Purification and recovery method of oxide residual target

Abstract

The invention provides a purification and recovery method of an oxide residual target, and belongs to the technical field of photoelectric transparent oxide material recovery. The purification and recovery method of the oxide residual target comprises the following steps: sequentially carrying out acid pickling and organic solvent cleaning on the oxide residual target to obtain a pretreated residual target; evaporating the pretreated residual target by adopting a direct-current arc, cooling and recovering to obtain oxide powder; the arc current value of the direct current arc is 500-1200 A, and the arc voltage value of the direct current arc is 50-120 V. Impurities such as label residues, dust and dirt in the production process can be removed through cleaning; by controlling the arc current to be 500-1200A and the arc pressure to be 50-120V, elements such as zirconium, molybdenum, tantalum, tungsten, hafnium and the like are hardly volatilized under the condition, so that the content of the impurity elements in the recycled target material can be reduced, and the purity of the recycled target material is further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling photoelectric transparent oxide materials, and in particular relates to a method for purifying and recycling oxide residual targets. Background Art

[0002] Magnetron sputtering targets refer to materials that are bombarded by high-energy particles during the magnetron sputtering process to produce sputtered atoms or molecules, which are then deposited on the substrate to form a thin film. Magnetron sputtering targets can be divided into metal targets, alloy targets, compound targets (including oxide targets, nitride targets, carbide targets, etc.) and semiconductor targets according to their materials.

[0003] Among them, oxide targets are composite materials prepared by mixing one or more oxides in a certain proportion. Whether it is a flat target or a rotating target, the utilization rate of the target sputtering coating cannot reach 100%, and the remaining unusable part becomes waste target material. In addition, the target material will produce unevenness and size differences during the preparation process, which all need to be processed. The scraps, cuttings, and scrapped products generated during the processing will form a certain amount of waste target material. Waste targets that have undergone processing, coating, and transportation all have various types of impurities to varying degrees, especially zirconium impurities, which have a high content and are difficult to remove, affecting the recycling and reuse of waste targets.

[0004] For example, one prior art discloses a method for recycling IZO targets, which prepares high-density IZO targets by polishing, heat treating, crushing, and heating the waste targets for purification, followed by ball milling, granulation, and molding and sintering. This method can only remove some impurities in the shallow surface layer through polishing and heat treatment, and the subsequent heating and purification is only sintering at high temperature, which cannot effectively remove metal element impurities such as zirconium, and ultimately results in a large difference in the ratio of each element in the recycled target compared to the original target, and cannot be directly used to prepare new targets. Summary of the invention

[0005] The purpose of the present invention is to provide a method for purifying and recovering oxide residual targets. The present invention uses a DC arc to evaporate the cleaned pre-treated residual targets. The distribution ratio of each component in the obtained recovered oxide powder is similar to that of the original oxide target material, and can be directly used to prepare new target materials. In addition, when the preparation method provided by the present invention purifies and recovers oxide targets containing zirconium impurities, the content of zirconium element in the oxide target material can be effectively reduced.

[0006] In order to achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0007] A method for purifying and recovering an oxide residual target comprises the following steps:

[0008] The oxide residual target is sequentially acid-washed and organic solvent-washed to obtain a pre-treated residual target;

[0009] The pre-treated residual target is evaporated by a DC arc, and then recovered to obtain oxide powder after cooling;

[0010] The arc current value of the DC arc is 500-1200A, and the arc voltage value is 50-120V.

[0011] Preferably, the oxide residual target comprises a metal oxide target.

[0012] Preferably, the metal oxide target includes one or more of an indium oxide target, a tin oxide target and an indium tin oxide target.

[0013] Preferably, the acid reagent used for pickling is one or more of hydrochloric acid, nitric acid solution, sulfuric acid solution, citric acid solution and acetic acid solution.

[0014] Preferably, the concentration of the acid reagent is 10-15 wt %, and the pickling time is 5-15 min.

[0015] Preferably, the organic solvent used for the organic solvent cleaning is a small molecule organic ketone and / or a small molecule organic alcohol; and the organic solvent cleaning time is 15 to 40 minutes.

[0016] Preferably, the small molecule ketone is one or more of acetone, butanone, N-methylpyrrolidone, cyclohexanone and acetophenone;

[0017] The small molecule alcohol includes one or more of ethanol, methanol, isopropanol, n-butanol and phenylethanol.

[0018] Preferably, an oxide auxiliary agent is added during the evaporation by the DC arc;

[0019] The composition of the oxide auxiliary agent is the same as that of the oxide residual target, and the purity of the oxide auxiliary agent is ≥99.99%.

