target is one in which the backing plate has a backing plate body with a predetermined opening and an inner edge portion rising from the inner edge of the backing plate body, and the target material is joined by welding to the end of the inner edge portion on the opposite side from the backing plate body.A process for mechanically removing the backing plate from such a sputtering target is to mechanically remove the inner edge portion joined to the target material while holding the side of the backing plate.

[0031] As described above, after removing the backing plate, the entire surface of the target material can be treated with at least one of an acid and a base to remove foreign matter adhering to the surface of the target material (the "surface of the target material that is bonded to the backing plate," the "side surface opposite to the bonded surface," and the "side surface of the target material") and foreign matter that has entered the vicinity thereof. Furthermore, as described above, the chemical treatment can also remove dust and the like from the target material, and the chemical treatment may be performed in a masked state.

[0032] Furthermore, the target material recycling method of the present invention is a method for recycling a sputtering target having a target material mainly composed of aluminum and a backing plate mechanically bonded to the back surface of the target material or welded to the outer edge of the target material after the target material has been used for sputtering, and includes the steps of mechanically removing, from the sputtering target, a portion of the target material that is the portion bonded to the backing plate, and treating the remaining target material with a chemical solution of at least one of an acid and a base after the portion of the target material has been mechanically removed.

[0033] Here, the target material and the backing plate can be separated by mechanically removing a portion of the target material, which is the portion bonded to the backing plate, from the sputtering target.

[0034] As mentioned above, when the target material and the backing plate are joined by a "mechanical joining method," there is no need to consider the influence of the diffusion layer as in the case of diffusion joining, and it is sufficient to remove the bonded surface between the target material and the backing plate until it is completely lost.

[0035] Furthermore, even when the target material and backing plate are joined by "welding," there is no need to consider the influence of the diffusion layer as in diffusion bonding, and it is sufficient to separate the welded portion (welded metal portion and heat-affected portion) so that no welded metal portion remains on the target material side. That is, even when the joining is performed by "welding," there is no need to remove excess material beyond the joining surface (which is necessary when joining by diffusion bonding), and there is no concern about a decrease in yield.

[0036] Here, examples of separation methods that do not leave any bonded surface on the target material side (when joined by a mechanical joining method) or separation that do not leave any weld metal portion on the target material side (when joined by welding) include cutting with a saw blade or cutting wheel, cutting with a blade, breaking with a press, grinding with a grinding wheel, and grinding with abrasive paper or abrasive cloth, or abrasive material made from abrasive paper or abrasive cloth (for example, a sanding disk or a flap disk).

[0037] An example of a sputtering target is one in which the backing plate has a backing plate body with a predetermined opening and an inner edge portion rising from the inner edge of the backing plate body, and the target material is joined by welding to the end of the inner edge portion on the opposite side from the backing plate body.A process for mechanically removing a portion of the target material from such a sputtering target is to mechanically remove the target material joined to the inner edge portion while holding the side of the backing plate.

[0038] As described above, after removing a portion of the target material, the entire surface of the target material (remaining portion) can be treated with at least one of an acid and a base to remove foreign matter adhering to the surface of the target material (the "surface of the target material that is bonded to the backing plate," the "side surface opposite to the bonded surface," and the "side surface of the target material") and foreign matter that has entered the vicinity thereof. Furthermore, as described above, dust and the like on the target material can also be removed by chemical treatment, and the chemical treatment may be performed in a masked state. [Effects of the Invention]

[0039] The present invention makes it possible to recycle target materials that are joined to backing plates by mechanical joining or welding. [Brief explanation of the drawings]

[0040] [Figure 1] FIG. 1 is a schematic diagram for explaining a sputtering target. [Figure 2] FIG. 1 is a schematic diagram for explaining a first embodiment. [Figure 3] FIG. 10 is a schematic diagram for explaining a second embodiment. [Figure 4] FIG. 10 is a schematic diagram for explaining a third embodiment. [Figure 5] FIG. 10 is a schematic diagram for explaining a fourth embodiment. [Figure 6] FIG. 10 is a schematic diagram for explaining a fifth embodiment. [Figure 7] FIG. 10 is a schematic diagram for explaining a modified example. [Figure 8] FIG. 1 is a schematic diagram (1) for explaining a comparative example of a recycling method. [Figure 9] FIG. 2 is a schematic diagram (2) for explaining a comparative example of a recycling method. [Figure 10] FIG. 3 is a schematic diagram (3) for explaining a comparative example of a recycling method. [Figure 11] FIG. 1 is a schematic diagram (1) for explaining the measurement of substrate concentration. [Figure 12] Schematic diagram (2) for explaining the measurement of substrate concentration. DETAILED DESCRIPTION OF THE INVENTION

[0041] Hereinafter, a mode for carrying out the invention (hereinafter referred to as "embodiment") will be described. The explanation will be given in the following order. 1. First embodiment 2. Second embodiment 3. Third Embodiment 4. Fourth Embodiment 5. Fifth Embodiment 6. Variations

[0042] <1. First embodiment> [Configuration of sputtering target a] FIG. 1(a) is a schematic diagram illustrating an example of a sputtering target that is a target of the target material recycling method of the present invention.

[0043] A sputtering target a shown in FIG. 1(a) has a target material 1 and a backing plate 2, and the backing plate 2 is joined to the back surface of the target material 1 (the lower surface side in FIG. 1) by a mechanical joining method.

