TWI771394B - Method for cleaning target, method for producing target, method for producing regenerated ingot, and regenerated ingot - Google Patents

Abstract

A method of cleaning a target material, comprising: separating the target material from a sputtering target formed by combining a target material mainly containing metal and a support member by a bonding material; The step of processing the joint surface of the support member.

Description

Method for cleaning target, method for producing target, and regenerated ingot Manufacturing method and recycled ingot

The present invention relates to a method for recovering and cleaning a target, a method for producing a target, a method for producing a regenerated ingot, and a regenerated ingot.

The sputtering target is generally formed by bonding (bonding) a target including a metal, an alloy, or a ceramic to a support member by a bonding material. The target material is recovered after its use, and the metal is melted and cast again, whereby it can be reused (regenerated) as an ingot (slab, ingot).

Regarding the reuse of the target, for example, in Japanese Patent Laid-Open No. 2005-23350, Japanese Patent Laid-Open No. 2005-23349, or International Publication No. 2015/151498, it is disclosed that the surface of the sputtering target is adhered by acid. material removal.

As a result of diligent studies, the present inventors found that the target is separated from the sputtering target in which the target and the support member are bonded by a bonding material, and the bonding surface of the target and the support member is treated with an alkali, Thereby, impurities such as the bonding material adhering to the target material can be peeled off and removed from the target material, and the present invention has been completed.

This application is related to the following inventions.

[1]

A method for cleaning a target, comprising cleaning the target of a sputtering target that is formed by combining a target mainly containing metal and a support member by a bonding material and used in sputtering, the cleaning target The method of the invention comprises: the step of separating the target material from the sputtering target; and the step of treating the bonding surface with the support member in the target material obtained from the step with an alkali.

[2]

The method according to the above [1], which includes the step of further treating the bonding surface with the support member in the target material with an acid after the step of treating with an alkali.

[3]

The method according to [1] or [2], wherein the metal is aluminum.

[4]

A method for producing a target, comprising the step of cleaning the target by the method according to any one of the above [1] to [3].

[5]

A method for producing a regenerated ingot, which includes the step of casting a target cleaned by the method described in [1] to [3].

[6]

A regenerated ingot derived from a target material of a sputtering target obtained by bonding a target material mainly containing metal and a support member by a bonding material, wherein the regenerated ingot contains aluminum as a main component, and is derived from the bonding The total amount of the elements of the material and the support member is less than 10 ppm on a weight basis.

1: target

2: support member

3: Bonding material (or bonding layer)

4: Solder layer

5, 5': metallization layer

10, 20, 30: Sputtering target

FIG. 1 is a schematic diagram schematically showing an example of the treatment of the target according to the present invention and the regeneration of the target using the same.

FIG. 2 is a schematic view showing the coupling of the target material of the sputtering target and the support member.

FIG. 3 is a schematic view showing the coupling of a target material and a support member of another sputtering target.

FIG. 4 is a schematic view showing the coupling of a target material and a support member of another sputtering target.

In the present invention, the "sputtering target" is formed by bonding a target mainly containing a metal (element) and a support member with a bonding material, and is not particularly limited as long as it can be used in sputtering. When the sputtering target is a flat plate type, a flat plate-shaped backing plate can be used as the support member. In addition, when the sputtering target is cylindrical, a cylindrical backing tube can be used as the support member. Here, a cylindrical support tube can be inserted into the cylindrical target, and the inner peripheral portion of the cylindrical target and the outer peripheral portion of the support tube can be joined by a bonding material.

The "target" can mainly contain a metal (element), for example, a material selected from aluminum (Al), copper (Cu), chromium (Cr), iron (Fe), tantalum (Ta), titanium (Ti), zirconium (Zr) , Tungsten (W), Molybdenum (Mo), Niobium (Nb), Silver (Ag), Cobalt (Co), Ruthenium (Ru), Platinum (Pt), Palladium (Pd), Gold (Au), Rhodium (Rh) The metal (element) in the group consisting of iridium (Ir) and nickel (Ni) may also be an alloy containing the metal, and as the main component, preferably aluminum (purity 99.99% (4N) Above, preferably 99.999% pure (5N) or higher) or copper (99.99% pure (4N) or higher). target The size, shape and structure of the material are not particularly limited. As the target, it is preferable to use a plate-shaped target.

