Aluminum scandium germanium target material and preparation method thereof

Abstract

The present invention provides an aluminum-scandium-germanium target material and a preparation method thereof, belonging to the technical field of metal and alloy target material processing and preparation. This scheme adopts the method of doping germanium into the aluminum-scandium alloy, using a suspension furnace for pre-alloying to lower the metal melting point and avoid excessively high scandium melting point. Then, a medium-frequency furnace is used to cast the aluminum-scandium-germanium target blank in a pollution-free and uniform manner, thereby avoiding direct contamination of the crucible during the doping and smelting process in the medium-frequency furnace. The aluminum-scandium-germanium target material is then deformed and machined to improve surface precision, ultimately producing a high-performance, well-uniformed aluminum-scandium-germanium alloy target material. The addition of germanium not only refines the grain size and increases the density of the target material, but also improves the fluidity of the alloy, greatly improving the castability of the alloy. The addition of germanium not only improves the tensile strength and yield strength of the alloy, making the machining process more efficient and reducing cracking, but also improves physical properties such as conductivity, greatly expanding the application range of back-end products.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal and alloy target material processing and preparation, and particularly relates to an aluminum scandium germanium target material and a preparation method thereof. Background Art

[0002] Aluminum-scandium alloy targets have important applications in semiconductor material preparation. Semiconductor materials are the foundation of modern electronic devices, and targets are one of the key raw materials for their preparation. Aluminum alloy targets are used as sputtering materials to form thin films on substrates using techniques such as physical vapor deposition in a nitrogen atmosphere. The performance of the target directly determines the quality of the film.

[0003] Aluminum-scandium alloy targets are traditionally prepared by the melt-casting method. During the preparation process, the aluminum-scandium alloy targets have large differences in the phase properties of the aluminum-scandium alloy, and the targets themselves are difficult to shape, prone to looseness, cracks and other defects during the melt-casting process. In addition, the tensile strength and yield strength of the aluminum-scandium target themselves are low, which leads to easy cracking during subsequent machining, a small amount of usable part of the finished target, and poor economic benefits. The aluminum-scandium alloy targets prepared by the melt-casting method have coarse and uneven grains, which will also have a great impact on applications such as back-end precision electronic devices.

[0004] The aluminum-scandium target produced by direct melting and casting of the molten ingot has coarse grains, cracks, and other defects. The performance of the target seriously affects the quality of subsequent coatings. Scandium reacts with carbon during high-temperature processes. During the direct melting and doping process in the medium-frequency furnace, it is easily contaminated by the crucible, which will cause the carbon content of the aluminum-scandium target to increase sharply and the scandium content to be about 1%-2% lower. In addition, due to the large differences in the properties of the aluminum-scandium intermediate phase and its poor mechanical properties, the target itself has poor plasticity and high hardness. This makes the aluminum-scandium target more prone to cracking, and cracking occurs during machining, resulting in low utilization and serious waste. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an aluminum-scandium-germanium target material and a preparation method thereof, which adopts the method of doping germanium element into the aluminum-scandium alloy, using a suspension furnace for pre-smelting to ensure the uniformity of the composition, using a casting molding method to cast the aluminum-scandium-germanium target material, and deforming the aluminum-scandium-germanium target material, and machining the surface to improve the accuracy, and finally preparing a high-performance, well-uniform aluminum-scandium-germanium alloy target material.

[0006] To achieve the above object, this solution first provides a method for preparing an aluminum scandium germanium target, comprising the following steps:

[0007] S1. Pre-melting of raw materials: put aluminum, scandium and germanium pure metals into a water-cooled copper crucible in a suspension furnace and evacuate to 10 -2Pa, fill with high-purity argon as protective gas, raise the temperature to above 1600℃, wait until the alloy is completely melted into liquid and there is no obvious solid rolling, then keep warm for 5-10 minutes and cool with the furnace;

[0008] S2, melting and blanking: put the cooled material in S1 into the crucible of medium frequency graphite furnace, and evacuate to 10 -2 Below Pa, fill with high-purity inert protective gas, heat to 1100℃~1300℃ until solution appears in the crucible, continuously measure the melt temperature after the metal is fully melted, and keep the temperature at 1200-1400℃ for 5-30 minutes. After the temperature is kept at 1200-1400℃, cast the target blank immediately after the temperature is finished.

