A wti alloy target and a method of manufacturing the same

Abstract

This invention provides a WTi alloy target and its preparation method, relating to the field of metallurgical technology. The preparation method includes the following steps: pretreating raw tungsten powder and raw titanium powder; ball milling and mixing the pretreated tungsten powder and titanium powder in a certain proportion; then subjecting the mixed powder to spark plasma sintering to obtain a WTi alloy ingot; vacuum annealing the WTi alloy ingot; and finally machining the vacuum annealed ingot to obtain the WTi alloy target. The plasma sintering adopts a three-stage heating method to reach the sintering temperature. The WTi alloy target obtained by this preparation method has high purity, high density, and uniform microstructure without segregation.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to a WTi alloy target and its preparation method. Background Technology

[0002] Tungsten-titanium alloy (W-Ti) has become an indispensable key functional material in fields such as semiconductor integrated circuits, flat panel displays, hard functional coatings, and new energy due to its high melting point, excellent high-temperature stability, good diffusion barrier properties, moderate resistivity, and excellent corrosion resistance. It is mainly used in the form of sputtering targets to prepare functional thin films through physical vapor deposition (PVD) processes, and is widely used in core structures such as metal interconnect barrier layers of semiconductor chips, gate electrodes of display panels, and wear-resistant protective layers of cutting tools.

[0003] Currently, the preparation of tungsten-titanium alloy targets is mainly based on powder metallurgy. Traditional processes include vacuum hot pressing sintering, cold isostatic pressing-vacuum sintering, and hot isostatic pressing (HIP). However, these processes generally have problems such as high sintering temperature (1200-1800℃), long holding time (several hours), easy coarsening of grains, difficulty in controlling oxygen content, and difficulty in densifying large-size blanks, which make it difficult to meet the needs of high-end applications.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a WTi alloy target and its preparation method. The WTi alloy target obtained by this preparation method has high purity, high density, and uniform microstructure without segregation.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a WTi alloy target, the method comprising the following steps: pretreating raw tungsten powder and raw titanium powder; ball milling and mixing the pretreated tungsten powder and titanium powder in a certain proportion; then subjecting the mixed powder to spark plasma sintering to obtain a WTi alloy ingot; vacuum annealing the WTi alloy ingot; and finally machining the vacuum annealed ingot to obtain the WTi alloy target. The plasma sintering process employs a three-stage heating method to raise the temperature to the sintering temperature. The three-stage heating method is as follows: First stage: from room temperature to 300℃, heating rate is 80-110℃ / min, pressure is 8-12MPa; Second stage: from 300℃ to 800℃, heating rate is 130-160℃ / min, pressure is 13-18MPa; Third stage: from 800℃ to 1200-1500℃, heating rate is 110-130℃ / min, pressure is 30-35MPa, holding for 15-25min, with a total vacuum ≤5×10⁻⁵. -3 Pa.

[0007] Furthermore, the pretreatment of the raw tungsten powder includes: vacuum baking the raw tungsten powder at a temperature of 300-400℃ for 1-2 hours.

[0008] Furthermore, the pretreatment of the raw titanium powder specifically involves placing the raw titanium powder in a hydrogen atmosphere for pre-reduction treatment at a temperature of 500-600℃ for 2-3 hours.

[0009] Furthermore, the pretreated tungsten powder and titanium powder are mixed in a high-energy ball mill at a ratio of 40-90 at% tungsten powder and 10-60 at% titanium powder, with a total atomic percentage of 100%.

[0010] Furthermore, the purity of the raw material tungsten powder is ≥99.95wt%, and the particle size is 325-500 mesh.

[0011] Furthermore, the purity of the raw material titanium powder is ≥99.95wt%, and the particle size is 325-500 mesh.

[0012] Furthermore, the ball milling and homogenization treatment is a wet ball milling and homogenization treatment. Preferably, the wet ball milling and homogenization treatment includes: adding anhydrous ethanol as a dispersant to the pretreated tungsten powder and titanium powder, purging the ball mill jar with argon gas for protection, the ball milling speed is 200-300 r / min, the ball milling time is 4-6 h, and the total mass ratio of tungsten powder and titanium powder to anhydrous ethanol is 10:1.

[0013] Furthermore, the vacuum annealing treatment is carried out at a temperature of 800-900℃, for a time of 1-2 hours, and with a vacuum level ≤5×10⁻⁶. -3 Pa.