[0020] Preferably, the oxide additive accounts for 5-30% of the mass of the oxide residual target.

[0021] The present invention provides a method for purifying and recovering oxide residual targets, comprising the following steps: sequentially acid-washing and organic solvent-washing the oxide residual targets to obtain pre-treated residual targets; evaporating the pre-treated residual targets with a direct current arc, and recovering the oxide powder after cooling; the arc current value of the direct current arc is 500-1200A, and the arc voltage value is 50-120V. The present invention acid-washes the oxide residual targets, which can effectively remove some impurities that are easily soluble in acid; after acid washing, the residual targets are washed with an organic solvent, which can remove some impurities such as label residues, dust and dirt in the production process, and can greatly reduce the impurity content. The present invention can ensure that the components and proportions of the recovered target material are similar to those of the residual target by controlling the arc current within the range of 500-1200A and the arc voltage within the range of 50-120V; and the saturated vapor pressures of zirconium, molybdenum, tantalum, tungsten, hafnium, etc. are all less than 0.005KPa under this condition, and these elements can hardly volatilize. The present invention can reduce the content of the above impurity elements in the recovered target material by maintaining the temperature in the DC arc furnace within the temperature range where the vapor pressure of the above impurity elements is relatively low through the arc current and arc voltage, thereby further improving the purity of the recovered target material.

[0022] In addition, the present invention also includes mixing an oxide auxiliary agent with a pre-treated residual target, and evaporating the mixture using a direct current arc, wherein the components and proportions of the oxide auxiliary agent are the same as those of the oxide residual target. The oxide auxiliary agent used in the present invention has high purity and high specific surface area, and can be quickly heated and melted in an arc furnace. Adding a high-purity auxiliary agent can improve the efficiency of evaporation of the oxide residual target, because compared with the blocky oxide residual target, the powdered oxide auxiliary agent can significantly increase the specific surface area of ​​the target material, and can more efficiently absorb the heat generated by the arc to decompose. The non-oxygen atom vapor is volatilized and recombines with the oxygen atoms in the air to form an oxide, and the oxidation process is an exothermic reaction, which can release more heat, thereby further accelerating the volatilization rate of the oxide residual target, and adding a high-purity oxide auxiliary agent can dilute the content of impurity elements, further improving the purity of the recovered oxide target. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 This is a physical picture of the pre-treated indium tin oxide residual target after cleaning in Example 1;

[0025] Figure 2 This is a physical picture of the indium tin oxide powder recovered in Example 1;

[0026] Figure 3 This is a scanning electron microscope image of the indium tin oxide powder recovered from Example 1;

[0027] Figure 4 This is a particle size distribution curve of the indium tin oxide powder recovered in Example 1. DETAILED DESCRIPTION

[0028] The present invention provides a method for purifying and recovering an oxide residual target, comprising the following steps:

[0029] The oxide residual target is sequentially acid-washed and organic solvent-washed to obtain a pre-treated residual target;

[0030] The pre-treated residual target is evaporated by a DC arc, and then recovered to obtain oxide powder after cooling;

[0031] The arc current value of the DC arc is 500-1200A, and the arc voltage value is 50-120V.

[0032] In the present invention, unless otherwise specified, all raw materials are commercially available products well known to those skilled in the art.

[0033] The present invention sequentially performs acid washing and organic solvent cleaning on the oxide residual target to obtain a pre-treated residual target. In the present invention, the oxide residual target comprises a metal oxide target; the metal oxide target comprises one or more of an indium oxide target, a tin oxide target and an indium tin oxide target, and in a specific embodiment, it may be an indium tin oxide target; the mass ratio of indium oxide to indium oxide in the indium tin oxide target is 90 to 99:1 to 10, and in a specific embodiment, it may be 95:5 or 97:3.

[0034] In the present invention, the acid reagent used for pickling is one or more of hydrochloric acid, nitric acid solution, sulfuric acid solution, citric acid solution and acetic acid solution, and in a specific embodiment, it can be a nitric acid solution; the concentration of the acid reagent is 10-15wt%, and in a specific embodiment, it can be 12wt% or 13wt%; the pickling time is 5-15min, and in a specific embodiment, it can be 8min, 10min or 12min. The present invention can effectively remove some impurities that are easily soluble in acid, such as residual indium element, through pickling.

[0035] The acid washing of the present invention further comprises water washing, and the acid reagent is removed by water washing.

