High-purity tantalum rotating target and preparation method thereof

Abstract

The application relates to the technical field of target materials, in particular to a high-purity tantalum rotating target material and a preparation method thereof, which comprises the following components: a main component, tantalum powder; a modified component, 0.001-0.005 wt% of composite doped elements; and the composite doped elements are B and Zr mixed at a mass ratio of 1:2-3. The technical scheme of the application realizes minimization of impurity content, fine grain size, densification of internal structure and complete elimination of internal stress. In sputtering application, the high densification structure reduces particle splashing, the uniform microstructure and good electric conductivity and thermal conductivity improve sputtering stability, and finally the effects of improved sputtering rate, reduced film layer roughness and optimized thickness uniformity are realized, the problems of insufficient densification, poor mechanical property and unstable sputtering effect of the existing target material are effectively solved, and the strict requirements of the high-end film plating field are met.

Description

Technical Field

[0001] This invention relates to the field of target technology, specifically to a high-purity tantalum rotating target and its preparation method. Background Technology

[0002] Tantalum, a rare metal with a high melting point, excellent electrical and thermal conductivity, and chemical stability, is widely used in high-end fields such as semiconductor chip manufacturing, display panel coating, and photovoltaic cell electrode fabrication for its sputtering targets. These applications place extremely high demands on the purity, density, compactness, and mechanical properties of the targets. The degree of compactness of the target directly affects the stability of the sputtering process. If pores or impurities are present, sputtered particles are prone to splashing, causing film defects. Insufficient mechanical properties may lead to deformation or cracking during target installation and high-speed rotating sputtering, affecting production efficiency.

[0003] Currently, the preparation of high-purity tantalum targets faces several challenges: densification is difficult, as conventional sintering processes alone cannot eliminate the porosity between tantalum powder particles, resulting in the target density and compaction failing to meet the requirements of high-end applications; unreasonable doping systems make it difficult to achieve synergistic improvement in grain refinement and densification, and some composite doping schemes, due to improper element ratios, introduce impurity phases or damage the target microstructure; poor process integration, as tantalum powder is prone to secondary oxidation during raw material pretreatment, and mismatch between sintering and plastic processing parameters leads to grain growth and residual internal stress, ultimately affecting the overall performance of the target.

[0004] Therefore, developing a preparation scheme that combines a reasonable doping system with process control to achieve high density and high performance of the target material has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a high-purity tantalum rotating target.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A high-purity tantalum rotating target material includes:

[0008] Main component: tantalum powder;

[0009] Modification components: 0.001-0.005 wt% of composite doping elements are added;

[0010] The composite doping elements are a mixture of B and Zr in a mass ratio of 1:2-3.

[0011] As a further technical solution, the target material density is ≥16.6 g / cm³. 3 Density ≥ 99.8%.

[0012] A method for preparing a high-purity tantalum rotating target includes the following steps:

[0013] S1. Raw material pretreatment: 4N grade tantalum powder was selected and reduced in stages under a hydrogen atmosphere. The molten salt system was a 1:1 mass ratio of NaCl-KCl, and the mass ratio of molten salt to tantalum powder was 2:1. After reduction, the powder was acid-washed with 10% hydrochloric acid for 5-8 minutes, then washed with deionized water until neutral, and dried to constant weight. The staged reduction under hydrogen atmosphere included: Stage 1: 850℃, 0.5kPa hydrogen partial pressure, and holding for 4 hours; Stage 2: 950℃, 2kPa hydrogen partial pressure, and holding for 8 hours.

