Preparation method of gold-germanium-nickel alloy evaporation material
By employing variable-speed continuous casting and dual-stage water cooling, the fluidity and expansion issues of AuGeNi alloy during continuous casting were resolved, enabling the continuous casting preparation of AuGeNi alloy bars. This improved production efficiency and compositional uniformity, making the material suitable for large-scale production.
Patent Information
- Application Number
- CN202511864907.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-02-27
AI Technical Summary
Existing technologies make it difficult to prepare AuGeNi alloy vapor deposition materials by continuous casting, mainly because the AuGeNi alloy has poor fluidity and the volume expansion during solidification results in high friction with the crystallizer, which affects the smooth progress of the continuous casting process.
By employing a variable-speed continuous casting method combined with two-stage water cooling, the continuous casting speed and cooling water temperature are adjusted, the crystallizer structure is optimized, and the friction between the AuGeNi alloy and the crystallizer is reduced, thus enabling the continuous casting preparation of AuGeNi alloy.
AuGeNi alloy bars were successfully prepared by continuous casting, simplifying the process, improving production efficiency, ensuring uniformity of alloy composition and consistency of coating, and meeting the needs of large-scale production.
Smart Images
Figure CN121571618A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of precious metal alloy material preparation technology, and relates to a method for preparing a gold-germanium-nickel alloy vapor deposition material. Background Technology
[0002] III-V compound semiconductor devices are widely used in high-tech fields such as aerospace, aviation, and satellite communications due to their excellent high-frequency performance. GaAs devices are among the most technologically mature III-V compound semiconductor devices currently available and have been widely used in electronic circuit systems for solar cells, high-speed integrated circuits, wireless communication equipment, radar, and satellites.
[0003] AuGe alloys are used in GaAs devices to form various multilayer metal coating systems with different metals to create metal-semiconductor ohmic contacts. Studies have found that AuGe alloys have poor wettability on GaAs surfaces. However, when a small amount of Ni (2-11%) is added to AuGe alloys to form AuGeNi alloys, the wettability of the contact surface between AuGeNi and GaAs is significantly improved, thereby greatly enhancing the contact uniformity between the two and helping GaAs devices to fully perform their functions.
[0004] Currently, the bonding of GaAs devices with AuGeNi alloys typically involves a two-stage evaporation process: first, AuGe alloy is deposited, followed by pure Ni metal. The metal film is then heat-treated to form the AuGeNi alloy film. However, evaporation usually requires a high vacuum environment, resulting in a very slow deposition rate (typically measured in micrometers per hour). The equipment is expensive, energy-intensive, and yields very low output per batch, leading to high unit product costs and hindering large-scale production. Furthermore, the precise composition ratio of the AuGeNi alloy depends on the accuracy of controlling the thickness of both the AuGe alloy and Ni layers, which is challenging. Additionally, subsequent... During annealing, solid-state diffusion is required for Ni to penetrate the AuGe layer and react with GaAs. This process is difficult to guarantee in terms of diffusion uniformity in both the lateral and longitudinal directions, which can easily lead to uneven contact cross-sections and uneven contact resistance distribution, affecting the consistency and reliability of device performance. Therefore, it is of great significance to prepare AuGeNi alloy as raw material in advance and then combine the AuGeNi alloy raw material with GaAs through a single vapor deposition. This not only simplifies the process and improves production efficiency, but also makes it easier to control the composition ratio in the alloy, achieving atomic-level uniform mixing at the source and ensuring the consistency and uniformity of the coating.
[0005] Continuous casting is an advanced casting method. Its principle involves rapidly cooling and solidifying molten metal through a crystallizer. The solidified castings are continuously pulled out from the other end of the crystallizer, allowing for castings of any length or a specific length. Compared to other casting methods, continuous casting has unique advantages, such as promoting denser metal crystallization, resulting in a more uniform structure and better mechanical properties. It eliminates the need for risers, thus avoiding the need for trimming the ends of the continuously cast alloy, saving metal, increasing yield, simplifying the process, requiring less production space, and facilitating mechanization and automation. However, due to the addition of Ni to AuGe alloys, the molten metal has poor fluidity. Furthermore, unlike most metals that shrink during solidification, AuGeNi alloys expand during solidification, causing significant friction with the molten metal channels in the crystallizer during continuous casting. This greatly limits the continuous casting of AuGeNi alloys, and may even prevent them from being used as raw materials for vapor deposition.
