A high-purity aluminum alloy target material and a method for manufacturing the same

Abstract

The present application relates to magnetron sputtering target material technical field, especially to a kind of high-purity aluminum alloy target material and preparation method thereof, preparation method includes preparation aluminum melt, M melt feeding, alloy smelting and pouring and target preparation.The preparation method of the present application first melts aluminum ingot raw material into aluminum melt using induction smelting, then high-energy beam stream is used to melt the bottom end of high-melting-point M rod material placed directly above induction crucible to form M melt, and high-melting-point metal M is directly added into aluminum melt in liquid form, which is liquid-liquid mixed smelting.In this way, on the one hand, it avoids high-temperature metal sinking to the bottom of the crucible or insufficient reaction, thereby causing the problem of mismatched alloy composition, on the other hand, liquid-liquid mixing can quickly form aluminum alloy melt, thereby greatly reducing the smelting temperature, and avoiding the volatilization of aluminum caused by high temperature and the reaction between the melt and the crucible.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetron sputtering target material, and particularly relates to a high-purity aluminum alloy target material and a preparation method thereof. BACKGROUND

[0002] Aluminum alloy target material has a wide range of applications. For example, aluminum scandium alloy (AlSc) target material reacts to generate aluminum scandium nitride (AlScN) film, which has good piezoelectric properties and is a key material for the preparation of 5G high-frequency filter chips and micro-electro-mechanical system (MEMS) sensors. The film prepared by aluminum titanium alloy (AlTi) target material is used for the work function layer of the HKMG structure of the 45-nanometer advanced process of integrated circuits. Since the thickness of the film is in the order of microns or nanometers, even a small amount of impurities will have a huge impact on the performance of the film device. Therefore, the purity of the aluminum alloy target material usually needs to reach more than 99.99%. Induction melting is the main process for realizing high purification of aluminum alloy target material. However, when the alloy composition contains high-melting-point and high-activity metals such as scandium (Sc), titanium (Ti), zirconium (Zr), erbium (Er), and yttrium (Y), how to realize high purity and high composition uniformity of the aluminum alloy target material is a great challenge for the induction melting process. Because the melting point of aluminum is relatively low, only 660℃, while the melting points of Sc, Ti, Zr, Er and Y are as high as 1500-1900℃, it is difficult for the aluminum melt to quickly and uniformly melt these high-melting-point metals. Moreover, these high-melting-point metals have a higher density than aluminum and have a strong chemical activity. Even if an inert oxide ceramic crucible such as aluminum oxide, magnesium oxide, zirconium oxide, and yttrium oxide or a water-cooled copper crucible is used, these high-activity elemental metals are easy to sink to the bottom of the crucible in the high-temperature molten state, thereby causing the high-activity metals to react with the crucible and introducing impurities and the composition of the alloy melt being non-uniform.

[0003] For such aluminum alloys, there are three methods for conventional induction melting forming process.(1) Solid-solid doping method of elemental raw materials: first form an aluminum melt, and then melt the high-melting-point metals by continuously heating the aluminum melt. However, due to the large difference in melting points, it is difficult for the aluminum melt to quickly react with the high-melting-point metals at low temperature, thereby causing the high-melting-point metals to sink or not to be fully melted. When the temperature of the aluminum melt is continuously increased, the aluminum melt is easy to evaporate, thereby causing the alloy composition to be mismatched or non-uniform. Moreover, the high-temperature melt is easy to react with the crucible and introduce impurities, thereby reducing the purity of the target material.(2) Intermediate alloy method: by adding an intermediate alloy, the melting temperature can be reduced, but the preparation process of the intermediate alloy itself also has problems such as mismatched alloy composition and secondary impurity introduction.(3) Secondary aluminum addition method: first melt the high-melting-point metals, and then add aluminum blocks to melt. The disadvantage of this method is that the high-melting-point elemental metal melt is easy to react with the ceramic crucible and introduce impurities. Even if a water-cooled copper crucible is used, although it can avoid the violent reaction of the melt with the copper crucible, it will introduce trace amounts of copper impurities. In addition, the water-cooled copper crucible has high energy consumption, and it is difficult to avoid the skull at the bottom of the crucible. SUMMARY

[0004] The application provides a high-purity aluminum alloy target material and a preparation method thereof, and aims at solving the problems of alloy composition mismatching or unevenness and secondary impurity introduction in the existing aluminum alloy forming process. The high-melting-point and high-activity alloy elements are added in liquid form for liquid-liquid mixing and melting, so that the problems of difficult melting of alloy elements, easy reaction with the melting crucible to introduce impurities and large alloy composition deviation are solved, and the high-purity aluminum alloy target material with accurate and uniform alloy composition is prepared.