[0014] S2. Composite doping: Pretreated tantalum powder is mixed with boron oxide-zirconium hydride dopant, first ultrasonically dispersed for 30 min, and then ball-milled for 3 h to obtain mixed powder;

[0015] S3. Sintering and shaping: Vacuum hot pressing sintering is performed to obtain the green body;

[0016] S4. Plastic processing: The billet is cold rolled with a deformation of 60-70%, and then vacuum flattened and annealed at 1100-1200℃ and 0.0001Pa;

[0017] Before cold rolling, ultrasonic pretreatment with power and amplitude gradients was introduced for 30 minutes. The power was increased from 15kHz to 30kHz at a rate of 0.5kHz per minute, and the amplitude was increased from 30μm to 60μm at a rate of 1μm per minute, all simultaneously. The cold rolling die was preheated to 150-200℃ to reduce deformation resistance. Cold rolling was performed in three stages of gradient deformation: the first stage with 30% deformation at a rate of 2mm / s, the middle stage with 20% deformation at a rate of 1.5mm / s, and the final stage with 10-20% deformation at a rate of 1mm / s. The process involves annealing under argon protection in a vacuum at 800℃ between each section, followed by isothermal holding for 1 hour and rapid cooling to room temperature at 5℃ / min. After cold rolling, the material undergoes low-temperature plasma impact and ultrasonic-assisted surface nano-sizing treatments, which refine the overall grain size to 2-4μm, completely eliminating micropores and stress concentration, strengthening grain boundary bonding, and significantly improving the sputtering crack resistance, wear resistance, and long-term service stability of the target material. At the same time, it optimizes the surface density of the sputtered surface, further ensuring the uniformity of film composition and the stability of deposition rate.

[0018] Low-temperature plasma impact, argon atmosphere, 300W power for 10 minutes; ultrasonic-assisted surface nano-treatment, 20kHz ultrasonic and diamond micro powder grinding for 15 minutes, refine the surface grains to 100-200nm.

[0019] S5. Finished product processing: After precision machining, the sputtering surface is mirror polished with a diamond grinding wheel to obtain a sputtering surface Ra≤0.03μm.

[0020] As a further technical solution, in step S1, after acid washing with hydrochloric acid, the tantalum powder is passivated with 0.1 mol / L HF solution for 10 min to prevent secondary oxidation of tantalum powder.

[0021] As a further technical solution, in step S2, the boron oxide-zirconium hydride dopant needs to be vacuum dried at 120°C for 4 hours before being added to remove adsorbed water.

[0022] As a further technical solution, in step S2, the ball milling is carried out at a ball-to-material ratio of 12:1 and a rotation speed of 350 r / min.

[0023] As a further technical solution, in step S2, the frequency of the ultrasonic dispersion is 20kHz.

[0024] As a further technical solution, in step S3, the vacuum degree of the vacuum sintering is 1-1.5 Pa, the sintering temperature is 1300-1800℃, the applied pressure is 40-46 MPa, and the time is 4-5 h.

[0025] As a further technical solution, in step S4, vacuum flattening annealing is performed under pressure of 5-8 MPa for 4-6 hours.

[0026] As a further technical solution, in step S5, after mirror polishing, plasma cleaning is performed with the following parameters: argon gas, power 500W, time 5min.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] 1. This invention significantly improves the overall performance of high-purity tantalum rotating targets by optimizing the target composition and the entire preparation process. Firstly, the combination of raw material pretreatment and the composite doping system lays the foundation for the high performance of the target. Using 4N-grade tantalum powder as the main raw material ensures the basic purity of the target. The staged reduction in a hydrogen atmosphere combined with a NaCl-KCl mixed molten salt system gradually removes impurities such as oxygen and nitrogen from the tantalum powder. Simultaneously, the fluxing effect of the molten salt promotes particle surface activation, creating conditions for subsequent sintering and densification. The HF passivation treatment following hydrochloric acid washing forms a dense oxide film on the tantalum powder surface, effectively preventing secondary oxidation and ensuring the purity of the interparticle bonding. The composite doping element composed of B and Zr in a specific mass ratio exhibits a significant synergistic strengthening effect: B has a small atomic radius and can dissolve into the tantalum lattice to form solid solution strengthening, while also hindering grain growth; Zr can form a stable intermetallic compound with tantalum, acting as dispersed second-phase particles to pin grain boundaries. The combination of the two not only refines the target material grains but also fills the tiny pores between particles, thus solving the problem that single doping cannot simultaneously achieve grain refinement and densification.