[0014] Furthermore, the WTi alloy target has a relative density ≥99%, an oxygen content ≤300ppm, and a uniform microstructure distribution.

[0015] A second aspect of the present invention provides a WTi alloy target material prepared by the method of the first aspect, wherein the WTi alloy target material is composed of the following components in atomic percentage: W: 40-90%, Ti: 10-60%.

[0016] The WTi alloy target and its preparation method provided by this invention have the following advantages: (1) The present invention obtains WTi alloy target material with relative density ≥99.0%, oxygen content ≤300ppm and uniform structure in a wide range of Ti content from 10at% to 60at% by powder pretreatment + argon high-energy blending ball milling + multi-stage heating SPS sintering + vacuum annealing. (2) This invention adopts a three-stage gradient heating SPS sintering, which is different from the single-stage constant rate heating process. The low-temperature stage removes residual ethanol and adsorbed water vapor from the ball mill at low speed and low pressure, avoids powder splashing and fully removes oxygen-containing impurities. The medium-temperature stage increases the heating rate and pressure, accelerates the decomposition of the oxide layer on the surface of titanium powder, realizes the pre-diffusion of W and Ti powders, inhibits the local enrichment of titanium elements, and inhibits the formation of coarse titanium-rich phases in the high-titanium system from the source. The high-temperature stage lowers the heating rate and increases the pressure significantly, reduces the temperature difference between the inside and outside of the billet, reduces the sintering thermal stress, avoids the generation of microcracks, promotes the plastic rheological closure of pores of powder particles, and stably achieves high density, while taking into account the sintering production efficiency. It overcomes the defects of high oxygen content, severe titanium element segregation, microcracks in the billet, and insufficient density that are easily caused by using a single-stage uniform heating. The method of this invention is suitable for the preparation of WTi alloys with a wide ratio of titanium atomic percentage up to 60%.

[0017] (3) The vacuum annealing process after sintering, compared with the direct furnace cooling after sintering, can fully release the residual internal stress accumulated by the rapid sintering of SPS, and avoid edge chipping and microcracks during machining; the annealing process promotes the secondary uniform diffusion of W and Ti atoms, disperses the local titanium-rich agglomeration area, and further optimizes the uniformity of the structure; the high vacuum annealing environment throughout the process will not introduce additional oxygen impurities, and continuously maintains the low oxygen level of the target material, thereby improving the target material processing yield and the stability of sputtered film performance; (4) The WTi alloy target prepared by the present invention has low energy consumption, low cost and high yield. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 A process flow diagram for the preparation of WTi alloy targets provided by the present invention; Figure 2 This is a SEM image of the WTi alloy target provided in Embodiment 1 of the present invention; Figure 3 This is a SEM image of the WTi alloy target provided in Embodiment 2 of the present invention; Figure 4 This is a SEM image of the WTi alloy target provided in Embodiment 3 of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Those skilled in the art should understand that the embodiments described are merely illustrative of the invention and should not be considered as specific limitations thereof. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention. Process parameters not specifically specified in the following embodiments are generally performed under conventional conditions.

[0021] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0022] According to a first aspect of the present invention, the present invention provides a method for preparing a WTi alloy target, the method comprising the following steps: pretreating raw tungsten powder and raw titanium powder, ball milling and mixing the pretreated tungsten powder and titanium powder in a certain proportion, then subjecting the mixed powder to spark plasma sintering to obtain a WTi alloy ingot; vacuum annealing the WTi alloy ingot, and finally machining the vacuum annealed ingot to obtain a WTi alloy target; The plasma sintering process employs a three-stage heating method to raise the temperature to the sintering temperature. The three-stage heating method is as follows: First stage: from room temperature to 300℃, heating rate is 80-110℃ / min, pressure is 8-12MPa; Second stage: from 300℃ to 800℃, heating rate is 130-160℃ / min, pressure is 13-18MPa; Third stage: from 800℃ to 1200-1500℃, heating rate is 110-130℃ / min, pressure is 30-35MPa, holding for 15-25min, with a total vacuum ≤5×10⁻⁵. -3 Pa.

[0023] In this invention, the mixed powder of W powder and Ti powder, which has been ball-milled and homogenized, is loaded into a graphite mold and then placed in a spark plasma sintering equipment for sintering.