When the support member is a "support plate", it mainly contains copper (Cu), chromium (Cr), aluminum (Al), titanium (Ti), tungsten (W), molybdenum (Mo), and tantalum (Ta) The metals (elements) in the group consisting of , niobium (Nb), iron (Fe), cobalt (Co), and nickel (Ni) may also be alloys containing the metals. As a support member, in the case of a "support plate", among them, copper (oxygen-free copper), a chromium copper alloy, an aluminum alloy, etc. are preferable. The size, shape, and structure of the support plate are not particularly limited as long as it is a plate-shaped one on which the target can be arranged.

In the case where the support member is a "support pipe", the metal to be formed is also the same as in the case of the above-mentioned support plate. As a support member, in the case of a "support pipe", among them, stainless steel (SUS), titanium, a titanium alloy, etc. are preferable. The size of the support tube is generally longer than that of the cylindrical target in order to be inserted into the cylindrical target and joined, and the outer diameter of the support tube is preferably slightly smaller than the inner diameter of the cylindrical target. .

The "bonding material" is not particularly limited as long as it contributes to the bonding of the target material and the support member and can be used to form a sputtering target ( FIG. 2 ). The joining materials include welding materials, brazing materials, and the like.

The so-called "solder material" is a material containing a metal or alloy with a low melting point (for example, 723K or less), for example, a material containing a material selected from the group consisting of indium (In), tin (Sn), zinc (Zn), lead (Pb), silver ( Materials of metals or their alloys in the group consisting of Ag), copper (Cu), bismuth (Bi), cadmium (Cd) and antimony (Sb). More specifically, In, In-Sn, Sn-Zn, Sn-Zn-In, In-Ag, Sn-Pb-Ag, Sn-Bi, Sn-Ag-Cu, Pb-Sn, Pb-Ag, Zn-Cd, Pb-Sn-Sb, Pb-Sn-Cd, Pb-Sn-In, Bi-Sn-Sb, etc.

As the "brazing material", the target material and the support member can be bonded together, and as long as it is a metal or alloy having a lower melting point than the target material and the support member, it can be used without particular limitation.

As the joining material, it is preferable to use a welding material such as In or In alloy, Sn or Sn alloy, which generally has a low melting point.

For example, a metal (element) and a diffusion layer (alloy layer) contained in the target material can be formed on the bonding surface of the solder material and the target material by heating and bonded. A metal (element) and a diffusion layer (alloy layer) contained in the support member may be similarly formed and bonded to the welding material on the bonding surface with the support member. A solder layer can be formed from such a solder material, and the target material and support member can be joined (Fig. 3).

Generally speaking, if only the welding material is placed on the target material or the support member, an oxide film existing on the surface of the target material or the support member may be affected, and sufficient bonding strength may not be obtained. Therefore, in order to improve the wettability of the solder to these surfaces, a metalized layer can be provided.

The term "metallization" refers to a treatment method that can generally be used to form a metal film on a non-metallic surface, and in the present invention, means that when a target or a support member has an oxide film, etc., a metallization method is used. The welding material is combined with the target material or the support member to form a metallized layer. The metallization layer can be formed, for example, by using an ultrasonic soldering iron to destroy the oxide film of the target or the support member by the vibration energy of the ultrasonic wave (cavitation effect), and heating the oxide film with the oxide film in the oxide film. Oxygen atoms together with metal atoms contained in the welding material for metallization and metal atoms contained in the target material or support member The metal atoms in the chemical bond. The bonding material can be used for the formation of the metallization layer.

The metallization layers (5, 5') (see Fig. 4) that can be formed in this way can also be joined to the solder layer (4), and can be located between the target (1) and the solder layer (4), Between the support member (2) and the welding layer (4), the target material (1) and the welding layer (4) and the support member (2) and the welding layer (4) are firmly bonded together.