[0029] 2. Secondly, the synergistic effect of each step in the preparation process further enhances the structural integrity and performance uniformity of the target material. Vacuum drying at 120℃ before dopant addition avoids impurities caused by moisture introduction; the combination of 20kHz ultrasonic dispersion and ball milling with specific parameters ensures uniform dispersion of the composite dopant elements in the tantalum powder, avoiding performance fluctuations caused by local enrichment or uneven distribution. Optimization of vacuum hot pressing sintering parameters promotes the diffusion and bonding of tantalum powder particles under high temperature and pressure, effectively suppressing porosity formation and achieving high density of the target material in conjunction with the grain refinement effect of composite doping; and the connection between 60-70% deformation cold rolling and 1100-1200℃ vacuum flattening annealing not only further eliminates residual porosity through cold rolling but also eliminates internal stress generated by cold rolling through annealing, optimizing grain orientation and preventing deformation or cracking of the target material due to stress concentration during subsequent use, thereby significantly improving the uniformity of the mechanical properties of the target material.

[0030] 3. Finally, the various steps of the present invention work together to achieve the minimum impurity content, fine grain size, dense internal structure, and complete elimination of internal stress. In sputtering applications, the highly dense structure reduces particle splashing, and the uniform microstructure and good electrical and thermal conductivity improve sputtering stability, ultimately achieving the effects of increased sputtering rate, reduced film roughness, and optimized thickness uniformity. This effectively solves the problems of insufficient densification of existing target materials, poor mechanical properties, and unstable sputtering effects, meeting the stringent requirements of the high-end coating field. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a high-purity tantalum spinning target and its preparation method. The target includes tantalum powder as the main component and composite doping elements as the modified component. The preparation method sequentially includes raw material pretreatment, composite doping, sintering, plastic processing and finished product treatment steps, thereby achieving the characteristics of high density, high compactness and excellent sputtering performance of the target.

[0033] The main raw material is 4N grade tantalum powder, which can be a commercially available product familiar to those skilled in the art.

[0034] The composite doping elements are B and Zr, which are added in the form of boron oxide-zirconium hydride dopant, with the mass ratio of the two controlled between 1:2 and 1:3, and the total amount of dopant added is 0.001wt% to 0.005wt%.

[0035] The molten salt system is composed of NaCl and KCl mixed in a mass ratio of 1:1, with a hydrochloric acid concentration of 10% and an HF solution concentration of 0.1 mol / L. All of the above raw materials are commercially available conventional products with no special restrictions.

[0036] The preparation steps include:

[0037] (S1) Raw material pretreatment:

[0038] 4N grade tantalum powder was selected for staged reduction under a hydrogen atmosphere, with a molten salt to tantalum powder mass ratio of 2:1. Specifically, the staged reduction was performed at 850℃ and 0.5 kPa hydrogen partial pressure for 4 hours, followed by a stage at 950℃ and 2 kPa hydrogen partial pressure for 8 hours. After reduction, the powder was acid-washed with 10% hydrochloric acid for 5 to 8 minutes, and then passivated with 0.1 mol / L HF solution for 10 minutes to prevent secondary oxidation of the tantalum powder. After passivation, the powder was washed with deionized water until neutral and dried to constant weight for later use.

[0039] (S2) Composite doping:

[0040] Before adding the boron oxide-zirconium hydride dopant, it needs to be vacuum dried at 120℃ for 4 hours to remove adsorbed water. The pretreated tantalum powder is mixed with the dried dopant, first ultrasonically dispersed at 20kHz for 30 minutes, and then ball-milled at a ball-to-powder ratio of 12:1 and a speed of 350r / min for 3 hours to obtain the mixed powder.

[0041] (S3) Sintering and shaping:

[0042] The mixed powder is subjected to vacuum hot pressing sintering, with the vacuum degree controlled between 1 Pa and 1.5 Pa, the sintering temperature between 1300℃ and 1800℃, the applied pressure between 40 MPa and 46 MPa, and the holding time between 4 h and 5 h, to obtain the green body.