[0005] The application provides a preparation method of a high-purity aluminum alloy target material, which comprises the following steps:

[0006] Step (1) preparation of aluminum melt: the aluminum alloy target material main component aluminum ingot raw material placed in an induction crucible is melted into an aluminum melt by induction melting; wherein the aluminum alloy target material comprises aluminum and metal M, and the mass percentage of the aluminum in the aluminum alloy target material is more than 50%;

[0007] Step (2) M melt feeding: the bottom end of the M rod material placed above the induction crucible is melted by high-energy beam flow, and the formed M melt flows into the aluminum melt formed in the step (1) to form an AlM melt; the electronic weighing sensor connected to the upper end of the M rod material is linked with the high-energy beam flow equipment to realize linkage control, so that the mass of the M melt flowing into the aluminum melt meets the alloy ratio requirement;

[0008] Step (3) alloy melting and pouring: the AlM melt formed in the step (2) is uniformly mixed by adjusting the temperature and stirring conditions of the induction melting, and then poured into a mold to solidify into an alloy ingot;

[0009] Step (4) target material preparation: the alloy ingot obtained in the step (3) is prepared into the aluminum alloy target material.

[0010] In the scheme, the preparation method of the high-purity aluminum alloy target material is prepared by using an induction melting manufacturing method. First, the aluminum ingot raw material is melted into an aluminum melt by using an induction melting method. Then, the high-melting-point M rod material at the bottom end of the high-melting-point M rod material placed above the induction crucible is melted to form an M melt. The high-melting-point metal M is directly added into the aluminum melt in a liquid state, which is liquid-liquid mixing melting. In this way, on the one hand, the problem of alloy composition mismatch caused by high-temperature metal sinking into the crucible or insufficient reaction is avoided. On the other hand, liquid-liquid mixing can quickly form an aluminum alloy melt, thereby greatly reducing the melting temperature and avoiding the volatilization of aluminum caused by high temperature and the reaction of the melt with the crucible. In the preparation method of the present application, in order to accurately control the amount of M melt, an electronic weighing sensor is connected to the upper end of the M rod material to sense the consumption of the M rod material in real time. At the same time, the electronic weighing sensor is connected to the high-energy beam device. When the mass of the M melt flowing into the aluminum melt reaches the weight required by the alloy ratio, the high-energy beam immediately stops heating and melting the M rod material. In addition, the raw material for melting in the preparation method of the present application is high-purity elemental aluminum and high-temperature metal bulk material. Compared with intermediate alloy, crushed powder and other raw materials, bulk metal is easy to be mass-produced with high purity, thereby facilitating the mass production of high-purity aluminum alloy target materials.

[0011] In a possible design, the metal M is one of Sc, Ti, Zr, Er and Y.

[0012] In a possible design, the high-energy beam includes an electron beam, an ion beam or a laser beam. Preferably, the power of the electron beam is 10kw-100kw; the power of the ion beam is 10kw-50kw; and the power of the laser beam is 5kw-50kw.

[0013] It can be understood that the high-melting-point metal M rod material can be effectively melted by selecting an electron beam, an ion beam or a laser beam.

[0014] In a possible design, the purity of the aluminum ingot raw material is not less than 99.999%; and the purity of the M rod material is not less than 99.99%.

[0015] In a possible design, the diameter of the M rod material is 10mm-60mm.

[0016] Alternatively, the diameter of the M rod material can be 10mm, 15mm, 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm or 60mm, etc. It can be understood that by limiting the diameter of the M rod material within a reasonable range, the M solution can flow into the aluminum solution in the form of droplets or liquid flow at a suitable flow rate, thereby achieving the purpose of precise addition.

[0017] In a possible design, the M rod material is located 50mm-150mm above the induction crucible.

[0018] Optionally, the distance between the M rod and the induction crucible can be 50mm, 60mm, 70mm, 80mm, 90mm, 100mm, 110mm, 120mm, 130mm, 140mm or 150mm, etc. It can be understood that by limiting the distance between the M rod and the induction crucible within a reasonable range, the M solution can flow into the aluminum solution at a suitable flow rate, without splashing the AlM molten liquid, avoiding the problem of mismatched or uneven alloy composition, and also avoiding the problem of solidification of the M molten liquid during dripping, avoiding the problem of metal M sinking or insufficient melting. If the distance between the M rod and the induction crucible is less than 50mm, the M molten liquid may splash the AlM molten liquid when it drips into the aluminum solution, and if the distance between the M rod and the induction crucible is greater than 150mm, the M molten liquid may solidify during dripping.