[0044] The target material 1 is made of an aluminum alloy with a purity of 99.9995 wt% (in this embodiment, 99.9995 wt% aluminum with 0.5% Cu added is used, and the impurity concentration is 0.0005 wt% or less), and is in the shape of a truncated cone with a height of 12 mm, and its back surface (the surface corresponding to the lower base of the truncated cone) is joined to the backing plate 2.

[0045] The backing plate 2 is made of super duralumin (JIS A2024) and has a circular flat plate shape (thickness: 13 mm) in plan view, and its surface is joined to the back surface of the target material 1 .

[0046] The mechanical joining methods used here include cold isostatic pressing, pressing, rolling, etc., and involve bringing the "back surface of the target material 1" and the "front surface of the backing plate 2" into contact and plastically deforming them to break the natural oxide film on the back surface (aluminum surface) of the target material 1, bringing the newly formed surfaces into contact with each other, and applying energy from an external force to the interface (contact surface) to join them.

[0047] In addition, in this embodiment, in order to increase the contact area and achieve a stronger bond (bonding by mechanical contact method), a method is adopted in which patterns are carved into the contact surfaces (the back surface of the target material 1 and the front surface of the backing plate 2) and contact and adhesion are achieved by plastic deformation.

[0048] In this embodiment, a pattern is engraved on both contact surfaces (the back surface of the target material 1 and the front surface of the backing plate 2), but a pattern may be engraved on only one of the contact surfaces (for example, only the front surface of the backing plate 2). Also, it is not necessary to engrave a pattern on the contact surface.

[0049] Furthermore, even if a pattern is engraved on the entire surface of the contact surface, it is not necessary for the pattern on the entire surface to interlock, and it is also possible for only a portion to interlock or to be in contact.

[0050] Furthermore, in this embodiment, the target material 1 is softened to facilitate plastic deformation, and joining is performed by a mechanical joining method in a low temperature range of 250°C or less (for example, room temperature), which is a temperature range that does not change the crystalline structure of the target material 1.

[0051] [Reuse of sputtering target a] Hereinafter, a method for recycling (reusing) the target material 1 after using the above-mentioned sputtering target a will be described. That is, an example of a method for recycling a target material to which the present invention is applied will be described.

[0052] In one example of a method for recycling a target material to which the present invention is applied, first, a used sputtering target a is held in a vice 3 as shown in FIG. 2(a). Specifically, with the target material 1 facing upward (the backing plate 2 facing downward), the side surface of the backing plate 2 is gripped using the vice 3.

[0053] When sputtering target a is used for sputtering, target material 1 is consumed. For this reason, sputtering target a shown in Fig. 2 shows depressions on the surface of target material 1 to indicate that target material 1 has been consumed (the same applies to Figs. 3 to 12).

[0054] Next, while the side of the backing plate 2 is being held, the side of the target material 1 (the area indicated by symbol A in Figure 2(a)) is cut (mechanically removed) with a blade, and the side of the target material 1 becomes a vertical surface (a surface that forms an angle of 90 degrees with the back surface of the target material 1), thereby forming a holding area as shown in Figure 2(b).

[0055] In this embodiment, the gripping area is described using a "vertical surface" as an example, but it is sufficient if the target material 1 can be gripped by a jig such as a vise, and it does not necessarily have to be a "vertical surface." Any area that can be stably gripped in relation to the jig such as a vise is sufficient.

[0056] Furthermore, in this embodiment, the side surface of the target material 1 is described as being "cut with a blade" as an example, but as long as a vertical surface (gripping area) can be formed, it is not necessarily limited to being "cut with a blade," and may also be "cutting with a saw blade or cutting wheel," "grinding with a grinding wheel," or "grinding with abrasive paper or abrasive cloth, or abrasive material made from abrasive paper or abrasive cloth." Furthermore, the gripping area may be formed by a method other than mechanical removal.

[0057] Next, the sputtering target a is turned over so that the backing plate 2 is on the upper side (the target material 1 is on the lower side), and as shown in Figure 2(c), the gripping area (the vertical surface formed on the side of the target material 1) is gripped with a vice 3 (at this time, the side of the backing plate 2 is not gripped by the vice), and the backing plate 2 is mechanically removed.

[0058] Specifically, while the target material 1 is held in a vise 3, it is cut from above (from the direction indicated by symbol B in Figure 2(c)) with a cutting tool until the joint surface with the target material 1 is completely lost, thereby separating the target material 1 (see Figure 2(d)).

[0059] Here, in this embodiment, the separation of the target material 1 is explained using the example of "cutting with a blade," but it does not necessarily have to be limited to "cutting with a blade," and it can also be "cutting with a saw blade or cutting wheel," "grinding with a grinding wheel," or "grinding with abrasive paper or abrasive cloth, or abrasive material made from abrasive paper or abrasive cloth."

[0060] Thereafter, as shown in FIG. 2(e), the target material 1 is degreased, subjected to a liquid treatment with 10% to 15% by weight sodium hydroxide for 5 to 20 minutes, and further subjected to a liquid treatment with 10% to 15% by weight nitric acid for 5 to 600 minutes, and then washed with water.

[0061] [effect] In one example of a method for recycling target material to which the present invention is applied, a gripping area (the vertical surface on the side of the target material 1) is formed, so that even if the target material 1 has been deformed due to use in sputtering, it can be stably gripped with a jig such as a vise, and the backing plate 2 can be mechanically removed.