The thickness of the solder layer is, for example, in the range of 10 μm to 1000 μm, preferably 50 μm to 500 μm in the case of the flat plate type, and in the range of, for example, 100 μm to 2000 μm, preferably 250 μm to 1500 μm in the case of the cylindrical type.

The thickness of the metallized layer is, for example, in the range of 1 μm to 100 μm, preferably 10 μm to 100 μm, and more preferably 5 μm to 50 μm, for both the flat plate type and the cylindrical type.

Solder materials that can be used for metallization are those containing materials selected from the group consisting of indium (In), tin (Sn), zinc (Zn), lead (Pb), silver (Ag), copper (Cu), bismuth (Bi), cadmium (Cd) and antimony (Sb) in the group consisting of metal or alloy materials, etc., more specifically, In, In-Sn, Sn-Zn, Sn-Zn-In, In-Ag, Sn-Pb -Ag, Sn-Bi, Sn-Ag-Cu, Pb-Sn, Pb-Ag, Zn-Cd, Pb-Sn-Sb, Pb-Sn-Cd, Pb-Sn-In, Bi-Sn-Sb, etc. What is necessary is just to select suitably the material with high affinity with a target material or a support member.

In the present invention, for example, after the sputtering target is used in sputtering, the target is separated (peeled) from the sputtering target. The method of separating the target from the support member is not particularly limited. For example, the bonding layer (or bonding layer) that can be formed from the bonding material may be heated (for example, 180° C. to 300° C.) to soften or melt the bonding layer, and the bonding layer may be physically destroyed if necessary, and the target The material is separated from the supporting member.

In the case where the target is a flat plate type, the surface on the side of the separated target that is bonded (or bonded) to the support member (hereinafter, may also be referred to as "bonding face" or "bonding face") At least a part of the bonding material is adhered to and remains thereon. Even if the bonding material attached to the separated bonding surface is scraped off with a spatula (for example, a spatula made of silicone), it is difficult to completely remove the attached bonding material, especially the bonding material with the target cannot be removed. metallization layer. Usually, a metallization layer with a thickness of several μm to 100 μm and a solder layer with a thickness of about 50 μm to 200 μm remain. The bonding material may adhere and remain on the sputtering surface of the target. The reason for this is, for example, that the molten bonding material adheres to the sputtering surface when the target is separated. As other reasons, in order to overlap and store the targets, the bonding surface and the sputtering surface are brought into contact, and the bonding material of the bonding surface is attached to the sputtering surface. The treatment with alkali can also be applied to the sputtered surface.

In the case where the target is cylindrical, the cylindrical target can be joined to the outer peripheral portion of the cylindrical support tube by the bonding material, so as in the case of the plate-shaped target, after the separation A bonding material was attached to the bonding surface (inner peripheral part) of the target material, and the bonding material was not completely removed due to the inclusion of a metallized layer. The bonding material may adhere and remain on the sputtering surface of the target. Furthermore, the components derived from the support tube may also be mixed as impurities. Therefore, in a cylindrical target material, this cleaning method can also be applied to the outer peripheral part or the inner peripheral part which is a sputtering surface.

The presence of adhesion of the bonding material in the separated target material can be confirmed by, for example, Energy Dispersive X-ray Fluorescence Analysis (EDXRF: Energy Dispersive X-ray Fluorescence Analysis). There is also a metal element self-supporting member to the target The diffusion of the material (especially in the vicinity of the joint surface) can also be confirmed by EDXRF in the same manner about such a metal element. In addition, even wavelength dispersive X-ray fluorescence analysis (WDXRF: Wavelength Dispersive X-ray Fluorescence Analysis), Electron Probe Micro Analysis (EPMA: Electron Probe Micro Analysis), Auger Electron Spectroscopy (AES: Auger Electron Spectroscopy), X-ray Photoelectron Spectroscopy (XPS: X-ray Photoelectron Spectroscopy), Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS: Time-of-Flight Secondary Ion Mass Spectrometry), Laser Irradiation Type Inductively Coupled Electron Spectroscopy Plasma mass spectrometry (LA-ICP-MS: Laser Ablation Inductively Coupled Plasma Mass Spectrometry), X-ray Diffraction (XRD: X-ray Diffraction Analysis) and other analytical methods can also confirm impurities originating from bonding materials and support members, However, confirmation by EDXRF and WDXRF is preferable in terms of the simplicity of analysis and the wideness of the analysis range.