[0019] In one possible design, after the M molten liquid is added in step (2), the remaining length of the upper end of the M rod is not less than 30mm; and a heat-insulating ceramic is arranged between the upper end of the M rod and the electronic weighing sensor, preferably a heat-insulating ceramic block.

[0020] It can be understood that in order to avoid the high-energy beam hitting the electronic weighing sensor and burning it out, the remaining length of the upper end of the M rod after the M molten liquid is added is not less than 30mm. In order to further prevent the high temperature generated by the high-energy beam from damaging the electronic weighing sensor, a heat-insulating ceramic is arranged between the upper end of the M rod and the electronic weighing sensor, which has a heat-insulating effect.

[0021] In one possible design, the electronic weighing sensor has a precision higher than 0.1g; and the electronic weighing sensor is connected with the high-energy beam device that provides the high-energy beam, and when the electronic weighing sensor reaches a set weight value, the high-energy beam device automatically stops heating.

[0022] It can be understood that by limiting the precision of the electronic weighing sensor to be higher than 0.1g, the consumption of the M rod can be more accurately monitored, and at the same time, the electronic weighing sensor is connected with the high-energy beam device, and when the mass of the M molten liquid flowing into the aluminum molten liquid reaches a weight that meets the alloy ratio requirement, the high-energy beam immediately stops heating the M rod.

[0023] In one possible design, in step (1), the atmosphere of the induction melting is an argon gas protection with a purity of 99.999% or higher or a vacuum atmosphere with a pressure of 6x10 -3 Pa.

[0024] It can be understood that, by limiting the atmosphere of the induction melting to argon protection with a purity of 99.999% or higher or a partial pressure of 6*10 -3 Pa vacuum atmosphere, the metals in the alloy can be prevented from being oxidized, and the mismatch or unevenness of the alloy composition can be avoided.

[0025] In one possible design, in the step (1), the material of the induction crucible is inert oxide ceramic; and the inert oxide ceramic includes alumina, magnesia, zirconia or yttria.

[0026] It can be understood that, by reasonably selecting the material of the induction crucible, the high-melting-point elemental metal melt can be effectively prevented from reacting with the crucible to cause the prepared aluminum alloy target to have a mismatch or unevenness of the alloy composition and a reduced purity.

[0027] According to a second aspect of the present application, the present application further provides a high-purity aluminum alloy target prepared by the above preparation method; the purity of the aluminum alloy target is higher than 99.99%; and the deviation of the actual alloy composition of the aluminum alloy target from the nominal composition is less than 0.5%.

[0028] The high-purity aluminum alloy target provided by the present application is prepared by first melting aluminum ingot raw material into aluminum melt by induction melting, and then melting the bottom end of the high-melting-point M rod material placed directly above the induction crucible into M melt by high-energy beam, and the high-melting-point metal M is directly added into the aluminum melt in liquid form, which is liquid-liquid mixing melting. In this way, on the one hand, the high-temperature metal is prevented from sinking to the bottom of the crucible or from being insufficiently reacted, thereby causing a mismatch of the alloy composition; on the other hand, liquid-liquid mixing can quickly form an aluminum alloy melt, thereby greatly reducing the melting temperature and avoiding the volatilization of aluminum caused by high temperature and the reaction of the melt with the crucible to cause impurities. The raw materials for the melting method of the present application are high-purity elemental aluminum and high-temperature metal bulk raw materials. Compared with intermediate alloy, crushed powder raw materials and the like, bulk elemental metal is easy to be mass-produced with high purity, thereby facilitating the mass production of high-purity aluminum alloy targets.

[0029] The high-purity aluminum alloy target provided by the present application has a purity higher than 99.99%, and the deviation of the actual alloy composition of the target from the nominal composition is less than 0.5%. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0031] Figure 1It is a kind of high-purity aluminum alloy target material preparation method provided by the application device schematic diagram.

[0032] Reference signs:

[0033] 1: electronic weighing sensor;2: heat insulation ceramic block;3: M bar stock;4: high-energy beam;5: liquid drop;6: induction smelting furnace;7: mold;8: induction crucible;9: induction coil;10: aluminum melt. DETAILED DESCRIPTION

[0034] To make the purpose, technical scheme and advantages of the present application clearer, the technical scheme in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] Figure 1 The following embodiment shows the device schematic diagram for preparing high-purity aluminum alloy target material.