[0043] (S4) Plastic processing:

[0044] The billet is cold-rolled with a deformation of 60% to 70%, followed by vacuum flattening annealing. The annealing temperature is 1100℃ to 1200℃, the vacuum degree is 0.0001Pa, the pressure is 5MPa to 8MPa, and the holding time is 4h to 6h.

[0045] Before cold rolling, ultrasonic pretreatment with power and amplitude gradients was introduced for 30 minutes. The power was increased from 15kHz to 30kHz at a rate of 0.5kHz per minute, and the amplitude was increased from 30μm to 60μm at a rate of 1μm per minute, all simultaneously. The cold rolling die was preheated to 150-200℃ to reduce deformation resistance. Cold rolling was performed in three stages of gradient deformation: the first stage with 30% deformation at a rate of 2mm / s, the middle stage with 20% deformation at a rate of 1.5mm / s, and the final stage with 10-20% deformation at a rate of 1mm / s. The process involves annealing under argon protection in a vacuum at 800℃ between each section, followed by isothermal holding for 1 hour and rapid cooling to room temperature at 5℃ / min. After cold rolling, the material undergoes low-temperature plasma impact and ultrasonic-assisted surface nano-sizing treatments, which refine the overall grain size to 2-4μm, completely eliminating micropores and stress concentration, strengthening grain boundary bonding, and significantly improving the sputtering crack resistance, wear resistance, and long-term service stability of the target material. At the same time, it optimizes the surface density of the sputtered surface, further ensuring the uniformity of film composition and the stability of deposition rate.

[0046] Low-temperature plasma impact, argon atmosphere, 300W power for 10 minutes; ultrasonic-assisted surface nano-treatment, 20kHz ultrasound and diamond micro-powder grinding for 15 minutes, refines the surface grains to 100-200nm.

[0047] (S5) Finished product processing:

[0048] The annealed billet was precision machined and then mirror-polished with a diamond wheel to achieve a sputtering surface Ra ≤ 0.03 μm. After polishing, plasma cleaning was performed using argon gas as the cleaning medium at a power of 500 W for 5 minutes, ultimately yielding a high-purity tantalum spinning target.

[0049] This invention achieves a target density of 16.6 g / cm³ through a specific composite doping system and process parameters. 3 The above results show a density of no less than 99.8%, while optimizing the grain structure and mechanical properties of the target material, improving the stability of the sputtering process and the quality of the film, and the preparation process is easy to control, making it suitable for industrial production.

[0050] The following are specific examples:

[0051] Example 1: S1 Raw Material Pretreatment: 4N grade tantalum powder was selected, and a NaCl-KCl mixed molten salt (mass ratio 1:1) was added at a molten salt to tantalum powder mass ratio of 2:1. A staged reduction under a hydrogen atmosphere was performed: the first stage was held at 850℃ and 0.5 kPa hydrogen partial pressure for 4 hours, and the second stage was held at 950℃ and 2 kPa hydrogen partial pressure for 8 hours. After reduction, the sample was acid-washed with 10% hydrochloric acid for 6 minutes, then passivated with 0.1 mol / L HF solution for 10 minutes, washed with deionized water until neutral, and dried to constant weight.

[0052] S2 composite doping: Weigh boron oxide-zirconium hydride dopant (B to Zr mass ratio 1:2.5) and vacuum dry at 120℃ for 4 hours. Mix the dopant with pretreated tantalum powder at a total doping amount of 0.003wt%, ultrasonically disperse at 20kHz for 30 minutes, and then ball mill at a ball-to-powder ratio of 12:1 and a speed of 350r / min for 3 hours to obtain a mixed powder.

[0053] S3 sintering: The mixed powder is placed in a sintering furnace, the vacuum degree is controlled at 1.2Pa, the temperature is raised to 1500℃, a pressure of 43MPa is applied, and the temperature is held for 4.5h to obtain the green body.