[0006] Therefore, it is necessary to provide a method for preparing gold-germanium-nickel alloy vapor deposition materials to improve the adaptability of AuGeNi alloy to continuous casting, and thus obtain AuGeNi alloy vapor deposition materials through continuous casting. Summary of the Invention
[0007] To overcome the technical problems in the background art, the present invention optimizes the melt channel structure of the continuous casting crystallizer by combining variable-speed continuous casting of gold-germanium-nickel alloy raw materials, thereby effectively reducing or avoiding the negative impact of the AuGeNi alloy's own characteristics on the continuous casting process, and thus successfully preparing alloy rods by continuous casting. AuGeNi alloy vapor deposition materials can be obtained by subsequent simple shearing and other operations.
[0008] To achieve the above objectives, the present invention is implemented through the following technical solution: This invention proposes a method for preparing a gold-germanium-nickel alloy vapor deposition material, the method comprising the following steps: (1) Pre-melting: Under an inert atmosphere, the gold-germanium-nickel alloy raw material is smelted and then cooled with the furnace to obtain the alloy pre-melted ingot.
[0009] The raw materials for gold-germanium-nickel alloy include Au with a purity of ≥99.99%, Ge with a purity of ≥99.999%, and Ni with a purity of ≥99.999%.
[0010] (2) The alloy pre-melted ingot obtained in step (1) is subjected to variable speed and variable temperature cooling continuous casting to obtain alloy rods.
[0011] (3) Cut the alloy rod obtained in step (2) into granules to obtain alloy particles.
[0012] (4) After polishing, cleaning and drying the alloy particles in step (3) in sequence, gold germanium nickel alloy vapor deposition material is obtained.
[0013] Preferably, in step (1), the inert atmosphere is argon. Before introducing argon, the melting environment is first evacuated to a vacuum level ≤10. -2 Pa, heat the gold-germanium-nickel alloy raw material to 1000-1100℃ to melt it, and then hold it at that temperature for 3-5 minutes.
[0014] Preferably, in step (2), the specific process of variable speed and variable temperature cooling continuous casting includes: firstly, heating the alloy pre-melted ingot to melt and keep it at a constant temperature, then continuously casting at a speed of 200-400 mm / min. When the weight of the continuously cast bar accounts for 2 / 3 of the total weight of the alloy pre-melted ingot, the continuous casting speed is reduced to 50-150 mm / min until the continuous casting is completed. At the same time, during the continuous casting process, when cooling, first use cooling water at 25-30℃, and then use cooling water at 8-10℃.
[0015] Preferably, the alloy pre-melted ingot is heated to 750-950℃ and held for 5-10 minutes before continuous casting begins.
[0016] Preferably, the cooling time using 25~30℃ cooling water is 1:1 compared to the cooling time using 8~10℃ cooling water.
[0017] The crystallizer is one of the core components of continuous casting equipment. It is usually a water-cooled copper mold that defines the cross-sectional shape and size of the cast billet. Cooling water is typically circulated through the crystallizer to cool the molten metal. The crystallizer has a tubular structure and a certain length. This invention only requires changing the existing cooling water pipeline of the crystallizer to two sections: one section carries cooling water at 25-30°C, and the other section carries cooling water at 8-10°C. The rate at which the molten metal passes through the crystallizer remains the same (although there are speed variations during continuous casting in this invention, the crystallizer length is usually short, so the impact of speed variations on the time ratio is negligible). By preset the continuous casting rate and time ratio, the ratio of the length of the molten metal cooled by the 25-30°C cooling water to the length cooled by the 8-10°C cooling water can be calculated. Combined with the total length of the crystallizer during production, the lengths of the crystallizer cooled by the 25-30°C cooling water and the 8-10°C cooling water can be obtained, thus changing the cooling water pipeline to two sections of corresponding length.
[0018] Preferably, in step (4), the alloy particles are magnetically polished at a speed of 270-300 r / min for 1-3 h.
[0019] Preferably, in step (4), the alloy particles are ultrasonically cleaned at an ultrasonic frequency of 80 kHz for 15-40 min.
[0020] Preferably, in step (4), the drying time is 20-40 min and the drying temperature is 50-70℃.
[0021] Preferably, the gold-germanium-nickel alloy comprises, by weight percentage: Ge: 11.4%-12%, Ni: 2%-5%, with the balance being Au.