[0036] Embodiments 1-6

[0037] The embodiment of the present application proposes a preparation method of high-purity aluminum alloy target material, which comprises the following steps:

[0038] (1) Raw material preparation and furnace loading

[0039] The nominal aluminum alloy target material composition is designed according to Table 1 below, the raw materials are weighed, and then loaded into the induction smelting furnace 6. The aluminum ingot raw material with a purity of not less than 99.999% is placed in the induction crucible 8, and the induction coil 9 is arranged outside the induction crucible 8. The induction coil 9 is a power output device, which can adjust the temperature of the induction crucible 8. The metal M bar stock 3 is suspended directly above the induction crucible, and the upper end of the M bar stock is connected with the electronic weighing sensor 1 through the heat insulation ceramic block 2. The metal M is one of Sc, Ti, Zr, Er and Y, the diameter of the M bar stock is φ10mm-60mm, and the purity is not less than 99.99%.

[0040] (2) Preparation of aluminum melt

[0041] The high-purity aluminum ingot raw material of the aluminum alloy target material placed in the induction crucible 8 is melted into an aluminum melt 10 by induction smelting.

[0042] (3) M melt feeding

[0043] The M rod 3 is melted by a high-energy beam 4 of one of an electron beam, an ion beam, and a laser beam, and the M melt is rapidly flowed into the aluminum melt 10 in the induction crucible in the form of a fine stream or droplets 5. The high-energy beam 4 is stopped immediately when the weight of the M melt flowed into the aluminum melt 10 reaches the weight required by the alloy ratio, through the linkage of the electronic weighing sensor 1 connected to the upper end of the M rod 3 and the high-energy beam device. To avoid burning the electronic weighing sensor 1, the remaining length of the M rod 3 at the upper end is not less than 30 mm after the M melt is finished.

[0044] (4) Alloy melting and pouring: The AlM melt is uniformly mixed by appropriately increasing the induction melting temperature and electromagnetic stirring, and the induction melting temperature needs to be higher than the alloy melting point by 50-100°C, and then the alloy melt is rapidly poured into the mold 7 to solidify into an alloy ingot.

[0045] (5) Target material preparation and processing: The alloy ingot is prepared into a high-purity aluminum alloy target material through thermal mechanical treatment, welding, machining, etc.

[0046] The main manufacturing process and performance results in Examples 1-6 are shown in Table 1. The purity of the aluminum alloy target material is tested by using a glow discharge mass spectrometer (GDMS).

[0047] Table 1. Induction melting process parameters and performance results of the aluminum alloy target material in Examples 1-6

[0048]

[0049] As shown in Table 1, the high-melting-point and high-activity alloying element M is added in a liquid state, and the alloying element is melted in a liquid-liquid manner, which solves the problems of difficult melting of the alloying element, easy reaction with the melting crucible to introduce impurities, and large deviation of alloy composition, and can prepare a high-purity aluminum alloy target material with precise and uniform alloy composition. The purity of the aluminum alloy target material is higher than 99.99%, and the deviation of the actual alloy composition of the aluminum alloy target material from the nominal composition is less than 0.5%.

[0050] Comparative Example 1

[0051] Aluminum ingots with a purity of not less than 99.9995% and scandium with a purity of not less than 99.99% are weighed and mixed according to the mass content of scandium of 45%, and then the raw materials are loaded into a zirconia crucible of an induction melting furnace for alloying melting. A low-temperature aluminum melt of 700-800°C is formed in the initial stage, and the high-melting-point scandium is difficult to melt at the bottom of the crucible. The temperature is continuously increased to 1100-1300°C, the aluminum melt is obviously volatilized, and the scandium and aluminum start to melt and react to form an alloy melt. Finally, the alloy melt is rapidly poured into a mold to solidify into an alloy ingot. The test shows that the scandium content in the alloy ingot is 43%, the zirconium impurity in the ingot is increased by 32 ppm (parts per million), and there is a small amount of residual scandium at the bottom of the zirconia crucible.