When an ingot (hereinafter, also sometimes referred to as a "slab" or "ingot") is produced directly using the separated target to which the bonding material is attached, and the target is remanufactured from the ingot, the resulting The components of the bonding material are mixed with impurities. Furthermore, there is a case where the metal element diffuses from the supporting member to the target and is mixed in as an impurity. There are also cases where such a metal element is mixed into the ingot as an impurity.

In the present invention, after the target is separated from the sputtering target, at least the bonding surface where the bonding material is attached to the target and where the bonding material remains is treated with an alkali, thereby cleaning. By performing this treatment, the alkali corrodes the target material, so that the bonding material can be peeled off and removed from the target material, and impurities derived from the support member can be easily removed ( FIG. 1 ).

(Method for cleaning used targets)

. Alkali treatment

In the present invention, the bonding surface with the support plate in the target material separated from the sputtering target is treated with an alkali.

Examples of the base that can be used in the present invention include hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; hydroxides of alkaline earth metals such as calcium hydroxide, strontium hydroxide, and barium hydroxide. ; Sodium carbonate, sodium phosphate, ammonia, guanidine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, etc. If necessary, two or more kinds of bases may be used in combination.

In addition to the above-mentioned base, a chelating agent that complexes with the ions of the metal constituting the target may be added. As a chelating agent, when a target material is aluminum, hepto gluconic acid (Hepto gluconic acid), a gluconic acid, a citric acid, a tartaric acid, the alkali metal salt of ethylenediaminetetraacetic acid, etc. are mentioned. A commercially available alkali etching treatment agent such as alusatan can also be added. Only one type of these may be used, or two or more types may be used in combination.

The concentration of the base is not particularly limited, but is, for example, 5% by weight to 50% by weight, preferably 8% by weight to 40% by weight, and more preferably 10% by weight to 35% by weight. By increasing the alkali concentration to some extent, the reaction speed with the target can be increased, and a sufficient cleaning effect can be obtained. By reducing the concentration of the alkali to some extent, the oxide layer on the surface of the target can be prevented from being thickened, and the cost can be suppressed.

The temperature of the base to be used is also not particularly limited, and is, for example, 10°C to 80°C, preferably 15°C to 70°C, and more preferably 20°C to 60°C. By increasing the temperature to some extent, the reaction speed with the target can be increased, and a sufficient cleaning effect can be obtained. by taking Lowering the temperature to some extent can prevent the oxide layer on the surface of the target from becoming thicker.

The treatment time with alkali is not particularly limited, but is, for example, 3 minutes or more, preferably 3 minutes to 12 hours, more preferably 5 minutes to 5 hours, and further preferably 5 minutes to 120 minutes. What is necessary is just to determine suitably according to the density|concentration of alkali, temperature, and the thickness of the remaining bonding material.

The treatment with alkali includes applying an alkali solution (preferably an aqueous solution) to a target, or immersing a target in an alkali solution (preferably an aqueous solution).

. acid treatment

If necessary, after the alkali treatment, the bonding surface with the support member in the target may be further treated with an acid ( FIG. 1 ). By the treatment with such an acid, impurities derived from the bonding material or the support member that may remain, which cannot be sufficiently peeled off in the alkali treatment, can be dissolved, and such impurities can be further removed.

Examples of acids usable in the present invention include hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid (hydrofluoric acid), phosphoric acid, perchloric acid, chloric acid, perbromic acid, bromic acid, periodic acid, and iodic acid , hydriodic acid, permanganic acid, tetrafluoroboric acid, etc. If necessary, two or more kinds of acids may be used in combination. As a combination of two or more acids, aqua regia, nitric acid, hydrofluoric acid, or the like can be used.

The concentration of the acid is not particularly limited, but is, for example, 1% by weight to 50% by weight, preferably 5% by weight to 45% by weight, and more preferably 10% by weight to 40% by weight. However, in the case of mixed acids such as nitric acid and hydrofluoric acid, the concentration of one of the acids may be 1% by weight or less.

