A method for manufacturing a tungsten-titanium-aluminum alloy target

Abstract

This invention provides a method for preparing a tungsten-titanium-aluminum alloy target. The method includes the following steps: ball milling tungsten powder, titanium powder, and aluminum powder under an inert atmosphere to obtain a mixed powder; adding the mixed powder in portions into a hot-pressing mold, performing hot-pressing sintering and post-treatment to obtain the tungsten-titanium-aluminum alloy target. The tungsten-titanium-aluminum alloy target provided by this invention is widely used in the field of high-performance thin film deposition as a diffusion barrier layer to prevent copper atoms from diffusing into the silicon substrate. Furthermore, due to its high thermal stability and low resistivity, it can also be used as a gate or contact electrode.

Description

Technical Field

[0001] This invention relates to the field of metal target preparation technology, and more particularly to a method for preparing a tungsten-titanium-aluminum alloy target. Background Technology

[0002] Tungsten-titanium-aluminum alloy sputtering targets (often written as WTiAl alloy targets) are advanced multi-component alloy sputtering targets. They possess high melting points, thermal stability, high strength and hardness, and relatively high density (compared to pure tungsten), making them suitable for high-temperature sputtering environments and less prone to target surface melting or deformation. Furthermore, the addition of titanium and aluminum improves brittleness, increases toughness, enhances oxidation and corrosion resistance, optimizes plasma coupling efficiency, and reduces particle splashing during the sputtering process.

[0003] Tungsten-titanium-aluminum alloy targets, as an important special alloy material, are widely used in high-performance thin film deposition. They serve as diffusion barrier layers to prevent copper atoms from diffusing into the silicon substrate. Due to their high thermal stability and low resistivity, they can also be used as gate or contact electrodes. Their main function is to form high-performance thin film coatings on the substrate surface using techniques such as physical vapor deposition. Thanks to the synergistic effect of tungsten, titanium, and aluminum, this alloy target material possesses high melting point, high hardness, excellent wear resistance, good corrosion resistance, and high-temperature stability. Its core applications are concentrated in high-end manufacturing and cutting-edge technology fields, such as semiconductors and integrated circuits: used to prepare gate, barrier, or interconnect thin films to meet the stringent requirements of device miniaturization for material conductivity, thermal stability, and reliability; flat panel displays and touch panels: as a coating source for transparent conductive oxide thin films, it helps improve the conductivity, transmittance, and durability of screens; surface engineering and protective coatings: in aerospace, automotive parts, and cutting tools, it coats key components with ultra-hard, high-temperature resistant, and oxidation-resistant reinforced coatings, significantly extending their service life; optical and functional thin films: used to prepare functional thin films with specific optical properties or special electrical and magnetic functions, applied in precision optical components, sensors, and energy storage devices; in addition, in the scientific research field, it is also an important basic material for new material development and thin film technology research. With the continuous upgrading of high-end manufacturing and the semiconductor industry, tungsten-titanium-aluminum alloy sputtering targets are playing an irreplaceable key role due to their comprehensive performance advantages.

[0004] However, current research on the preparation technology of tungsten-titanium-aluminum alloy targets is limited, and the processes are not yet mature. Therefore, how to achieve the preparation of high-quality tungsten-titanium-aluminum alloy targets, simplify the production process, and reduce production costs are technical problems that need to be solved in this field. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for preparing a tungsten-titanium-aluminum alloy target. This tungsten-titanium-aluminum alloy target is widely used in the field of high-performance thin film deposition as a diffusion barrier layer to prevent copper atoms from diffusing into the silicon substrate. At the same time, due to its high thermal stability and low resistivity, it can also be used as a gate or contact electrode.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This invention provides a method for preparing a tungsten-titanium-aluminum alloy target, the method comprising the following steps:

[0008] Tungsten powder, titanium powder, and aluminum powder were ball-milled under an inert atmosphere to obtain a mixed powder.

[0009] The mixed powder is added to a hot pressing mold in several batches, and then subjected to hot pressing sintering and post-treatment to obtain the tungsten-titanium-aluminum alloy target.

[0010] Tungsten-titanium-aluminum alloy sputtering targets are an advanced multi-component alloy sputtering target material. They possess high melting point, thermal stability, high strength and hardness, and relatively high density (compared to pure tungsten), making them suitable for high-temperature sputtering environments and less prone to target surface melting or deformation. Furthermore, the addition of titanium and aluminum improves brittleness, increases toughness, enhances oxidation and corrosion resistance, optimizes plasma coupling efficiency, and reduces particle splashing during the sputtering process.