[0022] The beneficial effects of this invention are: This invention effectively reduces or even avoids the defects of poor fluidity of AuGeNi alloy caused by the addition of Ni element and the increased friction between AuGeNi and the continuous casting crystallizer caused by AuGeNi expansion during continuous casting, which makes it virtually impossible to prepare AuGeNi alloy vapor deposition materials using continuous casting. For the first time, AuGeNi alloy bars were successfully prepared by continuous casting, and AuGeNi alloy vapor deposition materials were finally prepared by subsequent shearing and other methods, successfully expanding the applicability of continuous casting. Attached Figure Description
[0023] Figure 1 This is a photograph of the alloy bars produced by continuous casting according to the present invention. Figure 2 Here is a physical image of the AuGeNi alloy vapor-deposited material prepared according to the present invention; Figure 3 The image shows the microstructure of the AuGeNi alloy vapor-deposited material prepared in this invention. Figure 4 The room temperature tensile curve of the AuGeNi alloy vapor-deposited material prepared in this invention; Figure 5 This is a schematic diagram of the continuous casting process of the present invention; Figure 6 This is a physical image of the AuGeNi alloy vapor-deposited material prepared in Comparative Example 1 of this invention. Detailed Implementation
[0024] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited to the content described.
[0025] The weight percentages of the gold-germanium-nickel alloy composition in Examples 1-3 of this invention are shown in Table 1.
[0026] Table 1 Example 1 This embodiment prepares a gold-germanium-nickel alloy vapor-deposited material according to the following method: (1) Weigh Au with a purity ≥99.99%, Ge with a purity ≥99.999%, and Ni with a purity ≥99.999% according to the alloy composition weight ratio shown in Table 1 and mix them.
[0027] (2) Pre-melting: Add Au, Ge, and Ni raw materials to a high-purity graphite crucible, and evacuate the medium-frequency induction furnace to a vacuum degree ≤10. -2 Pa is filled with high-purity argon gas for protection. A high-purity graphite crucible is placed in a medium-frequency induction furnace and heated to 1050℃ until the Au, Ge, and Ni raw materials melt. The furnace is then held for 5 minutes to ensure uniform mixing. The furnace is then cooled to obtain an alloy pre-melted ingot, which is then removed from the medium-frequency induction furnace.
[0028] (3) Continuous casting: Place the alloy pre-melted ingot in the crucible of the continuous casting equipment, start the continuous casting equipment, heat to 900℃, wait for the alloy pre-melted ingot to melt, hold for 10 minutes, and start continuous casting. The initial continuous casting speed is 200 mm / min. When the weight of the continuously cast bar accounts for 2 / 3 of the total weight of the alloy pre-melted ingot, reduce the continuous casting speed to 100 mm / min until the continuous casting is completed; at the same time, if Figure 5 As shown, during the continuous casting process, cooling water at a temperature of 28°C is introduced into the cooling pipe at the front of the crystallizer and cooling water at a temperature of 9°C is introduced into the cooling pipe at the rear of the crystallizer, in the direction from the inlet to the outlet of the crystallizer. The ratio of the cooling time in the front section to the cooling time in the rear section is 1:1, and alloy bars with a diameter of 4mm are finally obtained.
[0029] (4) Shearing: The alloy rod is sheared into granules according to the required size using a shearing machine to obtain alloy granules.
[0030] (5) Polishing: After shearing, the alloy particles are added to a magnetic polishing bucket, deionized water is added, the polishing speed is set to 288 r / min, and polishing is carried out for 1 hour.
[0031] (6) Cleaning: After polishing, the alloy particles are poured into a cleaning basket and placed on the conveyor belt of a fully automatic ultrasonic cleaner. The cleaning time is set to 30 min, the drying time to 20 min, and the drying temperature to 70℃. The AuGeNi alloy vapor-deposited material prepared in this embodiment is denoted as AuGe12Ni4.
[0032] The alloy rods obtained by continuous casting in this embodiment are as follows: Figure 1 As shown, through Figure 1 It can be seen that the present invention successfully obtained qualified alloy bars through continuous casting.
[0033] The microstructure of AuGe12Ni4 prepared in this embodiment is as follows: Figure 3 As shown, through Figure 3As can be seen, the white areas represent Au-rich solid solutions. Due to the large atomic radius and strong solid solution ability of Au, it forms the matrix phase of the alloy. The gray areas represent Au-Ge intermetallic compounds (such as AuGe2, Au3Ge, etc.), which are typical intermediate phases in AuGeNi alloys. The black areas are mainly Ge-Ni intermetallic compounds (such as NiGe, Ni3Ge, etc.). When Ni is added to the AuGe alloy, it forms coarse GeNi compounds with Ge. As the Ni content increases, the GeNi compounds aggregate and the grains coarsen, which corresponds to the distribution characteristics of the black phase in the image. In summary, this metallographic structure consists of a second phase of intermetallic compounds dispersed on an Au-rich matrix.