The temperature of the acid used is also not particularly limited, for example, 10°C to 50°C, It is preferably 15°C to 45°C, more preferably 20°C to 40°C.

The treatment time with acid is not particularly limited, but is, for example, 3 minutes or more, preferably 3 minutes to 12 hours, more preferably 5 minutes to 120 minutes, and further preferably 10 minutes to 90 minutes. It may be appropriately determined according to the concentration of the acid, the temperature, and the thickness of the remaining bonding material.

The treatment with an acid includes applying an acid solution (preferably an aqueous solution) to a target, or immersing a target in an acid solution (preferably an aqueous solution).

By the cleaning method using the used target material, not only impurities originating from the bonding material or the support member can be removed, but also the oxide film existing on the surface of the cleaned target material can be thinned, so that the amount of production required to be described later can be reduced. The amount of dross (dross) generated during the regenerated ingot, or the amount of oxides contained in the regenerated ingot.

. Processing steps

In the case of processing a large number of used targets at the same time, it is preferable to discharge the targets into cage-shaped containers side by side, and immerse each cage-shaped container in an alkali solution or an acid solution, which can be convenient. Insertion and extraction operations into the solution are carried out.

The material of the container may be high in chemical resistance and can bear the weight of the used target material placed therein. Examples of the material of the container include metals or alloys such as stainless steel, titanium, titanium alloys, nickel, nickel alloys, Inconel, and aluminum alloys, resins such as vinyl chloride resins, fluorine resins, polyethylene, and polypropylene. The base or acid to be used may be appropriately selected. When processing a target for flat panel displays with a length of more than 1 m, it is preferable to use stainless steel such as SUS304 and SUS316 from the viewpoint of strength, durability, and chemical resistance. In addition, in the case of selecting a metal container, in order to prevent the metal from being dissolved in the solution, a material coated with the resin or the like can also be used.

In order to immerse each cage-shaped container in the solution, the cage is preferably mesh-shaped, mesh-shaped, punching-shaped, expanded-shaped, or grating-shaped. Since the alkali or acid can diffuse inside and outside the container, the reduction of the reaction rate can be suppressed. In the case of using a metal cage, by reducing the area of the part in contact with the solution, the dissolved amount of the metal component of the cage in the solution can be suppressed, and the contamination caused by the precipitation of the metal component on the target can be suppressed. risks of.

There is no particular limitation on the method for arranging the target material immersed in alkali or acid. Since the bonding material and the like can be removed more efficiently, in the case of a flat target material, it is preferable to incline the side surface of the target material to face downward and to form an angle with respect to the lower surface of the container. 60°~120° for dipping.

When the target material is immersed in alkali or acid, by reacting the bonding material or the target material with the alkali or acid, gas is generated in the form of bubbles, and the gas rises along the surface of the treatment surface, thereby stirring the solution, and in addition , the peeling of the bonding material can be accelerated by the collision of air bubbles.

Since the occurrence of air accumulation can be suppressed and the risk of remaining bonding material can be reduced, in the case of a cylindrical target material, the outer peripheral surface of the target material faces downward and the bonding surface of the target material faces the lower surface of the container. As for the method of the angle, it is preferable to incline 2° to 45° for dipping.

Immediately after the alkali treatment or the acid treatment, jet cleaning can also be performed with a high-pressure fluid of usually 3 MPa or more, preferably 5 MPa or more. The kind of fluid is not particularly limited, but water is preferably used.

The thickness of the bonding material remaining in the target material peeled off from the sputtering target is not uniform, and there are parts with a large thickness. Furthermore, the bonding material melted in the peeling step sags down to the target material, and as a result, there may be a portion where the bonding agent exists in the form of islands or dots on the peeled target material. There is a possibility that the bonding material may remain in these parts after the acid treatment or the alkali treatment. Furthermore, by performing the jet cleaning, the adhered bonding material can be physically removed, so that the risk of remaining bonding material can be reduced.