[0011] The mixed powder is added to the hot press mold in batches. After each batch of powder is added, it needs to be compacted with a tool before the next batch of powder can be added. This is to avoid some areas having less powder, which would result in a larger surface area after sintering and affect subsequent processing.

[0012] Post-processing includes: after cooling, removing the sintered billet from the mold and starting subsequent grinding and wire cutting steps.

[0013] As a preferred technical solution of the present invention, the tungsten powder has a Fisher particle size of 2-5 μm, for example, it can be 2 μm, 3 μm, 4 μm or 5 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0014] Preferably, the titanium powder has a Fisher particle size of 33-37 μm, such as 33 μm, 34 μm, 35 μm, 36 μm or 37 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0015] Preferably, the aluminum powder has a Fisher particle size of 8-12 μm, such as 8 μm, 9 μm, 10 μm, 11 μm or 12 μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0016] As a preferred technical solution of the present invention, the amount of tungsten powder added in the mixed powder is 90-95 parts by mass, for example, 90 parts, 91 parts, 92 parts, 93 parts, 94 parts or 95 parts; the amount of titanium powder added is 3-7 parts, for example, 3 parts, 4 parts, 5 parts, 6 parts or 7 parts; and the amount of aluminum powder added is 0.5-2 parts, for example, 0.5 parts, 1 part, 1.5 parts or 2 parts, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0017] This invention limits the addition amounts of tungsten powder, titanium powder, and aluminum powder in the mixed powder to the aforementioned range. If the aluminum content exceeds this range, the target material will become brittle, affecting subsequent processing: tungsten and titanium have high melting points, while aluminum has a low melting point. When the aluminum content is too high, intermetallic compounds are easily formed during sintering. These compounds have high hardness but poor toughness, making the target material brittle overall and prone to cracking during processing and sputtering; furthermore, electrical and thermal conductivity decreases: the aluminum compounds formed by excessive aluminum have lower conductivity than pure metals; it also leads to deterioration of film performance: excessive aluminum content will change the crystal structure of the film, leading to increased internal stress, causing poor film adhesion or even detachment. If the aluminum content is too low, it will lead to a decrease in oxidation and corrosion resistance.

[0018] As a preferred embodiment of the present invention, the inert atmosphere includes argon and / or nitrogen.

[0019] Preferably, the mixing pressure is 50-200 Pa higher than the external ambient pressure, for example, it can be 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, 100 Pa, 110 Pa, 120 Pa, 130 Pa, 140 Pa, 150 Pa, 160 Pa, 170 Pa, 180 Pa, 190 Pa or 200 Pa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] The powder mixing tank needs to be filled with slightly positive pressure argon gas for protection to prevent the oxygen content of the powder from increasing during the process and affecting the performance of the target material.

[0021] As a preferred technical solution of the present invention, the ball-to-material ratio of the ball mill is 1:(5-7), for example, it can be 1:5, 1:6 or 1:7, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, the grinding balls used in the ball mill include titanium balls of two sizes: D10 and D20.

[0023] Preferably, the mass ratio of the titanium balls of D10 and D20 is 1:(1-3), for example, it can be 1:1, 1:2 or 1:3, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] As a preferred technical solution of the present invention, the hot pressing sintering includes: evacuating to a vacuum level of less than 10. -2 The temperature begins to rise at Pa, and the pressure is slowly increased during the heating process. Once the final temperature is reached, the temperature is held at that temperature. After the holding period ends, the temperature is lowered along with the furnace, and the pressure is slowly reduced at the same time.

[0025] During the hot pressing sintering process, heating and pressurization are carried out simultaneously and completed.