[0062] Furthermore, the sputtering target a, which is the target of the target material recycling method to which the present invention is applied, is joined by a mechanical joining method, and therefore, when separating the backing plate 2, it is not necessary to consider the influence of the diffusion layer, and it is sufficient to remove the target material 1 and the backing plate 2 until the joint surface between them is completely lost. That is, unlike "bonding using diffusion bonding," there is no need to remove a certain amount of target material from the bonding surface, so there is no need to worry about a decrease in yield.

[0063] Furthermore, the sputtering target a that is the subject of the target material recycling method to which the present invention is applied is joined by a mechanical joining method, and there is no need to remove the brazing material (joining material) in regenerating the target material 1. Therefore, blasting treatment (for example, the treatment described in JP 2020-132997 A) is not required, and foreign matter can be removed by a short chemical treatment.

[0064] For example, in the case of joining using brazing material (jointing material), after blasting, liquid treatment with 10% to 15% by weight sodium hydroxide for 30 minutes or more, and further liquid treatment with 10% to 15% by weight nitric acid for 720 minutes or more, and then washing with water is required.

[0065] [Example 1] The first embodiment will be described below. In Example 1, verification is performed using a sputtering target a having an outermost diameter (diameter φ) of 540 mm. In Example 1, evaluation is also performed on "separation time" and "yield."

[0066] (About separation time) When separating the target material 1 from the backing plate 2, (1) Attach the jig to the equipment (2) Attach the workpiece to the jig (3) Mechanical removal (4) Remove the workpiece from the jig (5) Remove the jig from the equipment. It will go through a process such as: Here, the time required for steps (2) to (4) is measured as the "separation time."

[0067] In Example 1, steps (2) to (4) are repeated twice to form a gripping region prior to the process of separating the target material 1 and the backing plate 2. Therefore, the "separation time" is measured as the time it takes to repeat steps (2) to (4) twice.

[0068] In addition, the conditions for mechanical removal (cutting) in (3) are to select a feed rate that will prevent the workpiece from slipping off the jig.

[0069] (Regarding yield) First, two used sputtering targets a are prepared. Specifically, the same unused sputtering target a is used in sputtering under the same conditions to prepare two used sputtering targets a.

[0070] Next, one of the used sputtering targets a is cut into half (semicircular shape), and the target material 1 portion is measured with a vernier caliper and a three-dimensional measuring machine to calculate the volume of the target material 1. The calculated volume of the target material 1 is multiplied by the density of aluminum to calculate the weight of the target material 1.

[0071] The other used sputtering target a is recycled by the recycling method to which the present invention is applied, and the obtained target material is weighed to confirm the weight b.

[0072] Then, calculate the yield = (b / a) x 100.

[0073] Example 1 As Example 1, the recycling method (first embodiment) shown in FIGS. 2(a) to 2(e) was carried out. In the step of FIG. 2(e), the target material 1 was degreased, subjected to a liquid treatment with 15 wt % sodium hydroxide at 50°C for 5 minutes, and then further subjected to a liquid treatment with 15 wt % nitric acid at 25°C for 15 minutes, followed by rinsing with water.

[0074] (Comparative Example 1) In Comparative Example 1, as shown in FIG. 8, an attempt was made to invert a used sputtering target a and grip the side of the target material 1 with a vise 3 without forming a gripping area, but gripping was not possible, and the target material 1 and the backing plate 2 could not be separated.

[0075] (Comparative Example 2) As Comparative Example 2, first, as shown in FIG. 9(a), a used sputtering target a was pressed and held in an inverted state using a vacuum chuck 6. Specifically, the backing plate 2 was pressed and held by a vacuum chuck 6 in a state where the backing plate 2 was on the upper side (the target material 1 was on the lower side).

[0076] Next, while the backing plate 2 was held in pressure contact with the vacuum chuck 6, the backing plate 2 was mechanically removed. Specifically, the target material 1 was separated by cutting from above (the direction indicated by symbol B in Figure 9(a)) with a blade until the joint surface with the target material 1 was completely lost (see Figure 9(b)).

[0077] Thereafter, as shown in FIG. 9(c), a liquid treatment was carried out under the same conditions as in Example 1. Specifically, the target material 1 was degreased, subjected to a liquid treatment with 15 wt % sodium hydroxide at 50°C for 5 minutes, and then further subjected to a liquid treatment with 15 wt % nitric acid at 25°C for 15 minutes, and then washed with water.

[0078] (evaluation) Table 1 shows the "separation time" and "yield" for each of Example 1, Comparative Example 1, and Comparative Example 2.

[0079] [Table 1] JPEG2026001716000002.jpg17170

[0080] As is clear from Table 1, Example 1 (recycling method to which the present invention is applied) was found to enable separation in a shorter time than Comparative Example 2 (when a vacuum chuck was used).

[0081] <2. Second Embodiment> Hereinafter, a recycling (reuse) method for a used sputtering target a (see FIG. 1(a)) that is different from that in the first embodiment will be described. That is, another example of a method for recycling a target material to which the present invention is applied will be described.

[0082] In the second embodiment, the region of the backing plate 2 that is bonded to the target material 1 (the region indicated by the symbol X in FIG. 3(a)) is referred to as the "central region." Also, the region of the backing plate 2 that is not bonded to the target material 1 (the region indicated by the symbol Y in FIG. 3(a)) is referred to as the "peripheral region."