[0024] In this invention, the percentage of Ti atoms in the WTi alloy target can reach 60%, which is higher than the titanium content of traditional WTi alloy targets. This invention solves the problem of coarse and unevenly distributed titanium-rich phase caused by high titanium content by using three-stage gradient variable rate and variable pressure SPS sintering combined with vacuum annealing after sintering.

[0025] This invention employs a three-stage heating method to reach the sintering temperature. Compared to a continuous and stable heating rate, this method avoids defects such as powder splashing caused by rapid evaporation of ethanol and water vapor at low temperatures, insufficient impurity removal at low temperatures leading to high oxygen content, uneven decomposition of the titanium oxide layer at medium temperatures causing local enrichment of titanium elements, excessive temperature difference between the inside and outside of the billet at high temperatures resulting in thermal stress microcracks, and insufficient density due to difficulty in fully closing pores. This method achieves the following: stepwise removal of impurities to stabilize and control the oxygen content of the target material; staged pressure matching to promote W-Ti pre-diffusion and inhibit the formation of coarse titanium-rich phases; mitigation of sintering thermal stress to reduce billet cracking; and improvement of the overall density of the billet. It also achieves a fine and uniform microstructure with a wide proportion of high Ti atomic percentage of 10-60%. Vacuum annealing of WTi alloy ingots can solve the problems of residual sintering thermal stress in the billet after rapid SPS sintering and cooling, stress concentration leading to machining edge chipping and microcracks, rapid cooling freezing of local titanium-rich agglomerates, and poor target material microstructure stability. Its advantages are that high-vacuum, medium-temperature holding fully releases residual sintering internal stress, significantly improving the ingot machining yield; at the same time, it provides diffusion power for W and Ti atoms, breaking up the coarse, lumpy titanium-rich phases and further optimizing the microstructure uniformity; the full-vacuum environment does not introduce oxygen impurities, stably maintaining the low-oxygen, high-density advantages of the target material, and significantly improving the resistivity uniformity of subsequent sputtered thin films and the stability of the barrier layer.

[0026] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the pretreatment of the raw tungsten powder includes: vacuum baking the raw tungsten powder at a temperature of 300-400℃ (e.g., 320℃, 340℃, 360℃, 380℃) for 1-2 h (e.g., 1.2h, 1.4h, 1.6h, 1.8h). Vacuum baking of the raw tungsten powder can remove moisture and volatile impurities from the surface of the tungsten powder, and vacuum baking can be carried out in a vacuum oven.

[0027] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the pretreatment of the raw titanium powder specifically involves: placing the raw titanium powder in a hydrogen atmosphere for pre-reduction treatment at a temperature of 500-600℃ (e.g., 520℃, 540℃, 560℃, 580℃, 590℃) and holding it at that temperature for 2-3 hours (e.g., 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours). The pre-reduction of the titanium powder can remove adsorbed oxygen and oxide layer from its surface, and the pre-reduction step can be carried out in a tube furnace.

[0028] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the pretreated tungsten powder and titanium powder are mixed in a high-energy ball mill at a ratio of 40-90 at% (e.g., 50 at%, 60 at%, 70 at%, 80 at%) and 10-60 at% (e.g., 20 at%, 30 at%, 40 at%, 50 at%) of tungsten powder, with a total atomic percentage of 100%, for ball milling and mixing.

[0029] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the purity of the raw material tungsten powder is ≥99.95wt%, and the particle size is 325-500 mesh (e.g., 330 mesh, 350 mesh, 380 mesh, 400 mesh, 420 mesh, 440 mesh, 460 mesh, 480 mesh).

[0030] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the purity of the raw material titanium powder is ≥99.95wt% and the particle size is 325-500 mesh (e.g., 330 mesh, 350 mesh, 380 mesh, 400 mesh, 420 mesh, 440 mesh, 460 mesh, 480 mesh).

[0031] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the ball milling and homogenization treatment is a wet ball milling and homogenization treatment. Preferably, the wet ball milling and homogenization treatment includes: adding anhydrous ethanol as a dispersant to the pretreated tungsten powder and titanium powder, purging the ball milling jar with argon gas protection, ball milling speed of 200-300 r / min (e.g., 220 r / min, 240 r / min, 260 r / min, 280 r / min), ball milling time of 4-6 h (e.g., 4.5 h, 5 h, 5.5 h), and the mass ratio of the total mass of tungsten powder and titanium powder to the mass of anhydrous ethanol is 10:1.