[0034] The room temperature tensile properties of the AuGe12Ni4 prepared in this embodiment are as follows: Figure 4 As shown, through Figure 4 As can be seen from the figure, the tensile strength of this material is about 300 MPa and the fracture strain is about 0.8%, which is a brittle or low-plasticity material, consistent with the characteristics of AuGe12Ni4.
[0035] Example 2 This embodiment prepares a gold-germanium-nickel alloy vapor-deposited material according to the following method: (1) Weigh Au with a purity ≥99.99%, Ge with a purity ≥99.999%, and Ni with a purity ≥99.999% according to the alloy composition weight ratio shown in Table 1 and mix them.
[0036] (2) Pre-melting: Add Au, Ge, and Ni raw materials to a high-purity graphite crucible, and evacuate the medium-frequency induction furnace to a vacuum degree ≤10. -2 Pa, filled with high-purity argon gas for protection, placed a high-purity graphite crucible in a medium-frequency induction furnace, heated to 1000℃ until Au, Ge and Ni raw materials melted, held for 3 minutes to mix them evenly, and then cooled with the furnace to obtain an alloy pre-melted ingot, which was then removed from the medium-frequency induction furnace.
[0037] (3) Continuous casting: Place the alloy pre-melted ingot in the crucible of the continuous casting equipment, start the continuous casting equipment, heat to 750℃, wait for the alloy pre-melted ingot to melt, hold for 8 minutes, and start continuous casting. The initial continuous casting speed is 300 mm / min. When the weight of the continuously cast bar accounts for 2 / 3 of the total weight of the alloy pre-melted ingot, reduce the continuous casting speed to 50 mm / min until the continuous casting is completed; at the same time, if Figure 5 As shown, during the continuous casting process, cooling water at a temperature of 25°C is introduced into the cooling pipe at the front of the crystallizer and cooling water at a temperature of 8°C is introduced into the cooling pipe at the rear of the crystallizer, in the direction from the inlet to the outlet of the crystallizer. The ratio of the cooling time in the front section to the cooling time in the rear section is 1:1, and alloy bars with a diameter of 5mm are finally obtained.
[0038] (4) Shearing: The alloy rod is sheared into granules according to the required size using a shearing machine to obtain alloy granules.
[0039] (5) Polishing: After shearing, the alloy particles are added to a magnetic polishing bucket, deionized water is added, the polishing speed is set to 300 r / min, and polishing is carried out for 3 hours.
[0040] (6) Cleaning: After polishing, the alloy particles are poured into a cleaning basket and placed on the conveyor belt of a fully automatic ultrasonic cleaner. The cleaning time is set to 40 min, the drying time to 40 min, and the drying temperature to 50℃. The AuGeNi alloy vapor-deposited material prepared in this embodiment is denoted as AuGe11.4Ni5.
[0041] In this embodiment, AuGeNi alloy rods were successfully prepared by continuous casting, and the AuGe11.4Ni5 prepared in this embodiment has similar properties to the AuGe12Ni4 in Example 1.
[0042] Example 3 This embodiment prepares a gold-germanium-nickel alloy vapor-deposited material according to the following method: (1) Weigh Au with a purity ≥99.99%, Ge with a purity ≥99.999%, and Ni with a purity ≥99.999% according to the alloy composition weight ratio shown in Table 1 and mix them.
[0043] (2) Pre-melting: Add Au, Ge, and Ni raw materials to a high-purity graphite crucible, and evacuate the medium-frequency induction furnace to a vacuum degree ≤10. -2 Pa, filled with high-purity argon for protection, placed a high-purity graphite crucible in a medium-frequency induction furnace, heated to 1100℃ until Au, Ge and Ni raw materials melted, held for 4 minutes to mix them evenly, and then cooled with the furnace to obtain an alloy pre-melted ingot, which was then removed from the medium-frequency induction furnace.
[0044] (3) Continuous casting: Place the alloy pre-melted ingot in the crucible of the continuous casting equipment, start the continuous casting equipment, heat to 950℃, wait for the alloy pre-melted ingot to melt, hold for 5 minutes, and start continuous casting. The initial continuous casting speed is 400 mm / min. When the weight of the continuously cast bar accounts for 2 / 3 of the total weight of the alloy pre-melted ingot, reduce the continuous casting speed to 150 mm / min until the continuous casting is completed; at the same time, if Figure 5 As shown, during the continuous casting process, cooling water at a temperature of 30°C is introduced into the cooling pipe at the front of the crystallizer and cooling water at a temperature of 10°C is introduced into the cooling pipe at the rear of the crystallizer, in the direction from the inlet to the outlet of the crystallizer. The ratio of the cooling time in the front section to the cooling time in the rear section is 1:1, and alloy bars with a diameter of 3mm are finally obtained.