[0036] In the present invention, the organic solvent used for the organic solvent cleaning is a small molecule ketone and / or a small molecule alcohol, the small molecule ketone is one or more of acetone, butanone, N-methylpyrrolidone, cyclohexanone and acetophenone, and in a specific embodiment, it can be acetone; the small molecule alcohol includes one or more of ethanol, methanol, isopropanol, n-butanol and phenylethanol; the organic solvent cleaning time is 15 to 40 minutes, and in a specific embodiment, it can be 20 minutes, 30 minutes or 35 minutes. The present invention can remove impurities such as label residues in some production processes through organic solvent cleaning.

[0037] The organic solvent washing of the present invention further comprises water washing and drying; the water washing removes the organic solvent by water washing; the water washing is ultrasonic cleaning; the frequency of the ultrasonic cleaning is 20 to 50 Khz and the time is 10 to 30 minutes; the present invention has no special limitation on the drying.

[0038] After obtaining the pre-processed residual target, the present invention evaporates the pre-processed residual target by using a direct current arc, and recovers the oxide powder after cooling.

[0039] In the present invention, the arc current value of the DC arc is 500-1200A, and in a specific embodiment, it can be 800A or 1000A; the arc voltage value is 50-120V, and in a specific embodiment, it can be 80 or 100V; the present invention has no special limitation on the time for evaporation of the DC arc, and in the specific embodiments of the present invention, it is instantaneous evaporation, and the time is 1-2s.

[0040] In the present invention, the main factor affecting the content of each element in the recovered target material is the difference in saturated vapor pressure of metal elements in different oxides. The calculation formula for the saturated vapor pressure of each metal is as follows:

[0041] dlnP / d(1 / T)=-H(v) / R*Z(v)

[0042] Among them, H(v), R, and Z(v) are constants that are independent of temperature and only related to material properties. The present invention can ensure that the composition and proportion of the recovered target material are similar to the composition and proportion of the oxide residual target by controlling the arc current within the range of 500-1200A and the arc voltage within the range of 50-120V. In addition, for zirconium, molybdenum, tantalum, tungsten, hafnium, etc., the saturated vapor pressure is less than 0.005KPa at 2500°C. In the range of arc current 500-1200A and arc voltage 50-120V described in the present invention, these elements are almost unable to volatilize. By keeping the temperature within the temperature range where the vapor pressure of the above impurity elements is relatively low, the content of the above impurity elements in the recovered target material can be reduced, and the purity of the recovered target material can be further improved.

[0043] The heat supplied in the DC arc furnace of the present invention can be calculated according to Q1=η*I*U, wherein η represents the efficiency of the arc furnace, I represents the input arc current value, and U represents the input arc voltage value. Therefore, the heat can be controlled by controlling the arc current value and arc voltage value, that is, the temperature of the reaction area can be controlled to achieve the above-mentioned goal of improving the purity of the recovered target material. The present invention introduces an automatic electrode adjustment program, collects parameter signals such as arc current and arc voltage, compares them with the set values, outputs a difference, uses the program to perform calculation conversion on the difference, and outputs a control signal to the electrode lifter. The control signal is used to raise and lower the electrode, thereby realizing the distance between the precise electrode and the oxide residual target to more accurately control the arc current and arc voltage, so as to achieve the temperature of the reaction area within a reasonable range, so as to separate the impurity elements, and at the same time reduce the contact between the electrode and the material, so as to achieve the purpose of further purifying the recovered target material.

[0044] In the present invention, an oxide auxiliary agent is also added during the evaporation by the DC arc; the composition of the oxide auxiliary agent is the same as that of the oxide residual target, and in a specific embodiment, it can be one or more of indium oxide, tin oxide and indium tin oxide; the purity of the oxide auxiliary agent is ≥99.99%; the present invention has no special limitation on the particle size of the oxide auxiliary agent, and it can be in powder form; the oxide auxiliary agent accounts for 5 to 30% of the mass of the oxide residual target, and in a specific embodiment, it can be 8%, 15%, 20% or 23%.

[0045] The oxide additive used in the present invention has high purity and high specific surface area, and can be quickly heated and melted in an electric arc furnace. Adding a high-purity additive can improve the efficiency of oxide residual target evaporation, because compared with block oxide residual target, the powdered oxide additive can significantly increase the specific surface area, and can more efficiently absorb the heat generated by the arc to decompose. And volatilize non-oxygen atomic vapor to recombine with oxygen atoms in the air to form oxides, and the oxidation process is an exothermic reaction, which can release more heat, thereby further accelerating the volatilization rate of the oxide residual target, and adding high-purity oxide additive powder can dilute the content of impurity elements, further improving the purity of the recovered oxide target.