. Detection of impurities

According to the cleaning method of the target material of the present invention, the amount of impurities derived from the bonding material and the support member can be reduced to the lower detection limit of EDXRF (usually, the lower detection limit varies depending on the element, but the lower detection limit of impurities derived from the bonding material is, for example, is about 0.01 wt %, for example, indium is 0.01 wt %) to a lower value. That is, the processed target material does not substantially contain elements derived from the bonding material and the support member.

Here, the term “impurities” originating in the bonding material or the supporting member means only the main elements constituting the bonding material or the supporting member. The "elements derived from the joining material and the supporting member" refers to the main elements constituting the joining material or the supporting member. This element is usually contained in 0.1 part by mass, preferably 0.5 part by mass or more, and more preferably 1 part by mass or more, with respect to 100 parts by mass of the bonding material or the support member.

The term "substantially free of elements derived from the bonding material and the support member" means that the amount of impurities is reduced to an extent that is smaller than the detection lower limit of EDXRF and cannot be detected by EDXRF.

The cleaning method of the present invention is different from the conventional cleaning method in that the bonding material adhered to the surface can be peeled off in a solid state by more actively dissolving the target material, method of removal.

(Manufacturing method of recycled ingot)

For example, as shown in FIG. 1, a target cleaned in accordance with the present invention is melted or cast, whereby a regenerated ingot can be produced.

As a method of producing a regenerated ingot, it can be produced through a step of melting or casting the target cleaned according to the present invention. Melting or casting can be performed in a known sequence. As a melting method, what is necessary is just to melt|dissolve in the air|atmosphere or vacuum in an electric furnace or a combustion furnace. As the casting method, a continuous casting method, a semi-continuous casting method, a die casting method, an investment casting method, a hot top casting method, a gravity casting method, or the like can be used. Degassing treatment and inclusion removal treatment can also be performed between the steps of melting and casting.

When the metal contained in the target as the main component is aluminum, for example, under vacuum (for example, 0.03 Torr (Torr)) or in the atmosphere, at 670°C to 1200°C, preferably 750°C to 850°C Next, the processed target material is melted in a crucible made of carbon or alumina, stirred in the air if necessary to remove the scum, and cooled in the air to produce a regenerated ingot.

Manufacture of a regenerated ingot can be manufactured only with the target material after cleaning, or you may use the mixture of the existing raw material metal and the target material after cleaning together. In the case of mixing the raw metal and the cleaned target, the mixing ratio of the cleaned target is usually 20% by weight or more, and preferably 50% by weight or more in terms of reducing the raw material cost in the manufacturing cost. .

(recycled ingot)

As described above, the regenerated ingot of the present invention is a regenerated ingot derived from a sputtering target in which a target material mainly containing metal and a support member are bonded together by a bonding material, and does not substantially contain bonding-derived ingots. Elements of material and supporting members. That is, the regenerated ingot of the present invention can have substantially the same composition as the original (unused) target material.

A target having substantially the same composition as the original target can be remanufactured from the regenerated ingot of the present invention. Here, "having substantially the same composition as the original target" means that the main metals (elements) are the same, and the impurities can be contained in the same amount as the impurities originally contained in the original target. The total amount of impurities that can be derived from the bonding material and the support member is, for example, less than 10 ppm, preferably 0.1 ppm to 8 ppm, more preferably 5 ppm or less (or less than), more preferably 0.1 ppm to 5 ppm, and more preferably 0.1 ppm to 5 ppm on a weight basis. 0.1 ppm to 3.5 ppm, more preferably 0.1 ppm to 1.5 ppm. Furthermore, the total amount of total impurities is, for example, less than 50 ppm, preferably 0.1 ppm to 20 ppm, more preferably 0.1 ppm to 10 ppm, still more preferably 5 ppm or less (or insufficient), and still more preferably 0.1 ppm to 5 ppm. The impurities contained in the original target material and the amount thereof can depend on the type of metal contained in the target material as a main component and the method for producing the original target material.

Recycled ingots can also be used for purposes other than targets, and can also be used as raw materials for products requiring high purity, such as aluminum electrolytic condensers, hard disk substrates, corrosion-resistant materials, and high-purity alumina.