[0083] [Reuse of sputtering target a] In another example of a method for recycling a target material to which the present invention is applied, first, as shown in FIG. 3( a ), a used sputtering target a is turned upside down and held in a vice 3 . Specifically, with the backing plate 2 facing upward (the target material 1 facing downward), the peripheral region Y of the backing plate 2 is gripped from the front and back surfaces using the vice 3.

[0084] Next, the backing plate 2 is mechanically removed while being held from the front and back surfaces.

[0085] Specifically, with the backing plate 2 held by a vice 3 on both the front and back sides, the central region X of the backing plate 2 is cut from above (from the direction indicated by symbol B in FIG. 3(a)) with a cutting tool until the bonding surface with the target material 1 is completely lost, thereby separating the target material 1 (see FIG. 3(b)).

[0086] Here, in this embodiment, the separation of the target material 1 is explained using the example of "cutting with a blade," but this does not necessarily have to be limited to "cutting with a blade," and it may also be "cutting with a saw blade or cutting wheel," "grinding with a grinding wheel," or "grinding with abrasive paper or abrasive cloth, or an abrasive material made from abrasive paper or abrasive cloth."

[0087] Thereafter, as in the first embodiment, the target material 1 is degreased, subjected to a liquid treatment with 10% to 15% by weight of sodium hydroxide for 5 to 20 minutes, and further subjected to a liquid treatment with 10% to 15% by weight of nitric acid for 5 to 600 minutes, and then washed with water (see FIG. 3(c)).

[0088] [effect] In another example of a target material recycling method to which the present invention is applied, only the peripheral region Y of the backing plate 2 is gripped, and even while the backing plate 2 is still being gripped, the central region X of the backing plate 2 can be mechanically removed, thereby achieving separation of the target material 1 and the backing plate 2.

[0089] [Example 2] The second embodiment will be described below. In Example 2, verification is performed using a sputtering target a having an outermost diameter (diameter φ) of 540 mm. In Example 2, evaluations are also performed on "separation time," "yield," and "contamination value."

[0090] Here, the "separation time" is measured by measuring the time required for steps (2) to (4) shown in Example 1. In Example 2, steps (2) to (4) are not repeated twice. The "yield" is calculated in the same manner as in the first embodiment.

[0091] (Regarding pollution levels) The "substrate concentration" and "dissolution analysis value" described below are measured, and the Fe contamination value (= Fe dissolution analysis value - Fe substrate concentration) and Mg contamination value (= Mg dissolution analysis value - Mg substrate concentration) are calculated.

[0092] Here, the Fe contamination value is a value that indicates how much the Fe dissolution analysis value has increased from the Fe concentration in the base material, and is used to detect contamination from foreign matter in the environment and contamination from jigs during recycling.

[0093] Although there is more Si than Fe as a foreign substance in the environment, Si is contaminated from the crucible during melting and may be contained as an alloy element in the target material 1, so it is not suitable as an evaluation element.

[0094] The Mg contamination value is a value that indicates how much the Mg dissolution analysis value has increased from the base Mg concentration, and is used to detect contamination from the separated remains of the backing plate 2 and cutting chips during recycling (Mg is a component contained in the backing plate 2).

[0095] Although Cu is also contained in the backing plate 2 as a component, Cu is not suitable as an element to be evaluated because it may be contained in the target material 1 as an alloy element.

[0096] (Measurement of substrate density) An untreated used sputtering target a (see FIG. 11(a)) is cut into the target material 1 as shown in FIG. 11(b), thereby exposing the aluminum portion inside the target material 1.

[0097] The concentrations of iron (Fe) and magnesium (Mg) in the aluminum portion of the target material 1 thus exposed (portion indicated by symbol C in FIG. 11(b)) are measured by glow discharge mass spectrometry. The concentrations of iron and magnesium obtained by such measurements are referred to as the "base concentration of Fe" and the "base concentration of Mg."

[0098] (Dissolution analysis value) The target material 1 regenerated by the recycling method is dissolved, a solid sample is collected, and the concentrations of iron (Fe) and magnesium (Mg) in the solid sample are measured by glow discharge mass spectrometry. The concentrations of iron and magnesium obtained by such measurements are referred to as "Fe dissolution analysis value" and "Mg dissolution analysis value."

[0099] Example 2 As Example 2, the recycling method (second embodiment) shown in FIGS. 3(a) to 3(c) was carried out. In the step of FIG. 3(c), the target material 1 was degreased, subjected to a liquid treatment with 15 wt % sodium hydroxide at 50°C for 5 minutes, and then further subjected to a liquid treatment with 15 wt % nitric acid at 25°C for 15 minutes, and then washed with water.

[0100] In addition, in order to evaluate the liquid treatment, the test was also carried out in the cases of "no liquid treatment" and "long-term liquid treatment."

[0101] Here, the step in FIG. 3(c) was omitted as a "case without liquid treatment." In addition, as a case where the liquid treatment was extended for a longer period of time, in the process shown in Figure 3(c), the target material 1 was degreased, subjected to a liquid treatment with 15 wt% sodium hydroxide at 50°C for 30 minutes, and then further subjected to a liquid treatment with 15 wt% nitric acid at 25°C for 720 minutes, and then washed with water.

[0102] (evaluation) The "separation time" and "yield" for each of Example 2 and Comparative Example 2 are shown in Table 2-1.