[0009] S3, pressure processing: hot forging the target blank obtained in S2, with a deformation of 3-20%, and finally forming it into a product of a specific shape;

[0010] S4, annealing treatment: annealing treatment is performed on the product after the pressure processing in S3, with the preheating temperature being 200-500°C and the annealing temperature being 500-800°C. After the annealing is completed, the product is cooled in the furnace to obtain a flat ingot;

[0011] S5, precision machining: machining the flat ingot obtained in S4 into the required target product size;

[0012] The aluminum-scandium-germanium target material contains 2-20% atomic percentage of scandium, 1-10% atomic percentage of germanium, and the balance is aluminum.

[0013] Preferably, the purity of the pure metals of aluminum, scandium and germanium in S1 is greater than 3N.

[0014] Preferably, the casting time in S2 is 10-30s.

[0015] Preferably, the hot forging temperature in S3 is 500-800°C.

[0016] Preferably, the preheating time in S4 is 10-30 min, and the annealing time is 60-120 min.

[0017] Based on a general inventive concept, this solution also provides an aluminum scandium germanium target material, wherein the planar size of the aluminum scandium germanium target material is greater than 10 3 mm 2 , relative density greater than 98%, and average grain size less than 100µm.

[0018] The mechanism of preparing aluminum scandium germanium target in this scheme:

[0019] By doping the aluminum-scandium alloy with germanium, pre-melting in a suspension furnace ensures uniformity of composition, and casting the aluminum-scandium-germanium target using a casting method, the target is deformed and machined to improve surface precision, ultimately producing a high-performance, uniform aluminum-scandium-germanium alloy target. The addition of germanium not only refines the grain size and increases the density of the target, but also improves the fluidity of the alloy, greatly enhancing the castability of the alloy. In terms of the alloy's own performance, the addition of germanium not only improves the tensile strength and yield strength of the alloy, making the machining process easier and reducing cracking, but also improves physical properties such as conductivity, greatly expanding the application range of back-end products.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) By adding germanium, the germanium element is finely and evenly dispersed at the grain boundaries of the aluminum-scandium two phases, which plays a role in dispersion strengthening. It effectively refines the grains of the aluminum-scandium target and greatly improves the tensile strength and yield strength of the target. It eliminates casting defects such as looseness and cracks, thereby significantly improving product utilization and reducing cracking during machining, which is conducive to large-scale batch production.

[0022] (2) In addition, grain refinement is conducive to improving the uniformity of the target material, and the homogenization of the target material can directly affect the uniformity of subsequent thin film coating. In addition, the addition of germanium will also increase the conductivity of the target material, which also improves the performance of the target material for back-end precision electronic device applications to a certain extent.

[0023] (3) In addition, to ensure the uniform dispersion of germanium, this proposal optimizes the process flow. The raw materials are pre-melted in a suspension furnace before smelting and casting. This can fully disperse the germanium element in the aluminum-scandium phase, ensure the uniformity of the target blank, and further improve the castability of the alloy. It has strong applicability in the preparation of aluminum-scandium and other alloy target blanks. At the same time, pre-alloying in the suspension furnace can lower the melting point of the metal and avoid crucible contamination caused by the direct smelting process in the medium frequency furnace.

[0024] (4) Pressure processing-annealing treatment can further refine the uniform grains while effectively relieving the internal stress of the aluminum-scandium target and greatly improving the mechanical properties of the target blank. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is the metallographic image of the aluminum-scandium-germanium target prepared in Example 1;

[0027] Figure 2 This is the metallographic image of the aluminum-scandium-germanium target prepared in Comparative Example 1;

[0028] Figure 3 This is the metallographic image of the aluminum scandium germanium target prepared in Comparative Example 2. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0030] The following examples are provided to illustrate the present invention but are not intended to limit the scope of the present invention. Without departing from the spirit and substance of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention are within the scope of the present invention.

[0031] Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art; unless otherwise specified, the reagents used in the examples are commercially available.

[0032] Example 1 Preparation of aluminum scandium germanium target.

[0033] S1. Pre-melting of raw materials: weigh 2kg of aluminum-scandium alloy with a scandium content of 10.03at% and 40g of metallic germanium. The purity of the raw materials is >3N. The suspension furnace crucible uses a water-cooled copper crucible. First, evacuate the suspension furnace to 10 -2 Pa, then fill with high-purity argon to 20kPa, heat and raise the temperature to 1600℃, after the alloy is completely melted into liquid, melt and keep warm for 20 minutes in a suspension melting furnace, and take it out of the furnace after cooling.