[0026] Preferably, when the temperature is ≤800℃, the heating rate of the hot pressing sintering is 3-4℃ / min, for example, it can be 3℃ / min, 3.5℃ / min or 4℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, when the temperature is >800℃, the heating rate of the hot pressing sintering is 2-3℃ / min, for example, it can be 2℃ / min, 2.5℃ / min or 3℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] As a preferred technical solution of the present invention, the endpoint temperature is 1200-1500 ℃, for example, it can be 1200 ℃, 1300 ℃, 1400 ℃ or 1500 ℃, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0029] As a preferred technical solution of the present invention, the heat preservation time is 3-6 hours, for example, it can be 3 hours, 4 hours, 5 hours or 6 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] As a preferred technical solution of the present invention, the pressure at the endpoint temperature is 30-50 MPa, for example, it can be 30 MPa, 32 MPa, 34 MPa, 36 MPa, 38 MPa, 40 MPa, 42 MPa, 44 MPa, 46 MPa, 48 MPa or 50 MPa, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0031] As a preferred technical solution of the present invention, the pressure is completely released during the pressure reduction process at 800-1000℃, for example, it can be 800℃, 850℃, 900℃, 950℃ or 1000℃, etc., but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0032] After cooling is complete, the sintered billet is removed from the mold, and subsequent grinding and wire cutting steps are performed to obtain a complete WTiAl alloy target billet.

[0033] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0034] Tungsten-titanium-aluminum alloy sputtering targets are an advanced multi-component alloy sputtering targets. They have high melting point, thermal stability, high strength and hardness, and relatively high density (compared to pure tungsten), making them suitable for high-temperature sputtering environments. They are less prone to target surface melting or deformation. The addition of a certain amount of titanium and aluminum can improve brittleness, increase toughness, enhance oxidation and corrosion resistance, optimize plasma coupling efficiency, and reduce particle splashing during the sputtering process. Detailed Implementation

[0035] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0036] In one specific embodiment, the present invention provides a method for preparing a tungsten-titanium-aluminum alloy target, the method comprising the following steps:

[0037] Tungsten powder (2-5 μm Fisher particle size), titanium powder (33-37 μm Fisher particle size), and aluminum powder (8-12 μm Fisher particle size) are ball-milled under an inert atmosphere (argon and / or nitrogen) at a pressure 50-200 Pa higher than the ambient pressure. The amount of tungsten powder added is 90-95 parts by mass, the amount of titanium powder added is 3-7 parts by mass, and the amount of aluminum powder added is 0.5-2 parts by mass to obtain a mixed powder. The ball-to-powder ratio in the ball milling is 1:(5-7), and the mass ratio of D10 and D20 titanium balls used in the ball milling is 1:(1-3).

[0038] The mixed powder is added to a hot-pressing mold in several batches for hot-pressing sintering and post-treatment. The hot-pressing sintering includes: evacuating to a vacuum level of less than 10. -2The heating begins at Pa. When the temperature is ≤800℃, the heating rate of the hot pressing sintering is 3-4℃ / min. When the temperature is >800℃, the heating rate of the hot pressing sintering is 2-3℃ / min. During the heating process, the pressure is slowly increased to 30-50 MPa. When the temperature reaches the final temperature of 1200-1500℃, the holding time is 3-6 h. Heating and pressurization are carried out simultaneously and completed. After the holding time is completed, the furnace is cooled down, and the pressure is slowly reduced to obtain the tungsten-titanium-aluminum alloy target.

[0039] It should be clarified that any use of the process provided in the embodiments of the present invention or any substitution or change of conventional data falls within the protection and disclosure scope of the present invention.

[0040] Example 1

[0041] This embodiment provides a method for preparing a tungsten-titanium-aluminum alloy target, the method comprising the following steps:

[0042] Tungsten powder (Fischer size 3 μm), titanium powder (Fischer size 35 μm), and aluminum powder (Fischer size 9 μm) were ball-milled in an inert atmosphere (argon) 100 Pa higher than the ambient pressure. By mass, 94 parts of tungsten powder, 5 parts of titanium powder, and 1 part of aluminum powder were added to obtain a mixed powder. The ball-to-particle ratio in the ball milling was 1:6, and the mass ratio of D10 to D20 titanium balls used in the ball milling was 1:2.

[0043] The mixed powder is added to a hot-pressing mold in several batches for hot-pressing sintering and post-treatment. The hot-pressing sintering includes: evacuating to a vacuum level of less than 10. -2 The heating begins at Pa. When the temperature is ≤800℃, the heating rate of the hot pressing sintering is 3℃ / min. When the temperature is >800℃, the heating rate of the hot pressing sintering is 3℃ / min. During the heating process, the pressure is slowly increased to 40MPa. When the temperature reaches the final temperature of 1300℃, a 4-hour holding period is started. Heating and pressurization are carried out simultaneously and completed. After the holding period, the furnace is cooled down, and the pressure is slowly reduced to obtain the tungsten-titanium-aluminum alloy target.