[0103] [Table 2-1] JPEG2026001716000003.jpg17170

[0104] As is clear from Table 2-1, Example 2 (recycling method applying the present invention) had a similar yield to Comparative Example 2 (when a vacuum chuck was used), and it was found that separation could be performed in a short time.

[0105] Furthermore, as is clear from Table 2-1, it was found that Example 2 was better than Example 1 in both separation time and yield.

[0106] Furthermore, for Example 2, "Example 2 without liquid treatment," and "Example 2 with prolonged liquid treatment," the "level of Fe contamination" is shown in Table 2-2, and the "level of Mg contamination" is shown in Table 2-3.

[0107] [Table 2-2] JPEG2026001716000004.jpg22170

[0108] [Table 2-3] JPEG2026001716000005.jpg22170

[0109] As is clear from Table 2-2, Fe contamination was observed when no liquid treatment was performed, but the Fe contamination was eliminated by performing liquid treatment. That is, in Example 2 (recycling method to which the present invention is applied), it was found that Fe contamination could be sufficiently eliminated by ordinary liquid treatment, and that there was no need to perform liquid treatment for a long period of time.

[0110] Furthermore, as is clear from Table 2-3, no Mg contamination was observed even without liquid treatment.

[0111] <3. Third Embodiment> [Configuration of sputtering target b] FIG. 1(b) is a schematic diagram illustrating another example of a sputtering target that is a target of the target material recycling method of the present invention.

[0112] A sputtering target b shown in FIG. 1(b) has a target material 11 and a backing plate 12, and the backing plate 12 is joined to the edge of the target material 11 by welding.

[0113] The target material 11 is made of an aluminum alloy with a purity of 99.9995 wt% (in this embodiment, 99.9995 wt% aluminum with 0.5% Cu added is used, and the impurity concentration is 0.0005 wt% or less), and is shaped like a truncated cone with a height of 19 mm.The back surface of the target material (the surface corresponding to the lower base of the truncated cone) is joined to the backing plate 12.

[0114] The backing plate 12 is made of an aluminum alloy (JIS A6063) and is composed of a backing plate body 12a that is a flat, circular ring-shaped plate (thickness: 10 mm) when viewed from above, and an inner edge portion 12b (height: 20 mm) provided on the inner edge of the backing plate body 12a, and the inner edge portion 12b is joined to the target material 11.

[0115] [Reuse of sputtering target b] Hereinafter, a method for recycling (reusing) the target material 11 after using the above-mentioned sputtering target b will be described. That is, a further example of the method for recycling target materials to which the present invention is applied will be described.

[0116] In yet another example of a method for recycling a target material to which the present invention is applied, first, as shown in FIG. 4( a ), a used sputtering target b is turned upside down and held in a vice 3 . Specifically, with the backing plate 12 facing upward (the target material 11 facing downward), the side surface of the backing plate body 12a is gripped using the vice 3.

[0117] Next, while holding the backing plate 12 by its sides, the target material 11 is separated by cutting it from the inside (from the direction indicated by symbol B in Figure 4(a)) with a blade until the joint surface (welding surface) with the target material 11 is completely lost (see Figure 4(b)).

[0118] Here, in this embodiment, the separation of the target material 11 is explained using the example of "cutting with a blade," but this does not necessarily have to be limited to "cutting with a blade," and may also be "cutting with a saw blade or cutting wheel," "grinding with a grinding wheel," or "grinding with abrasive paper or abrasive cloth, or an abrasive material made from abrasive paper or abrasive cloth."

[0119] Thereafter, as in the first and second embodiments, the target material 11 is degreased, subjected to a liquid treatment with 10% to 15% by weight of sodium hydroxide for 5 to 20 minutes, and further subjected to a liquid treatment with 10% to 15% by weight of nitric acid for 5 to 600 minutes, and then washed with water (see FIG. 4(c)).

[0120] [effect] In yet another example of a target material recycling method to which the present invention is applied, the sputtering target b in question is configured such that the back surface of the target material 11 is bonded to the inner edge portion 12b (in other words, the entire back surface of the target material 11 is not bonded), and the bonded surface (welded surface) can be mechanically removed even while the backing plate 12 is still being held, thereby realizing separation of the target material 11 and the backing plate 12.

[0121] Furthermore, the sputtering target b, which is the target of the target material recycling method to which the present invention is applied, is joined by welding, and there is no need to consider the influence of the diffusion layer when separating the backing plate 12. It is sufficient to remove the welded portion (welded metal portion and heat-affected portion) on the target material 11 side until the welded metal portion is completely lost. That is, unlike "bonding using diffusion bonding," there is no need to remove a certain amount of target material from the bonding surface, so there is no need to worry about a decrease in yield.

[0122] Furthermore, the sputtering target b, which is the subject of the target material recycling method to which the present invention is applied, is joined by welding, and there is no need to remove the brazing material (joining material) when regenerating the target material 11. Therefore, blasting treatment (for example, the treatment described in Patent Publication No. 2020-132997) is not required, and foreign matter can be removed by a short chemical treatment.

[0123] [Example 3] The third embodiment will be described below. In Example 3, verification is performed using a sputtering target b having an outermost diameter (diameter φ) of 320 mm. In Example 3, evaluation is also performed on "separation time" and "yield."