[0045] (4) Shearing: The alloy rod is sheared into granules according to the required size using a shearing machine to obtain alloy granules.
[0046] (5) Polishing: After shearing, the alloy particles are added to a magnetic polishing bucket, deionized water is added, the polishing speed is set to 270 r / min, and polishing is carried out for 2 hours.
[0047] (6) Cleaning: After polishing, the alloy particles are poured into a cleaning basket and placed on the conveyor belt of a fully automatic ultrasonic cleaner. The cleaning time is set to 15 min, the drying time to 30 min, and the drying temperature to 60℃. The AuGeNi alloy vapor-deposited material prepared in this embodiment is denoted as AuGe11.7Ni2.
[0048] In this embodiment, AuGeNi alloy rods were successfully prepared by continuous casting, and the AuGe11.7Ni2 prepared in this embodiment has similar properties to the AuGe12Ni4 in Example 1.
[0049] Comparative Example 1 This comparative example uses the same method as Example 1 to prepare AuGeNi alloy vapor deposition material. The difference is that in this comparative example, the continuous casting process is not slowed down and no temperature-changing cooling is performed. The continuous casting is completed at a speed of 200 mm / min throughout the process, and the cooling temperature is 9°C.
[0050] Due to the poor fluidity of the AuGeNi alloy solution and the significant friction between it and the melt channel in the crystallizer, the amount flowing into the crystallizer is insufficient, and the continuity of the rod is poor, making it impossible to form a complete rod (such as...). Figure 6 (As shown).
[0051] In summary, this invention successfully overcomes the limitations imposed on AuGeNi alloys by their unique properties during continuous casting by employing variable-speed continuous casting combined with variable-temperature cooling, and thus prepares AuGeNi alloy bars through continuous casting.
[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.
Claims
1. A method for preparing a gold-germanium-nickel alloy vapor deposition material, characterized in that: The preparation method includes the following steps: (1) Pre-melting: Under an inert atmosphere, the gold-germanium-nickel alloy raw material is smelted and then cooled in the furnace to obtain a pre-melted alloy ingot. (2) The alloy pre-melted ingot obtained in step (1) is subjected to variable speed and variable temperature cooling continuous casting to obtain alloy bars; (3) Cut the alloy rod obtained in step (2) into granules to obtain alloy particles; (4) After polishing, cleaning and drying the alloy particles in step (3) in sequence, gold germanium nickel alloy vapor deposition material is obtained.
2. The preparation method according to claim 1, characterized in that: In step (1), the inert atmosphere is argon. Before introducing argon, the melting environment is first evacuated to a vacuum level ≤10. -2 Pa, heat the gold-germanium-nickel alloy raw material to 1000-1100℃ to melt it, and then hold it at that temperature for 3-5 minutes.
3. The preparation method according to claim 1, characterized in that: In step (2), the specific process of variable speed and variable temperature cooling continuous casting includes: firstly, heating the alloy pre-melted ingot to melt and keep it at a certain temperature, and then continuously casting at a speed of 200-400 mm / min. When the weight of the continuously cast bar accounts for 2 / 3 of the total weight of the alloy pre-melted ingot, the continuous casting speed is reduced to 50-150 mm / min until the continuous casting is completed. At the same time, during the continuous casting process, when cooling, first use cooling water at 25-30℃, and then use cooling water at 8-10℃.
4. The preparation method according to claim 3, characterized in that: After heating the pre-melted alloy ingot to 750-950℃ and holding it at that temperature for 5-10 minutes, continuous casting begins.
5. The preparation method according to claim 3, characterized in that: The cooling time using 25-30℃ cooling water is 1:1 compared to the cooling time using 8-10℃ cooling water.
6. The preparation method according to claim 1, characterized in that: In step (4), the alloy particles are magnetically polished at a speed of 270-300 r / min for 1-3 h.
7. The preparation method according to claim 1, characterized in that: In step (4), the alloy particles are ultrasonically cleaned at a frequency of 80 kHz for 15-40 minutes.
8. The preparation method according to claim 1, characterized in that: In step (4), the drying time is 20-40 min and the drying temperature is 50-70℃.
9. The preparation method according to any one of claims 1-8, characterized in that: The gold-germanium-nickel alloy comprises, by weight percentage: Ge: 11.4%-12%, Ni: 2%-5%, with the balance being Au.