When the metal contained in the target material as the main component is aluminum, the total amount of the elements derived from the bonding material and the support member contained in the regenerated ingot is, for example, less than 10 ppm, preferably 0.1 ppm, on a weight basis. ~8ppm, preferably 5ppm Below (or insufficient), more preferably 0.1 ppm to 5 ppm, still more preferably 0.1 ppm to 3.5 ppm, is within the allowable range. Although it is known that the target material made of aluminum for flat panel displays can normally contain about 10 ppm of impurities depending on the application, it is known that the amount of impurities does not particularly affect sputtering.

Since the amount of impurities contained in the regenerated ingot is extremely small, the amount of such impurities can be measured using glow discharge mass spectrometry (GDMS). The lower limit of quantification of GDMS varies depending on the main element of the target and the element to be detected. When the metal contained as the main component of the target is aluminum, it is usually 0.001 ppm to 0.1 ppm, for example, indium is 0.01 ppm.

According to the present invention, the used target can be easily treated and regenerated, and the cleaned target does not substantially contain elements derived from the bonding material and the support member. Therefore, by using the target processed by the said method, the regenerated ingot which has substantially the same composition as the original target can be obtained. Furthermore, a target material having substantially the same composition as the original target material can be easily produced from the regenerated ingot.

Hereinafter, the present invention will be described in detail with reference to examples of the present invention, but the present invention is not limited to the following examples.

[Example]

(Examples 1 to 9 and Comparative Example 1)

The target material was separated from the support plate by heating (280° C.) the bonding layer of the used sputtering target.

In addition, this sputtering target was made of an aluminum flat plate type target (purity 99.999%, Vickers hardness: 15~17, size: 2000mm × 200mm × 15mm) and the support plate made of oxygen-free copper (purity 99.99%, size: 2300mm × 250mm × 15mm) (Sn-Zn-In welding material is used for the metallization of the target). to make.

Furthermore, the welding material adhering to the joint surface of the separated target material is scraped off with a spatula made of silicone, and the welding material is recovered as much as possible. After being separated from the support plate, the target is cut so as to be about 100 mm×200 mm×15 mm.

The targets were washed and processed by immersion under the conditions shown in Tables 1 to 3 (Examples 1 to 9 and Comparative Example 1), respectively, and an EDXRF analyzer (EDX-700L manufactured by Shimadzu Corporation) was used. , detection limit: In is about 0.01 wt %), the bonded surface of the used target after cleaning was analyzed (semi-quantitative analysis) under the following conditions.

At this time, the presence or absence of detection of the X-ray peak was also confirmed regarding the elements of the components of the bonding material and the support plate. As a result, even when the analysis result was 0 wt %, it was also confirmed that no peak was detected.

The EDXRF analysis results are shown in Tables 1 to 3 together with the analysis results of used targets (before cleaning) and unused targets (before bonding).

<Analysis Conditions>

X-ray irradiation diameter: 10mmΦ

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

Current: 100μA

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

Environment: He

Tube: Rh target

filter: none

Measurement method: basic parameter method

Detector: Si(Li) semiconductor detector

As shown in the results of Examples 1 to 9, cleaning by the present invention According to this method, a used target material substantially free of impurities derived from the bonding material and the support plate can be obtained.

In contrast, in Comparative Example 1 in which only the acid treatment was performed, copper (Cu) derived from the support plate could not be removed despite the treatment taking 20 hours. In Examples 1 to 9, at the stage of alkali treatment, the welding material as a joining material could be recovered in a solid state, but in Comparative Example 1, which was treated with an acid, the welding material was dissolved in an acid aqueous solution, The joint material could not be recovered.

Next, a part of the cleaned targets obtained in Example 2, Example 6, Example 7, Example 8, and Comparative Example 1 were collected, and the collected target material was subjected to vacuum (about 0.03 Torr) at 850°C. Target melts. Furthermore, after removing the dross by stirring the obtained melt in the air, it was cooled in the air, whereby a regenerated ingot of about 3 kg was produced.

Using a Glow Discharge Mass Spectrometer (GDMS) (VG9000 manufactured by VG Elemental), the amounts of impurities contained in the regenerated ingots and unused targets were analyzed for In, Sn, and Zn, respectively. , Cu trace analysis. The results are shown in Table 4 and Table 4 together with the analysis results of the ingots produced from the used target (before cleaning), the target of Comparative Example 1, and the unused target (before joining) by the same method. 5.