[0052] Comparative Example 2

[0053] First, aluminum ingots with a purity of not less than 99.999% and titanium with a purity of not less than 99.999% were used as raw materials, and an aluminum-titanium intermediate alloy was prepared by batching and smelting according to a nominal atomic ratio of 50%:50%. The melting point of the alloy was about 1500℃, which was slightly lower than the melting point of pure titanium (1660℃). The measured atomic content of titanium in the aluminum-titanium intermediate alloy was 48.5%, and the introduced impurity increment was 30ppm. Then, aluminum ingots with a purity of not less than 99.9999% and aluminum-titanium intermediate alloy (Al-50at%Ti) with a purity of not less than 99.99% were used as raw materials, and the titanium mass content was weighed and batched at 30%. The raw materials were then loaded into an alumina crucible of an induction smelting furnace for induction smelting, and finally the alloy melt was rapidly poured into a mold to solidify into an alloy ingot. Test results showed that the titanium content in the alloy ingot was 28.8%.

[0054] Comparative Example 3

[0055] Aluminum particles with a purity of not less than 99.9995% and zirconium with a purity of not less than 99.99% were used as raw materials, and the zirconium mass content was weighed and batched at 25%. First, the raw material zirconium was placed in a water-cooled copper crucible for induction smelting to form a high-temperature zirconium melt. Then, aluminum particles were added to the zirconium melt, and the aluminum was rapidly melted to form an aluminum-zirconium alloy melt. Finally, the alloy melt was rapidly poured into a mold to solidify into an alloy ingot. Test results showed that the zirconium content in the alloy ingot was 22%, the copper impurity in the ingot increased by 12ppm, and the residual aluminum-zirconium alloy shell at the bottom of the water-cooled copper crucible accounted for about 12%.

[0056] As can be seen from the results of the examples and comparative examples, compared with the existing method for preparing aluminum alloy targets, the preparation method of the present application can effectively solve the problems of difficult melting of alloy elements, easy reaction with smelting crucibles to introduce impurities, and large deviation of alloy composition, thereby preparing high-purity aluminum alloy targets with precise and uniform alloy composition.

[0057] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not limiting; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method of producing a high purity aluminum alloy target material, characterized by, The method comprises the following steps: Step (1) preparing aluminum melt: using induction melting to melt aluminum alloy target main component aluminum ingot raw material placed in an induction crucible into aluminum melt; wherein, the aluminum alloy target comprises aluminum and metal M, and the mass percentage of the aluminum in the aluminum alloy target is more than 50%; Step (2) M melt feeding: using high-energy beam to melt the bottom end of M rod material placed above the induction crucible, forming M melt flowing into the aluminum melt formed in step (1), forming AlM melt; through the linkage control of the electronic weighing sensor connected to the upper end of the M rod material and the high-energy beam device, the mass of the M melt flowing into the aluminum melt meets the alloy ratio requirement; the high-energy beam comprises an electron beam, an ion beam or a laser beam; the power of the electron beam is 10kw-100kw; the power of the ion beam is 10kw-50kw; the power of the laser beam is 5kw-50kw; Step (3) alloy melting and pouring: after uniformly mixing the AlM melt formed in step (2), pouring it into a mold to solidify into an alloy ingot; Step (4) target preparation: preparing the alloy ingot obtained in step (3) into the aluminum alloy target.

2. The production method according to claim 1, characterized by, The metal M is one of Sc, Ti, Zr, Er and Y.

3. The preparation method according to claim 1, characterized in that, The purity of the aluminum ingot raw material is not less than 99.999%; the purity of the M rod material is not less than 99.99%.

4. The method of claim 1, wherein, The diameter of the M rod material is 10mm-60mm; and / or, the M rod material is located 50mm-150mm above the induction crucible.

5. The preparation method according to claim 1, characterized in that, In step (2), after the M melt feeding is completed, the remaining length of the upper end of the M rod material is not less than 30mm; a heat insulation ceramic is arranged between the upper end of the M rod material and the electronic weighing sensor.

6. The method of claim 1, wherein, The accuracy of the electronic weighing sensor is higher than 0.1g; the electronic weighing sensor and the high-energy beam device have linkage function, when the electronic weighing sensor reaches the set weight value, the high-energy beam device automatically stops heating.

7. The preparation method according to claim 1, characterized in that, In the step (1), the atmosphere of the induction melting is argon protection with purity of 99.999% or higher or vacuum atmosphere with a pressure of 6 x 10 -3 Pa vacuum atmosphere.

8. The method of claim 1, wherein, In step (1), the material of the induction crucible is inert oxide ceramic; the inert oxide ceramic comprises aluminum oxide, magnesium oxide, zirconium oxide or yttrium oxide.

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