[0034] S2, melting and blanking: put the cooled material in S1 into the graphite crucible of the medium frequency furnace, and evacuate the furnace to 10 -2 After the temperature drops below Pa, high-purity argon is filled in as a protective gas; the temperature is raised to 1300°C for smelting, and after full melting, the temperature is kept at 1350°C for 30 minutes before casting, and finally cooled in the corresponding mold to obtain the target blank;

[0035] S3, press working: hot forging the target blank obtained in S2 at a temperature of 600°C, causing the metal material to deform by 5% and finally forming it into a product of a specific shape;

[0036] S4, annealing treatment: After the pressure working is completed, the flat ingot is annealed, with a preheating temperature of 200°C, a preheating time of 30 minutes, an annealing temperature of 500°C, and an annealing time of 120 minutes. After the annealing process is completed, the ingot is cooled in the furnace to obtain the ingot;

[0037] S5. Precision machining: After the ingot is cooled to room temperature, it is precision machined to remove the head and tail. The machining accuracy is ±0.1mm. The diameter of the ingot is measured to be 300mm, the thickness is 7.4mm, and the mass is about 1.586kg.

[0038] Example 2 Preparation of aluminum scandium germanium target.

[0039] S1. Pre-melting of raw materials: weigh 5kg of aluminum-scandium alloy with a scandium content of 15.03at% and 80g of metallic germanium. The purity of the raw materials is >3N. A water-cooled copper crucible is used as the suspension furnace. First, vacuum the suspension furnace to 10 -2 Pa, then fill it with high-purity argon as a protective gas, heat it to 1600℃, smelt it in a suspension melting furnace and keep it warm for 20 minutes, then take it out of the furnace after cooling.

[0040] S2, melting and blanking: put the cooled material in S1 into the crucible of medium frequency graphite furnace, and vacuum the furnace for 10 -2 After the temperature is below Pa, high-purity argon is filled in as a protective gas; the temperature is raised to 1100°C for smelting, and after full melting, the temperature is kept at 1300°C for 30 minutes and then cast in a corresponding mold to obtain a target blank;

[0041] S3, press working: hot forging the target blank obtained in S2 at a temperature of 600°C, causing the metal material to deform by 3% and finally forming it into a product of a specific shape;

[0042] S4, annealing treatment: After the pressure working is completed, the flat ingot is annealed, with a preheating temperature of 200°C, a preheating time of 30 minutes, an annealing temperature of 500°C, and an annealing time of 120 minutes. After the annealing process is completed, the ingot is cooled in the furnace to obtain the ingot;

[0043] S5. Precision machining: After the ingot is cooled to room temperature, it is precision machined to remove the head and tail. The machining accuracy is ±0.1mm. The diameter of the ingot is measured to be 300mm, the thickness is 19.9mm, and the mass is approximately 4.135kg.

[0044] Comparative Example 1 No suspension furnace pre-smelting was used.

[0045] S1. Melting and forming: weigh 5kg of aluminum-scandium alloy with a scandium content of 10.03at% and 40g of metallic germanium. The purity of the raw materials is >3N. Put them into a graphite crucible in a medium frequency furnace and evacuate the furnace to 10 -3 After the temperature is below Pa, high-purity argon is filled in as a protective gas, the temperature is raised to 1600℃ for smelting, and after full melting, the temperature is kept for 30 minutes before casting in the corresponding mold to obtain the target blank;

[0046] S2. Press processing: The target blank obtained in S1 is hot forged at a temperature of 600°C. The metal material is deformed by 5% and finally formed into a product of a specific shape.

[0047] S3, annealing treatment: after the pressure working is completed, the flat ingot is annealed, the preheating temperature is 200 ° C, the preheating time is 30 minutes, the annealing temperature is 500 ° C, the annealing time is 120 minutes, and the ingot is cooled in the furnace after the annealing process is completed;

[0048] S4. Precision machining: After the ingot is cooled to room temperature, it is precision machined to remove the head and tail. The machining accuracy is ±0.1mm. The diameter of the ingot is measured to be 300mm, the thickness is 7.4mm, and the mass is about 1.586kg.

[0049] Comparative Example 2 No germanium element was added.

[0050] No germanium metal was added, and the remaining steps were the same as those in Example 1.

[0051] Experimental Example 1 The performance of the aluminum-scandium-germanium target was investigated.

[0052] The finished product obtained in Example 1 was subjected to metallographic examination and grain size analysis. The plane size was Φ300*7.4mm, the grain size was <100μm, the relative density was greater than 98%, and the sample was taken for purity test. The results showed that the scandium content of the target material was 10.76at%, the purity was >3N, the impurity carbon content was 33ppm, and the total content of other impurities was 115.26ppm, as shown in Table 1 below. The metallographic diagram is as follows: Figure 1 shown.