In Example 2, Example 6, Example 7, and Example 8, the total amount of impurities (ie, In, Sn, Zn, and Cu) derived from the bonding material and the support plate was less than 5 ppm on a weight basis.

In Comparative Example 1, although the treatment took 20 hours, the total amount of impurities (ie, In, Sn, Zn, and Cu) derived from the bonding material and the support plate was about 19 ppm on a weight basis.

(Example 10)

The used flat plate type target (2 t) was treated under the same conditions as in Example 7. However, the size of the target to be cleaned is 1000 mm × 200 mm × 15 mm (will be The target peeled off from the support plate was cut into two halves), placed in a mesh-shaped cage made of SUS304, and immersed in a cleaning solution. At this time, the used target material is arrange|positioned in the cage so that the side surface of the long side of a target may face down, and a bonding surface may stand up (60 degrees - 120 degrees) with respect to the lower surface of a container.

After being immersed in an alkali or an acid, the joint surface is jet-cleaned with high-pressure water of about 5 MPa. After cleaning, 10 pieces of the targets were arbitrarily selected from the treated targets, and an EDXRF analyzer (EDX-700L, detection limit: In was about 0.01% by weight) manufactured by Shimadzu Corporation was used to analyze the bonding surfaces of the cleaned targets. (semi-quantitative analysis). At this time, the presence or absence of detection of the X-ray peak was confirmed with respect to the elements of the bonding material and the components of the support plate. As a result of the analysis, it was also confirmed that no peak was detected when the content was 0%.

Next, the total amount (2 t) of the cleaned target was melted in the atmosphere at 750° C., and the dross was removed by using a flux in the atmosphere, and then the melt was injected into the mold in the atmosphere, and the The melt is cooled, thereby producing a regenerated ingot.

The amount of impurities contained in the regenerated ingot was measured using GDMS (VG9000 manufactured by VG Elemental). The results are shown in Table 5 above.

Also in Example 10, it was not affected by the thickness variation of the welding material of the used target.

When 2 tons of used targets are processed, about 4 kg of welding material can be recovered in a solid state (film form).

[Industrial Availability]

According to the present invention, it is possible to obtain a material that is substantially free from the bonding material and the supporting member. target of impurities. By reproducing an ingot using such a target material as a raw material, a regenerated ingot having substantially the same composition as the original target material substantially free of elements derived from the bonding material and the support member can be obtained. According to the present invention, a target having substantially the same composition as the original target can be produced from such a regenerated ingot. Furthermore, by the cleaning method of the present invention, since the bonding material can be easily recovered in a solid state, it is advantageous for the regeneration of the used target material.

Claims (6)

A method for cleaning a target, which cleans the target of a sputtering target that is formed by combining a target mainly containing metal and a support member with a bonding material and used in sputtering, the bonding material comprising a metal or an alloy thereof selected from the group consisting of indium, tin, zinc, lead, silver, copper, bismuth, cadmium and antimony, the method for cleaning a target comprising: sputtering the target from the sputtering A step of target separation; and a step of treating, with an alkali, a bonding surface with the support member on which the bonding material adheres and remains in the target obtained by the step. The method for cleaning a target material according to claim 1, comprising the following steps: after the step of treating with an alkali, further treating the bonding surface with the support member in the target material with an acid . The method for cleaning a target according to claim 1 or claim 2, wherein the metal is aluminum. A manufacturing method of a target material, which comprises the step of cleaning the target material by the method for cleaning the target material according to any one of the claims 1 to 3 of the patent application scope. A method for producing a regenerated ingot, which includes the step of casting a target cleaned by the method for cleaning a target according to any one of claims 1 to 3. A regenerated ingot, which is produced by the method for producing a regenerated ingot as described in claim 5, and is derived from sputtering in which a target material mainly containing metal and a support member are bonded by a bonding material target, and the regenerated ingot contains aluminum as a main component, derived from the bonding material and the support The total amount of the elements of the support member was less than 10 ppm on a weight basis.

Images