[0124] Here, the "separation time" is measured by measuring the time required for steps (2) to (4) shown in Example 1. In Example 3, steps (2) to (4) are not repeated twice. The "yield" is calculated in the same manner as in the first embodiment.

[0125] Example 3 As Example 3, the recycling method (third embodiment) shown in FIGS. 4(a) to 4(c) was carried out. In the step of FIG. 4(c), the target material 11 was degreased, subjected to a liquid treatment with 15 wt % sodium hydroxide at 50°C for 5 minutes, and then further subjected to a liquid treatment with 15 wt % nitric acid at 25°C for 15 minutes, and then washed with water.

[0126] (Comparative Example 3) As Comparative Example 3, first, as shown in FIG. 10(a), a used sputtering target b was pressed and held in an inverted state using a vacuum chuck 6. Specifically, the backing plate 12 was held by pressure using a vacuum chuck 6 with the backing plate 12 facing upward (the target material 11 facing downward).

[0127] Next, while the backing plate 12 was held in pressure contact with the vacuum chuck 6, it was mechanically removed. Specifically, the target material 11 was separated by cutting from above (the direction indicated by symbol B in Figure 10(a)) with a blade until the joint surface with the target material 11 was completely lost (see Figure 10(b)).

[0128] Thereafter, as shown in FIG. 10(c), a liquid treatment was carried out under the same conditions as in Example 3. Specifically, the target material 11 was degreased, subjected to a liquid treatment with 15 wt % sodium hydroxide at 50°C for 5 minutes, and then further subjected to a liquid treatment with 15 wt % nitric acid at 25°C for 15 minutes, and then washed with water.

[0129] (evaluation) The "separation time" and "yield" for each of Example 3 and Comparative Example 3 are shown in Table 3.

[0130] [Table 3] JPEG2026001716000006.jpg17170

[0131] As is clear from Table 3, Example 3 (recycling method applying the present invention) had a similar yield to Comparative Example 3 (when a vacuum chuck was used), and it was found that separation was possible in a short time.

[0132] <4. Fourth embodiment> Hereinafter, a recycling (reuse) method for the used sputtering target b (see FIG. 1(b)) that is different from that in the third embodiment will be described. That is, still another example of the method for recycling target materials to which the present invention is applied will be described.

[0133] In still another example of a method for recycling a target material to which the present invention is applied, first, as shown in FIG. 5(a), a used sputtering target b is turned upside down and placed on a ring-shaped die 4. Specifically, with the backing plate 12 facing up (the target material 11 facing down), the front surface of the target material 11 (the surface opposite to the back surface bonded to the inner edge portion 12b) is placed on the die 4.

[0134] Next, with the sputtering target b placed on the die 4, the die 4 is punched from above with a press 5 to separate the target material.

[0135] Thereafter, as in the first, second, and third embodiments, the target material 11 is degreased, subjected to a liquid treatment with 10% by weight to 15% by weight sodium hydroxide for 5 to 20 minutes, and further subjected to a liquid treatment with 10% by weight to 15% by weight nitric acid for 5 to 600 minutes, and then washed with water (see FIG. 5(b)).

[0136] [effect] In yet another example of a target material recycling method to which the present invention is applied, the sputtering target b to be processed is configured such that the back surface of the target material 11 is bonded to the inner edge portion 12b (in other words, the entire back surface of the target material 11 is not bonded), and it can be placed on a ring-shaped die and punched out with a press, thereby realizing separation of the target material 11 and the backing plate 12.

[0137] [Example 4] The fourth embodiment will be described below. In Example 4, verification is performed using a sputtering target b having an outermost diameter (diameter φ) of 320 mm. In Example 4, evaluation is also performed on "separation time" and "yield."

[0138] Here, the "separation time" is measured by measuring the time required for steps (2) to (4) shown in Example 1. In Example 4, steps (2) to (4) are not repeated twice. The "yield" was calculated in the same manner as in Example 1.

[0139] Example 4 As Example 4, the recycling method (fourth embodiment) shown in Figs. 5(a) and 5(b) was carried out. In the step of FIG. 5(b), the target material 11 was degreased, subjected to a liquid treatment with 15 wt % sodium hydroxide at 50°C for 5 minutes, and then further subjected to a liquid treatment with 15 wt % nitric acid at 25°C for 15 minutes, and then washed with water.

[0140] (evaluation) Table 4 shows the "separation time" and "yield" for each of Example 4 and Comparative Example 3.

[0141] [Table 4] JPEG2026001716000007.jpg18170

[0142] As is clear from Table 4, Example 4 (recycling method to which the present invention is applied) was found to enable separation in an extremely short time compared to Comparative Example 3 (when a vacuum chuck was used).

[0143] Furthermore, as is clear from Table 4, Example 4 was found to have an extremely good separation time compared to Examples 1 to 3.

[0144] <5. Fifth Embodiment> Hereinafter, a recycling (reuse) method for a used sputtering target b (see FIG. 1(b)) that is different from the third and fourth embodiments will be described. That is, still another example of the method for recycling target materials to which the present invention is applied will be described.

[0145] In still another example of a method for recycling a target material to which the present invention is applied, first, a used sputtering target b is held in a vice 3 as shown in FIG. 6(a). Specifically, with the target material 11 facing upward (the backing plate 12 facing downward), the side surface of the backing plate body 12a is gripped using the vice 3.