[0044] Example 2

[0045] This embodiment provides a method for preparing a tungsten-titanium-aluminum alloy target, the method comprising the following steps:

[0046] Tungsten powder (2 μm Fisher particle size), titanium powder (33 μm Fisher particle size), and aluminum powder (8 μm Fisher particle size) were ball-milled in an inert atmosphere (nitrogen) 50 Pa higher than the ambient pressure. By mass, the amount of tungsten powder added was 90 parts, the amount of titanium powder added was 7 parts, and the amount of aluminum powder added was 0.5 parts to obtain a mixed powder. The ball-to-particle ratio in the ball milling was 1:5, and the mass ratio of D10 and D20 titanium balls used in the ball milling was 1:3.

[0047] The mixed powder is added to a hot-pressing mold in several batches for hot-pressing sintering and post-treatment. The hot-pressing sintering includes: evacuating to a vacuum level of less than 10. -2 The heating begins at Pa. When the temperature is ≤800℃, the heating rate of the hot pressing sintering is 4℃ / min. When the temperature is >800℃, the heating rate of the hot pressing sintering is 2℃ / min. During the heating process, the pressure is slowly increased to 30MPa. The temperature is raised to the final temperature of 1200℃ and then held for 6 hours. Heating and pressurization are carried out simultaneously and completed. After the holding period, the furnace is cooled down, and the pressure is slowly reduced to obtain the tungsten-titanium-aluminum alloy target.

[0048] Example 3

[0049] This embodiment provides a method for preparing a tungsten-titanium-aluminum alloy target, the method comprising the following steps:

[0050] Tungsten powder (5 μm Fisher particle size), titanium powder (37 μm Fisher particle size), and aluminum powder (12 μm Fisher particle size) were ball-milled in an inert atmosphere (argon) 200 Pa higher than the ambient pressure. The amount of tungsten powder added was 95 parts, the amount of titanium powder added was 3 parts, and the amount of aluminum powder added was 2 parts by mass to obtain a mixed powder. The ball-to-particle ratio in the ball milling was 1:7, and the mass ratio of D10 and D20 titanium balls used in the ball milling was 1:1.

[0051] The mixed powder is added to a hot-pressing mold in several batches for hot-pressing sintering and post-treatment. The hot-pressing sintering includes: evacuating to a vacuum level of less than 10. -2 The heating begins at Pa. When the temperature is ≤800℃, the heating rate of the hot pressing sintering is 3℃ / min. When the temperature is >800℃, the heating rate of the hot pressing sintering is 3℃ / min. During the heating process, the pressure is slowly increased to 50MPa. When the temperature reaches the final temperature of 1500℃, a 3-hour holding period is started. Heating and pressurization are carried out simultaneously and completed. After the holding period, the furnace is cooled down, and the pressure is slowly reduced to obtain the tungsten-titanium-aluminum alloy target.

[0052] Example 4

[0053] This embodiment provides a method for preparing a tungsten-titanium-aluminum alloy target. The only difference between this method and Example 1 is that the amount of tungsten powder added is changed to 10 parts, the amount of titanium powder added is 30 parts, and the amount of aluminum powder added is 60 parts. All other aspects are the same as in Example 1.

[0054] Example 5

[0055] This embodiment provides a method for preparing a tungsten-titanium-aluminum alloy target. The only difference between this method and Example 1 is that the amount of tungsten powder added is changed to 85 parts, the amount of titanium powder added is 10 parts, and the amount of aluminum powder added is 5 parts. All other aspects are the same as in Example 1.

[0056] Example 6

[0057] This embodiment provides a method for preparing a tungsten-titanium-aluminum alloy target. The only difference between this method and Example 1 is that the amount of tungsten powder added is changed to 97 parts, the amount of titanium powder added is 2 parts, and the amount of aluminum powder added is 1 part. All other aspects are the same as in Example 1.

[0058] Comparative Example 1

[0059] This comparative example provides a method for preparing a tungsten-titanium-aluminum alloy target. The only difference between this method and Example 1 is that the mixed powder is added to a hot pressing mold in one go and hot pressing sintering is performed. All other aspects are the same as in Example 1.