[0046] In the present invention, the cooling is carried out at room temperature and under air / or oxygen conditions, and the present invention has no special limitation on the cooling rate; the collection of the cooling product obtained in the present invention is carried out under negative pressure conditions, and the present invention has no special limitation on the negative pressure conditions; the collection is carried out using a multi-stage powder collection system.

[0047] In order to further illustrate the present invention, the purification and recovery method of the oxide residual target provided by the present invention is described in detail below in combination with the accompanying drawings and examples, but they should not be construed as limiting the protection scope of the present invention.

[0048] Example 1

[0049] The residual indium tin oxide target (the mass ratio of indium oxide to tin oxide is 90:10) is soaked in 12wt% nitric acid for 10 minutes, and then rinsed with deionized water and soaked in an acetone solution for 30 minutes. The residual indium tin oxide target is then ultrasonically cleaned in deionized water for 30 minutes, and the cleaned residual target is dried in an oven to a constant weight to obtain a pretreated residual indium tin oxide target;

[0050] The pretreated indium tin oxide residual target is placed in a crucible of a DC arc furnace, and high-purity indium tin oxide powder accounting for 10% by weight of the dry residual target is added thereto; the DC arc furnace current is set to 800A and the voltage is set to 80V for evaporation, and the mixture is cooled at room temperature and under the action of air, and the powder is collected by a multi-stage powder collection system under negative pressure to obtain indium tin oxide powder.

[0051] Figure 1 This is a physical picture of the pre-treated indium tin oxide residual target after cleaning in Example 1. Figure 2 This is a physical picture of the indium tin oxide powder recovered in Example 1. Figures 1-2 It can be seen that the color of the recovered powder of the indium tin oxide target obtained by the present invention is uniform, which proves that the oxide powder recovered by the present invention has good uniformity and the product has no abnormality.

[0052] Figure 3 This is a scanning electron microscope image of the indium tin oxide powder recovered from Example 1. Figure 3 It can be seen that the recovered powder of the indium tin oxide target obtained in the present invention is mainly nanoscale powder.

[0053] Figure 4 The particle size distribution curve of the indium tin oxide powder recovered in Example 1 is shown in FIG. Figure 4 It can be seen that the recovered powder of the indium tin oxide target obtained by the present invention has a small particle size and is evenly distributed, and is suitable for application in the production of target materials.

[0054] Example 2

[0055] The target material was recovered according to the method described in Example 1, except that the mass ratio of indium oxide to tin oxide in the indium tin oxide residual target was 95:5.

[0056] Example 3

[0057] The target material was recovered according to the method described in Example 1, except that the mass ratio of indium oxide to tin oxide in the indium tin oxide residual target was 97:3.

[0058] Example 4

[0059] The target material was recovered according to the method described in Example 1, except that the mass ratio of indium oxide to tin oxide in the indium tin oxide residual target was 99:1.

[0060] Example 5

[0061] The target material is recovered according to the method described in Example 1, except that the waste target material is a pure indium oxide residual target.

[0062] Example 6

[0063] The target material is recovered according to the method described in Example 1, except that the waste target material is a pure tin oxide residual target.

[0064] Example 7

[0065] The target material was recovered according to the method described in Example 1, except that high-purity indium tin oxide powder was not added.

[0066] Example 8

[0067] The target material is recovered according to the method described in Example 1, except that the arc current value is set to 1200A and the arc voltage value is set to 80V.

[0068] Example 9

[0069] The target material is recovered according to the method described in Example 1, except that the arc current value is set to 800A and the arc voltage value is set to 120V.

[0070] Application Examples

[0071] The recovered powder of the indium tin oxide target obtained in Example 1 is prepared into a target material, and used for magnetron sputtering to obtain a secondary indium tin oxide residual target;

[0072] The secondary indium tin oxide residual target is subjected to direct current arc evaporation according to the recovery method described in Example 1 to obtain secondary recovery indium tin oxide powder;

[0073] The secondary indium tin oxide target material is recovered and powder is prepared into a target material, and after being used for magnetron sputtering, a tertiary indium tin oxide residual target is obtained;

[0074] The tertiary indium tin oxide residual target was subjected to direct current arc evaporation according to the recovery method described in Example 1 to obtain tertiary recovered indium tin oxide powder.