[0146] Next, while holding the backing plate 12 by its sides, the target material 11 is separated by cutting it from above (from the direction indicated by symbol B in FIG. 6(a)) with a blade until the joint surface (welded surface) with the backing plate 12 is completely lost (see FIG. 6(b)).

[0147] Here, in this embodiment, the separation of the target material 11 is explained using the example of "cutting with a blade," but this does not necessarily have to be limited to "cutting with a blade," and may also be "cutting with a saw blade or cutting wheel," "grinding with a grinding wheel," or "grinding with abrasive paper or abrasive cloth, or an abrasive material made from abrasive paper or abrasive cloth."

[0148] Thereafter, as in the first, second, third, and fourth embodiments, the target material 11 is degreased, subjected to a liquid treatment with 10% by weight to 15% by weight sodium hydroxide for 5 to 20 minutes, and further subjected to a liquid treatment with 10% by weight to 15% by weight nitric acid for 5 to 600 minutes, and then washed with water (see FIG. 6(c)).

[0149] [effect] In yet another example of a target material recycling method to which the present invention is applied, the sputtering target b in question is configured such that the back surface of the target material 11 is bonded to the inner edge portion 12b (in other words, the entire back surface of the target material 11 is not bonded), and even while the backing plate 12 is still being held, the weld metal portion of the welded portion (welded metal portion and heat-affected portion) can be mechanically removed, thereby realizing separation of the target material 11 and the backing plate 12.

[0150] Furthermore, the sputtering target b, which is the subject of the target material recycling method to which the present invention is applied, is joined by welding, and there is no need to remove the brazing material (joining material) when regenerating the target material 11. Therefore, blasting treatment (for example, the treatment described in Patent Publication No. 2020-132997) is not required, and foreign matter can be removed by a short chemical treatment.

[0151] [Example 5] The fifth embodiment will be described below. In Example 5, verification is performed using a sputtering target b having an outermost diameter (diameter φ) of 320 mm. In Example 5, evaluations are also performed on "separation time," "yield," and "contamination value."

[0152] Here, the "separation time" is measured by measuring the time required for steps (2) to (4) shown in Example 1. In Example 5, steps (2) to (4) are not repeated twice. The "yield" is calculated in the same manner as in the first embodiment.

[0153] Furthermore, the "substrate concentration" for calculating the "contamination value" is determined as follows. That is, the target material 11 of an untreated sputtering target b (see FIG. 12(a)) is cut as shown in FIG. 12(b) to expose the aluminum portion inside the target material 11.

[0154] The concentrations of iron (Fe) and magnesium (Mg) in the aluminum portion of the target material 11 thus exposed (portion indicated by symbol C in FIG. 12(b)) are measured by glow discharge mass spectrometry. The concentrations of iron and magnesium obtained by such measurements are referred to as the "base concentration of Fe" and the "base concentration of Mg."

[0155] Example 5 As Example 5, the recycling method (fifth embodiment) shown in FIGS. 6(a) to 6(c) was carried out. In the step of FIG. 6(c), the target material 11 was degreased, subjected to a liquid treatment with 15 wt % sodium hydroxide at 50°C for 5 minutes, and then further subjected to a liquid treatment with 15 wt % nitric acid at 25°C for 15 minutes, and then washed with water.

[0156] In addition, in order to evaluate the liquid treatment, the test was also carried out in the cases of "no liquid treatment" and "long-term liquid treatment."

[0157] Here, the step in FIG. 6(c) was omitted as a "case without liquid treatment." In addition, as a case where the liquid treatment was extended for a long period of time, in the process of Figure 6(c), the target material 11 was degreased, subjected to a liquid treatment with 15 wt% sodium hydroxide at 50°C for 30 minutes, and then further subjected to a liquid treatment with 15 wt% nitric acid at 25°C for 720 minutes, and then washed with water.

[0158] (evaluation) The "separation time" and "yield" for each of Example 5 and Comparative Example 3 are shown in Table 5-1.

[0159] [Table 5-1] JPEG2026001716000008.jpg17170

[0160] As is clear from Table 5-1, Example 5 (recycling method to which the present invention is applied) was found to enable separation in an extremely short time compared to Comparative Example 3 (when a vacuum chuck was used).

[0161] Furthermore, as is clear from Table 5-1, Example 5 was found to have an extremely good separation time compared to Examples 1 to 3.

[0162] Furthermore, for Example 5, "Example 5 without liquid treatment," and "Example 5 with prolonged liquid treatment," the "level of Fe contamination" is shown in Table 5-2, and the "level of Mg contamination" is shown in Table 5-3.

[0163] [Table 5-2] JPEG2026001716000009.jpg23170

[0164] [Table 5-3] JPEG2026001716000010.jpg23170

[0165] As is clear from Table 5-2, Fe contamination was observed when no liquid treatment was performed, but the Fe contamination was eliminated by performing liquid treatment. That is, in Example 5 (recycling method to which the present invention is applied), it was found that Fe contamination could be sufficiently eliminated by ordinary liquid treatment, and that there was no need to perform liquid treatment for a long period of time.

[0166] Furthermore, as is clear from Table 5-3, no Mg contamination was observed even without liquid treatment.

[0167] <6. Variations> In the above-described first embodiment (see FIG. 2), second embodiment (see FIG. 3), and third embodiment (see FIG. 4), the explanation is given taking as an example a case where the sputtering target is inverted and gripped, and the backing plate is removed from above or from the inside. However, it is sufficient if the backing plate can be removed, and it is not necessary to invert and hold the sputtering target. The backing plate may be removed from below (first embodiment, second embodiment) or from the inside (third embodiment) after holding the sputtering target without inverting it.