[0053] The finished product prepared in Comparative Example 1 was subjected to metallographic examination and grain size analysis. The plane size was Φ300*7.4mm, the target material scandium content was 9.05at%, the impurity carbon content was 1382ppm, and the total content of other impurities was 283.35ppm, as shown in Table 1 below; the relative density was greater than 98%, the average grain size was 103μm, and the metallographic diagram was as shown in Table 1 below. Figure 2 shown.

[0054] The finished product obtained in Comparative Example 2 was subjected to metallographic examination and grain size analysis. The plane size was Φ300*7.4mm, the impurity carbon content was 51ppm, and the total content of other impurities was 153.5ppm, as shown in Table 1 below; the relative density was 96%, the average grain size was 156μm, and the metallographic diagram was as shown in Table 1 below. Figure 3 shown.

[0055] Table 1 Analysis of impurity elements in the finished products prepared in Example 1 and Comparative Examples 1-2

[0056]

[0057] The above experimental results show that the casting temperature of the medium frequency furnace in comparative example 1 is significantly increased, and the impurity content is also relatively high. This is because the medium frequency furnace is used for direct alloying and melting without pre-melting in the suspension furnace. On the one hand, due to the different densities of scandium and aluminum, scandium will sink to the bottom, resulting in uneven composition, higher melting point, and the melting temperature needs to be increased. On the other hand, due to the reaction of scandium with carbon during the high temperature process, the carbon content of the aluminum-scandium target will increase sharply, and the scandium content will be about 1%-2% lower. The direct mixing and melting process in the medium frequency furnace is prone to crucible contamination. The use of suspension furnace pre-alloying not only lowers the metal melting point and avoids the scandium melting point being too high, but also makes the scandium aluminum more uniform, reduces the introduction of impurities, and also avoids the occurrence of raw materials sticking to the crucible.

[0058] Compared with Comparative Example 2, Example 1 shows that the addition of germanium affects the target grain size. This is because germanium acts as a nucleus for heterogeneous nucleation during solidification, increasing the number of nucleation sites and reducing the size of grains. Germanium also concentrates at grain boundaries, hindering grain boundary migration and inhibiting grain growth, thereby refining the grains.

[0059] The above is only a preferred embodiment of the present invention, and the scope of protection of the present invention is not limited to the above embodiment. For those skilled in the art, improvements and modifications obtained without departing from the technical concept of the present invention should also be considered as the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum scandium germanium target, characterized in that: The following steps are involved: S1. Pre-melting of raw materials: put aluminum, scandium and germanium pure metals into a water-cooled copper crucible in a suspension furnace and evacuate to 10 -2 Pa, fill with high-purity argon as protective gas, raise the temperature to above 1600℃, wait until the alloy is completely melted into liquid and there is no solid rolling, keep warm for 5-20 minutes and then cool with the furnace; S2, melting and blanking: put the cooled material in S1 into the graphite crucible of the medium frequency furnace, and evacuate to 10 -2 Pa, raise the temperature to 1100℃~1300℃ and a solution appears in the crucible. After the metal is completely melted, the melt temperature is continuously measured. When the melt temperature reaches 1200-1400℃, keep it warm for 5-30 minutes. After the insulation is completed, cast it immediately to obtain the target blank; S3, pressure processing: the target blank prepared in S2 is subjected to 1-5 passes of hot forging with a deformation of 3-20%, and finally formed into a product of a specific shape; S4, annealing treatment: annealing treatment is performed on the product after the pressure processing in S3, with a preheating temperature of 200-500°C and a preheating time of 10-30 minutes, an annealing temperature of 500-800°C and an annealing time of 60-120 minutes, and cooling in the furnace after the annealing to obtain a flat casting billet; S5, precision machining: machining the flat ingot obtained in S4 into the required target product size; The aluminum-scandium-germanium target material contains 2-20% atomic percentage of scandium, 1-10% atomic percentage of germanium, and the balance is aluminum.

2. The preparation method according to claim 1, characterized in that The purity of the aluminum, scandium and germanium pure metals in S1 is greater than 3N.

3. The preparation method according to claim 1, characterized in that The casting time in S2 is 10-30s.

4. The preparation method according to claim 1, characterized in that The hot forging temperature in S3 is 500-800°C.

5. An aluminum scandium germanium target prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The relative density of the aluminum scandium germanium target material is greater than 98%, and the average grain size is less than 100 μm.

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