[0075] Test Example 1

[0076] The impurity content of each stage of Examples 1 to 9 was tested by ICP-OES. The test method was as follows: According to the standard "JY-T0567-2020 General Rules for Inductively Coupled Plasma Optical Emission Spectroscopy Analysis Methods", the results are shown in Table 1:

[0077] Table 1 Test results of impurity content at each stage during purification and recovery of Examples 1 to 9

[0078]

[0079] Note: The total impurity content in the residual indium tin oxide target, the residual indium tin oxide target after cleaning and pretreatment, and the recovered indium tin oxide target powder in Table 1 specifically refers to the sum of the contents of the remaining metal elements except indium and tin.

[0080] It can be seen from the results in Table 1 that the ratio of indium to tin in the recovered powder of the indium tin oxide target of the present invention is basically the same as that of the original residual target, which proves that the recovery method of the present invention has high purification efficiency, and the recovered powder obtained has the same ratio of each element as that in the original residual target, and can be directly used to prepare new target materials.

[0081] It can be seen from the results of the above embodiments that different batches of indium tin oxide residual targets all contain a high total impurity content. After pickling, organic solvent immersion and ultrasonic cleaning, some acid-soluble impurities, especially the indium residue used in the binding process, as well as label residues, dust, dirt and other impurities in the production process, can be effectively removed, which can play a role in preliminary removal of obvious dirt. However, it can also be seen that there are still many impurities that cannot be effectively removed after cleaning, especially zirconium impurities that are easily introduced in the production of oxide targets cannot be removed by cleaning steps such as pickling. As shown in Example 7, by adding some high-purity oxides before the reaction, the total impurity element content can be diluted overall, which plays a certain purification role. According to the comparative example, changing the arc conditions does not affect the purification effect, but the higher arc power will affect the particle size and specific surface area of ​​the powder, which has some effect on the application of the product. All embodiments show that by controlling the arc flow and arc pressure within the set range, metal element impurities such as zirconium that are difficult to remove and difficult to volatilize by other methods can be stably and effectively removed.

[0082] Test Example 2

[0083] The impurity content, particle size and specific area of ​​the recycled powder of the indium tin oxide target obtained in Examples 1, 8 and 9, the secondary recycled powder of the indium tin oxide target obtained in Application Example 1, and the tertiary recycled powder of the indium tin oxide target were tested, and the results are shown in Table 2.

[0084] Table 2 Test results of recovered powder of indium tin oxide target obtained in Examples 1, 8 and 9 and Application Example 1

[0085]

[0086] From the results in Table 2, it can be seen that the content of impurity zirconium in the powder obtained after multiple recycling and reprocessing is ≤1ppm, the purity is still very high, and the powder particle size is still in the finer nanopowder, which means that the recycled material still has excellent performance and can be used repeatedly. The preparation method provided by the present invention can maintain a high purity of the recycled target material, which can be directly used to prepare new target material, reducing the cost and having considerable application prospects.

[0087] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for purifying and recovering oxide residual targets, characterized in that: The following steps are involved: The oxide residual target is sequentially acid-washed and organic solvent-washed to obtain a pre-treated residual target; The pre-treated residual target is evaporated by a DC arc, and then recovered to obtain oxide powder after cooling; The arc current value of the DC arc is 500-1200A, and the arc voltage value is 50-120V.

2. The purification and recovery method according to claim 1, characterized in that: The oxide residual target includes a metal oxide target material.

3. The purification and recovery method according to claim 2, characterized in that: The metal oxide target includes one or more of an indium oxide target, a tin oxide target and an indium tin oxide target.

4. The purification and recovery method according to claim 1, characterized in that: The acid reagent used for pickling is one or more of hydrochloric acid, nitric acid solution, sulfuric acid solution, citric acid solution and acetic acid solution.

5. The purification and recovery method according to claim 4, characterized in that: The concentration of the acid reagent is 10-15 wt %, and the pickling time is 5-15 min.

6. The purification and recovery method according to claim 1, characterized in that: The organic solvent used for the organic solvent cleaning is a small molecule organic ketone and / or a small molecule organic alcohol; the organic solvent cleaning time is 15 to 40 minutes.

7. The purification and recovery method according to claim 6, characterized in that: The small molecule ketone is one or more of acetone, butanone, N-methylpyrrolidone, cyclohexanone and acetophenone; The small molecule alcohol includes one or more of ethanol, methanol, isopropanol, n-butanol and phenylethanol.

8. The purification and recovery method according to claim 1, characterized in that: When the DC arc is used for evaporation, an oxide auxiliary agent is also added; The composition of the oxide auxiliary agent is the same as that of the oxide residual target, and the purity of the oxide auxiliary agent is ≥99.99%.

9. The purification and recovery method according to claim 8, characterized in that: The oxide additive accounts for 5-30% of the mass of the oxide residual target.

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