[0054] S4 Plastic processing: The billet is cold rolled with a deformation of 65%, and then vacuum flattening annealing is completed by applying a pressure of 6MPa for 5 hours under vacuum conditions of 1150℃ and 0.0001Pa.

[0055] Before cold rolling, a power gradient and amplitude gradient ultrasonic-assisted pretreatment is introduced for 30 minutes. The power is increased from 15kHz to 30kHz at a rate of 0.5kHz per minute, and the amplitude is increased from 30μm to 60μm at a rate of 1μm per minute, all simultaneously. The cold rolling die is preheated to 150℃ to reduce deformation resistance. Cold rolling is carried out in three stages of gradient deformation: the first stage has a deformation amount of 30% at a rate of 2mm / s, the middle stage has a deformation amount of 20% at a rate of 1.5mm / s, and the last stage has a deformation amount of 15% at a rate of 1mm / s. Between each stage, the stress-relief annealing is carried out under argon protection at 800℃, followed by isothermal holding for 1 hour and then rapid cooling to room temperature at a rate of 5℃ / min. After cold rolling, the surface is subjected to low-temperature plasma impact and ultrasonic-assisted nano-sizing treatment, which can refine the overall grain to 2-4μm.

[0056] Low-temperature plasma impact, argon atmosphere, 300W power for 10 minutes; ultrasonic-assisted surface nano-treatment, 20kHz ultrasound and diamond micro-powder grinding for 15 minutes, refines the surface grains to 100-200nm.

[0057] S5 Finished Product Processing: After precision machining, the sputtering surface is mirror-polished with a diamond wheel to achieve a sputtering surface Ra=0.025μm. Argon plasma cleaning is then performed at a power of 500W for 5 minutes to obtain a high-purity tantalum spinning target.

[0058] Example 2: S1 Raw Material Pretreatment: 4N grade tantalum powder was selected, and a NaCl-KCl mixed molten salt (mass ratio 1:1) was added at a molten salt to tantalum powder mass ratio of 2:1. A staged reduction under a hydrogen atmosphere was performed: the first stage was held at 850℃ and 0.5 kPa hydrogen partial pressure for 4 hours, and the second stage was held at 950℃ and 2 kPa hydrogen partial pressure for 8 hours. After reduction, the sample was acid-washed with 10% hydrochloric acid for 5 minutes, then passivated with 0.1 mol / L HF solution for 10 minutes, washed with deionized water until neutral, and dried to constant weight.

[0059] S2 composite doping: Weigh boron oxide-zirconium hydride dopant (B to Zr mass ratio 1:2) and vacuum dry at 120℃ for 4 hours. Mix the dopant with pretreated tantalum powder at a total doping amount of 0.001wt%, ultrasonically disperse at 20kHz for 30 minutes, and then ball mill at a ball-to-powder ratio of 12:1 and a speed of 350r / min for 3 hours to obtain a mixed powder.

[0060] S3 sintering: The mixed powder is placed in a sintering furnace, the vacuum degree is controlled at 1 Pa, the temperature is raised to 1300℃, a pressure of 40 MPa is applied, and the temperature is held for 4 hours to obtain the green body.

[0061] S4 Plastic processing: The billet is cold rolled with a deformation of 60%, and then vacuum flattening annealing is completed by applying a pressure of 5MPa for 4 hours under vacuum conditions of 1100℃ and 0.0001Pa.

[0062] Before cold rolling, a power gradient and amplitude gradient ultrasonic-assisted pretreatment is introduced for 30 minutes. The power is increased from 15kHz to 30kHz at a rate of 0.5kHz per minute, and the amplitude is increased from 30μm to 60μm at a rate of 1μm per minute, all simultaneously. The cold rolling die is preheated to 160℃ to reduce deformation resistance. Cold rolling is carried out in three stages of gradient deformation: the first stage has a deformation amount of 30% at a rate of 2mm / s, the middle stage has a deformation amount of 20% at a rate of 1.5mm / s, and the last stage has a deformation amount of 10% at a rate of 1mm / s. Between each stage, the stress-relief annealing is carried out under argon protection at 800℃, followed by isothermal holding for 1 hour and then rapid cooling to room temperature at a rate of 5℃ / min. After cold rolling, the surface is subjected to low-temperature plasma impact and ultrasonic-assisted nano-sizing treatment, which can refine the overall grain to 2-4μm.