[0060] Performance testing

[0061] The tungsten-titanium-aluminum targets provided in the examples and comparative examples were subjected to performance tests. The fracture toughness test standard was GB / T 38338-2019 "Method for Determination of Fracture Toughness of Carbon Materials". The results are shown in Table 1.

[0062]

[0063] As shown in Table 1, the multi-component alloy sputtering target provided by this invention can achieve a density of 98.83 g / cm³. 3 The fracture toughness can reach 35 MPa·m 1 / 2 It is well-suited for high-temperature sputtering environments, and is less prone to target surface melting or deformation. The addition of a certain amount of titanium and aluminum can improve brittleness, increase toughness, enhance oxidation and corrosion resistance, optimize plasma coupling efficiency, and reduce particle splashing during the sputtering process.

[0064] A comprehensive comparison of Examples 1 and 4-6 shows that if the amount of tungsten powder, titanium powder, and aluminum powder added to the mixed powder exceeds the preferred range defined in this application, the density and fracture toughness decrease to varying degrees. If the aluminum content is too high, the target material becomes brittle, affecting subsequent processing: tungsten and titanium have high melting points, while aluminum has a low melting point. When the aluminum content is too high, intermetallic compounds are easily formed during sintering. These compounds have high hardness but poor toughness, making the target material brittle overall and prone to cracking during processing and sputtering; furthermore, electrical and thermal conductivity decreases: the aluminum compounds formed by excessive aluminum have lower conductivity than pure metals; it also leads to deterioration of film performance: excessive aluminum content alters the film crystal structure, leading to increased internal stress, resulting in poor film adhesion or even detachment. If the aluminum content is too low, oxidation and corrosion resistance decreases.

[0065] A comprehensive comparison of Example 1 and Comparative Example 1 shows that if the mixed powder is not pre-treated by ball milling and added to the grinding wheel in stages, the density of the prepared sputtering target will be significantly reduced, and the fracture toughness will also be significantly decreased.

[0066] The present invention has been illustrated with the above embodiments to illustrate its detailed structural features. However, the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components used in the present invention, additions of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a tungsten-titanium-aluminum alloy target, characterized in that, The preparation method includes the following steps: Tungsten powder, titanium powder, and aluminum powder were ball-milled under an inert atmosphere to obtain a mixed powder. The mixed powder is added to a hot pressing mold in several batches, and then subjected to hot pressing sintering and post-treatment to obtain the tungsten-titanium-aluminum alloy target.

2. The preparation method according to claim 1, characterized in that, The tungsten powder has a Fisher particle size of 2-5 μm; Preferably, the titanium powder has a Fisher particle size of 33-37 μm; Preferably, the aluminum powder has a Fisher particle size of 8-12 μm.

3. The preparation method according to claim 1 or 2, characterized in that, By mass, the amount of tungsten powder added in the mixed powder is 90-95 parts, the amount of titanium powder added is 3-7 parts, and the amount of aluminum powder added is 0.5-2 parts.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The inert atmosphere includes argon and / or nitrogen; Preferably, the mixing pressure is 50-200 Pa higher than the external ambient pressure.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The ball-to-material ratio of the ball mill is 1:(5-7). Preferably, the grinding balls used in the ball mill include titanium balls of two sizes: D10 and D20. Preferably, the mass ratio of the titanium balls of D10 and D20 is 1:(1-3).

6. The preparation method according to any one of claims 1 to 5, characterized in that, The hot pressing sintering includes: evacuating to a vacuum level of less than 10. -2 The temperature is raised starting at Pa. During the temperature rise, the pressure is slowly increased. Once the final temperature is reached, the temperature is held. After the holding period, the temperature is lowered along with the furnace, and the pressure is slowly reduced at the same time. Preferably, when the temperature is ≤ 800℃, the heating rate of the hot pressing sintering is 3-4℃ / min; Preferably, when the temperature is >800℃, the heating rate of the hot pressing sintering is 2-3℃ / min.

7. The preparation method according to claim 6, characterized in that, The endpoint temperature is 1200-1500 ℃.

8. The preparation method according to claim 6 or 7, characterized in that, The heat preservation time is 3-6 hours.

9. The preparation method according to any one of claims 6 to 8, characterized in that, The pressure at the endpoint temperature is 30-50 MPa.

10. The preparation method according to any one of claims 6 to 9, characterized in that, During the pressure reduction process, the pressure is completely released at 800-1000℃.

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