[0168] In the fourth embodiment (see FIG. 5) described above, the case where the sputtering target is placed upside down has been described as an example. However, it is sufficient to be able to remove the backing plate, and it is not necessary to place the sputtering target in an inverted state. As shown in Figure 7, the back surface of the target material 11 (the surface with the outer edge portion 11b) may be placed on the die 4 with the target material 11 facing up (the backing plate 12 facing down).

[0169] Furthermore, in the above-mentioned fifth embodiment (see FIG. 6), an example has been described in which the sputtering target is gripped without being turned over, and the target material is removed from above. However, it is sufficient to be able to remove the target material, and it is not necessary to hold the sputtering target without inverting it; the sputtering target may be inverted and held, and then the target material may be removed from below.

[0170] In addition, in the above-mentioned first embodiment (see Figure 2), second embodiment (see Figure 3), third embodiment (see Figure 4), and fifth embodiment (see Figure 6), the example is given in which the target material 1 and the backing plate 2 are held so as to be aligned vertically. However, it is sufficient to be able to grip the sputtering target a and remove the backing plate, and it is not necessary to grip them so that they are aligned vertically; the target material 1 and backing plate 2 may be gripped so that they are aligned horizontally. In this case, processing is performed using a horizontal lathe or the like. [Explanation of symbols]

[0171] 1. Target material 2 Backing Plates 3 Vice 4 dice 5 Press 6 Vacuum Chuck 11 Target material 12 Backing Plate

Claims

1. A method for recycling a sputtering target having a target material mainly made of aluminum and a backing plate mechanically joined to a back surface of the target material, for reusing the target material after the target material has been used for sputtering, comprising: forming a predetermined gripping area on a side surface of the target material; mechanically removing the backing plate from the sputtering target while gripping the gripping region; and after removing the backing plate, subjecting the target material to a chemical treatment using at least one of an acid and a base. How to recycle target materials.

2. While gripping the side surface of the backing plate, The side surface of the target material is mechanically processed to form the gripping area. The method for recycling a target material according to claim 1 .

3. A method for recycling a sputtering target having a target material mainly made of aluminum and a backing plate mechanically joined to a back surface of the target material, for reusing the target material after the target material has been used for sputtering, comprising: a step of mechanically removing a central region of the backing plate that is a region bonded to the target material while holding the backing plate from the front and back surfaces in a peripheral region of the backing plate that is a region not bonded to the target material; and after removing the backing plate, subjecting the target material to a chemical treatment using at least one of an acid and a base. How to recycle target materials.

4. A method for recycling a sputtering target having a target material mainly made of aluminum and a backing plate joined to the back surface of the target material by mechanical joining or joined to the outer edge of the target material by welding, after the target material has been used for sputtering, comprising: mechanically removing the backing plate from the sputtering target; and after removing the backing plate, subjecting the target material to a chemical treatment using at least one of an acid and a base. How to recycle target materials.

5. the backing plate is joined to the target material by welding; The step of mechanically removing the backing plate comprises: The backing plate is cut with a saw blade or cutting wheel, or cut with a blade, or broken by a press, or ground with a grinding wheel, or ground with abrasive paper, abrasive cloth, or an abrasive material made from abrasive paper or abrasive cloth, so that no weld metal portion remains on the target material side. The method for recycling a target material according to claim 4.

6. The backing plate has a backing plate body provided with a predetermined opening and an inner edge portion rising from an inner edge of the backing plate body, the target material is joined by welding to an end of the inner edge portion opposite the backing plate body, The step of mechanically removing the backing plate from the sputtering target comprises: While holding the side of the backing plate, the inner edge portion bonded to the target material is mechanically removed. The method for recycling a target material according to claim 4 or 5.

7. A method for recycling a sputtering target having a target material mainly made of aluminum and a backing plate joined to the back surface of the target material by mechanical joining or joined to the outer edge of the target material by welding, after the target material has been used for sputtering, comprising: mechanically removing a portion of the target material bonded to the backing plate from the sputtering target; and after mechanically removing a portion of the target material, treating the remaining target material with at least one of an acid and a base. How to recycle target materials.

8. the backing plate is joined to the target material by welding; The step of mechanically removing a portion of the target material includes: The target material is cut with a saw blade or cutting wheel, or cut with a blade, or broken by a press, or ground with a grinding wheel, or ground with abrasive paper, abrasive cloth, or an abrasive material made from abrasive paper or abrasive cloth, so that no weld metal portion remains on the remaining target material side. The method for recycling a target material according to claim 7.

9. The backing plate has a backing plate body provided with a predetermined opening and an inner edge portion rising from an inner edge of the backing plate body, the target material is joined by welding to an end of the inner edge portion opposite the backing plate body, The step of mechanically removing a portion of the target material includes: While holding the side surface of the backing plate, the target material bonded to the inner edge portion is mechanically removed. The method for recycling a target material according to claim 7 or 8.

10. The chemical treatment is Treatment with 10% to 15% by weight of base for 5 to 20 minutes, followed by treatment with 10% to 15% by weight of acid for 5 to 600 minutes.

9. A method for recycling a target material according to claim 1, 2, 3, 4, 5, 7 or 8.

Images