[0063] Low-temperature plasma impact, argon atmosphere, 300W power for 10 minutes; ultrasonic-assisted surface nano-treatment, 20kHz ultrasound and diamond micro-powder grinding for 15 minutes, refines the surface grains to 100-200nm.

[0064] S5 Finished Product Processing: After precision machining, the sputtering surface is mirror-polished with a diamond wheel to achieve a sputtering surface Ra=0.028μm. Argon plasma cleaning is then performed at a power of 500W for 5 minutes to obtain a high-purity tantalum spinning target.

[0065] Example 3: S1 Raw Material Pretreatment: 4N grade tantalum powder was selected, and a NaCl-KCl mixed molten salt (mass ratio 1:1) was added at a molten salt to tantalum powder mass ratio of 2:1. A staged reduction under a hydrogen atmosphere was performed: the first stage was held at 850℃ and 0.5 kPa hydrogen partial pressure for 4 hours, and the second stage was held at 950℃ and 2 kPa hydrogen partial pressure for 8 hours. After reduction, the sample was acid-washed with 10% hydrochloric acid for 8 minutes, then passivated with 0.1 mol / L HF solution for 10 minutes, washed with deionized water until neutral, and dried to constant weight.

[0066] S2 composite doping: Weigh boron oxide-zirconium hydride dopant (B to Zr mass ratio 1:3) and vacuum dry at 120℃ for 4 hours. Mix the dopant with pretreated tantalum powder at a total doping amount of 0.005wt%, ultrasonically disperse at 20kHz for 30 minutes, and then ball mill at a ball-to-powder ratio of 12:1 and a speed of 350r / min for 3 hours to obtain a mixed powder.

[0067] S3 sintering: The mixed powder is placed in a sintering furnace, the vacuum degree is controlled at 1.5Pa, the temperature is raised to 1800℃, a pressure of 46MPa is applied, and the temperature is held for 5h to obtain the green body.

[0068] S4 Plastic processing: The billet is cold rolled with 70% deformation, and then vacuum flattening annealing is completed by applying 8MPa pressure and holding for 6 hours under vacuum conditions of 1200℃ and 0.0001Pa.

[0069] Before cold rolling, a power gradient and amplitude gradient ultrasonic-assisted pretreatment is introduced for 30 minutes. The power is increased from 15kHz to 30kHz at a rate of 0.5kHz per minute, and the amplitude is increased from 30μm to 60μm at a rate of 1μm per minute, all simultaneously. The cold rolling die is preheated to 200℃ to reduce deformation resistance. Cold rolling is carried out in three stages of gradient deformation: the first stage has a deformation amount of 30% at a rate of 2mm / s, the middle stage has a deformation amount of 20% at a rate of 1.5mm / s, and the last stage has a deformation amount of 20% at a rate of 1mm / s. Between each stage, the stress-relief annealing is carried out under argon protection at 800℃, followed by isothermal holding for 1 hour and then rapid cooling to room temperature at a rate of 5℃ / min. After cold rolling, the surface is subjected to low-temperature plasma impact and ultrasonic-assisted nano-sizing treatment, which can refine the overall grain to 2-4μm.

[0070] Low-temperature plasma impact, argon atmosphere, 300W power for 10 minutes; ultrasonic-assisted surface nano-treatment, 20kHz ultrasound and diamond micro-powder grinding for 15 minutes, refines the surface grains to 100-200nm.

[0071] S5 Finished Product Processing: After precision machining, the sputtering surface is mirror-polished with a diamond wheel to achieve a sputtering surface Ra=0.022μm. Argon plasma cleaning is then performed at a power of 500W for 5 minutes to obtain a high-purity tantalum spinning target.

[0072] Comparative Example 1: Mixing treatment: Without adding any dopants, the pretreated tantalum powder was directly ultrasonically dispersed at 20 kHz for 30 min, and then ball-milled at a ball-to-powder ratio of 12:1 and a speed of 350 r / min for 3 h to obtain powder.

[0073] The remaining steps are exactly the same as in Example 1.

[0074] Comparative Example 2: Composite doping: Boron oxide was selected as the dopant and dried under vacuum at 120°C for 4 hours. It was then mixed with pretreated tantalum powder at an addition rate of 0.003 wt%. The subsequent ultrasonic dispersion and ball milling parameters were the same as in Example 1.

[0075] The remaining steps are exactly the same as in Example 1.

[0076] Comparative Example 3: Raw material pretreatment: 4N grade tantalum powder was selected, and a NaCl-KCl mixed molten salt (mass ratio 1:1) was added at a molten salt to tantalum powder mass ratio of 2:1. A staged reduction under a hydrogen atmosphere was performed, with parameters consistent with Example 1. After reduction, the powder was only acid-washed with 10% hydrochloric acid for 6 minutes, without HF passivation treatment, and directly washed with deionized water until neutral before drying to constant weight.

[0077] The remaining steps are exactly the same as in Example 1.

[0078] Comparative Example 4: No pre-cold rolling treatment was performed during plastic processing; the remaining steps were exactly the same as in Example 1.

[0079] test:

[0080] Experiment 1: Density and compaction test;

[0081] According to GB / T23561.2-2023, the density and compactness of the target material were determined using the Archimedes displacement method. Each sample was tested three times, and the average value was taken. The results are as follows:

[0082] Table 1

[0083]

[0084] As shown in Table 1, the densities of Examples 1-3 are all ≥16.6 g / cm³. 3 The density was ≥99.8%. In Comparative Example 1, due to the lack of composite doping elements, the tantalum powder grains grew significantly during sintering, making it difficult to fill the pores, resulting in a significant decrease in density and compactness.

[0085] Experiment 2: Mechanical property testing;

[0086] Hardness test: Refer to GB / T3851-2015, use a Vickers hardness tester, test load 5kg, hold time 15s, test 5 points for each sample, and take the average value.

[0087] Bending strength test: Referring to GB / T6569-2017, the three-point bending method was used. The sample size was 3mm×4mm×36mm, the span was 30mm, the loading rate was 0.5mm / min, and each sample was tested 3 times. The average value was taken. The results are as follows:

[0088] Table 2

[0089]

[0090] As shown in Table 2, the Vickers hardness and flexural strength of the examples are significantly higher than those of the comparative examples. The composite doping elements B and Zr can refine the grains, forming dispersed second-phase particles that hinder dislocation movement, thereby improving hardness and strength.

[0091] Experiment 3: Sputtering performance test;

[0092] Referring to GB / T15860-2018, the target was mounted on a magnetron sputtering device, and sputtering tests were conducted under an argon atmosphere. The sputtering power was 300 W, the sputtering time was 60 min, the substrate temperature was 200℃, and the target-substrate distance was 8 cm. The sputtering rate was tested, and the surface roughness Ra of the deposited film was measured using an atomic force microscope. The film thickness uniformity was analyzed using a laser particle size analyzer (thickness variation coefficients at 5 test points were taken). The results are as follows:

[0093] Table 3

[0094]

[0095] As shown in Table 3, the embodiments exhibit higher sputtering rates, lower film roughness, and better thickness uniformity. High-density, high-compactness targets reduce particle splashing during sputtering, and composite doping optimizes the electrical and thermal conductivity of the target material, improving sputtering stability. Comparative Example 1, due to its low density and internal porosity, suffers from a decreased sputtering rate and poor film uniformity.

[0096] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high-purity tantalum rotating target, characterized in that, include: Main component: tantalum powder; Modification components: 0.001-0.005 wt% of composite doping elements are added; The composite doping elements are B and Zr mixed in a mass ratio of 1:2-3; The method for preparing the high-purity tantalum rotating target includes the following steps: S1. Raw material pretreatment: 4N grade tantalum powder was selected and reduced in stages under a hydrogen atmosphere. The molten salt system was a 1:1 mass ratio of NaCl-KCl, and the mass ratio of molten salt to tantalum powder was 2:

1. After reduction, the powder was acid-washed with 10% hydrochloric acid for 5-8 minutes, then washed with deionized water until neutral, and dried to constant weight. The staged reduction under hydrogen atmosphere included: Stage 1: 850℃, 0.5kPa hydrogen partial pressure, and holding for 4 hours; Stage 2: 950℃, 2kPa hydrogen partial pressure, and holding for 8 hours. S2. Composite doping: Pretreated tantalum powder is mixed with boron oxide-zirconium hydride dopant, first ultrasonically dispersed for 30 min, and then ball-milled for 3 h to obtain mixed powder; S3. Sintering and shaping: Vacuum hot pressing sintering is performed to obtain the green body; S4. Plastic processing: The billet is cold rolled with a deformation of 60-70%, and then annealed under vacuum at 1100-1200℃ and 0.0001Pa. Before cold rolling, a power gradient and amplitude gradient ultrasonic-assisted pretreatment is introduced for 30 minutes. The power is increased from 15kHz to 30kHz at a rate of 0.5kHz per minute, and the amplitude is increased from 30μm to 60μm at a rate of 1μm per minute, all simultaneously. The cold rolling die is preheated to 150-200℃ to reduce deformation resistance. Cold rolling is carried out in three stages of gradient deformation: the first stage has a deformation amount of 30% at a rate of 2mm / s, the middle stage has a deformation amount of 20% at a rate of 1.5mm / s, and the last stage has a deformation amount of 10-20% at a rate of 1mm / s. Between each stage, the stress-relief annealing is carried out under argon protection at 800℃, followed by isothermal holding for 1 hour and then rapid cooling to room temperature at a rate of 5℃ / min. After cold rolling, the surface is subjected to low-temperature plasma impact and ultrasonic-assisted nano-sizing treatment in sequence. Low-temperature plasma impact, argon atmosphere, 300W power for 10 minutes; ultrasonic-assisted surface nano-treatment, 20kHz ultrasonic and diamond micro powder grinding for 15 minutes, refine the surface grains to 100-200nm. S5. Finished product processing: After precision machining, the sputtering surface is mirror polished with a diamond grinding wheel to obtain a sputtering surface Ra≤0.03μm.

2. The high-purity tantalum rotating target according to claim 1, characterized in that, The target material density is ≥16.6 g / cm³. 3 Density ≥ 99.8%.

3. The high-purity tantalum rotating target according to claim 1, characterized in that, In step S1, after acid washing with hydrochloric acid, the sample is passivated with 0.1 mol / L HF solution for 10 min.

4. The high-purity tantalum rotating target according to claim 1, characterized in that, In step S2, the boron oxide-zirconium hydride dopant needs to be vacuum dried at 120°C for 4 hours before being added to remove adsorbed water.

5. The high-purity tantalum rotating target according to claim 1, characterized in that, In step S2, the ball milling is performed at a ball-to-material ratio of 12:1 and a rotation speed of 350 r / min.

6. The high-purity tantalum rotating target according to claim 1, characterized in that, In step S2, the frequency of the ultrasonic dispersion is 20 kHz.

7. The high-purity tantalum rotating target according to claim 1, characterized in that, In step S3, the vacuum degree of the vacuum sintering is 1-1.5 Pa, the sintering temperature is 1300-1800℃, the applied pressure is 40-46 MPa, and the time is 4-5 h.

8. The high-purity tantalum rotating target according to claim 1, characterized in that, In step S4, vacuum flattening annealing is performed under pressure of 5-8 MPa for 4-6 hours.

9. The high-purity tantalum rotating target according to claim 1, characterized in that, In step S5, after mirror polishing, plasma cleaning is performed with the following parameters: argon gas, power 500W, time 5min.

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