[0032] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the vacuum annealing temperature is 800-900℃ (e.g., 820℃, 840℃, 860℃, 880℃), the vacuum annealing time is 1-2h (e.g., 1.2h, 1.4h, 1.6h, 1.8h), and the vacuum temperature is ≤5×10⁻⁶. -3 Pa. Vacuum annealing can be performed in a vacuum annealing furnace.

[0033] As an optional embodiment of the preparation method of the WTi alloy target of the present invention, the WTi alloy target has a relative density ≥99%, an oxygen content ≤300ppm, and a uniform microstructure distribution.

[0034] According to a second aspect of the present invention, the present invention provides a WTi alloy target prepared by the preparation method of the first aspect, wherein the WTi alloy target is composed of the following components in atomic percentage: W: 40-90% (e.g., 50%, 60%, 70%, 80%), Ti: 10-60% (e.g., 20%, 30%, 40%, 50%).

[0035] The present invention will now be described in further detail with reference to specific embodiments and comparative examples.

[0036] Example 1 1. Powder Pretreatment: Ti powder with a purity of 99.95 wt% and a particle size of 325 mesh and W powder with a purity of 99.95 wt% and a particle size of 325 mesh were selected. First, the Ti powder was placed in a hydrogen atmosphere tube furnace for pre-reduction treatment at a reduction temperature of 550℃ for 2.5 hours to remove adsorbed oxygen and oxide layer from the Ti powder surface. Simultaneously, the W powder was placed in a vacuum oven for vacuum baking at a temperature of 350℃ for 1.5 hours to remove surface moisture and volatile impurities.

[0037] 2. Powder mixing: The pretreated W powder and Ti powder were added into the high-energy ball mill jar at an atomic percentage ratio of 60%:40% (W: 60%, Ti: 40%). Anhydrous ethanol was added as a dispersant at a weight ratio of 10:1 between the total weight of W powder and Ti powder and the weight of anhydrous ethanol. The ball mill jar was purged with argon gas for protection. The ball mill speed was set to 250 r / min and the ball milling time was 5 h to achieve uniform mixing of W powder and Ti powder.

[0038] 3. Plasma Sintering: The mixed powder obtained in step 2 is loaded into a graphite mold and placed in a spark plasma sintering (SPS) apparatus for sintering. The first stage: room temperature to 300℃, heating rate 100℃ / min, pressure 10MPa; the second stage: 300℃ to 800℃, heating rate 150℃ / min, pressure 15MPa; the third stage: 800℃ to 1350℃, heating rate 120℃ / min, pressure 35MPa, holding for 20min, with a total vacuum ≤5×10⁻⁶ throughout. -3 Pa; 4. Vacuum annealing: The ingot obtained in step 3 is placed in a vacuum annealing furnace for vacuum annealing at 850℃ for 1.5 hours, with a vacuum level ≤5×10⁻⁶. -3 Pa.

[0039] 5. Machining: The ingot prepared in step 4 is machined and cleaned to obtain the finished WTi alloy target.

[0040] The WTi alloy target prepared in this embodiment has a relative density of 99.5%, an oxygen content of 270 ppm, and exhibits fine, uniformly distributed titanium-rich phases without coarse segregation. The SEM image of the WTi alloy target prepared in this embodiment is shown below. Figure 2 .

[0041] Example 2 1. Powder Pretreatment: Ti powder with a purity of 99.95 wt% and a particle size of 325 mesh and W powder with a purity of 99.95 wt% and a particle size of 325 mesh were selected. First, the Ti powder was placed in a hydrogen atmosphere tube furnace for pre-reduction treatment at a reduction temperature of 550℃ for 2.5 hours to remove adsorbed oxygen and oxide layer from the Ti powder surface. Simultaneously, the W powder was placed in a vacuum oven for vacuum baking at a temperature of 350℃ for 1.5 hours to remove surface moisture and volatile impurities.

[0042] 2. Powder mixing: The pretreated W powder and Ti powder were added into the high-energy ball mill jar at an atomic percentage ratio of 80%:20% (W: 80%, Ti: 20%). Anhydrous ethanol was added as a dispersant at a weight ratio of 10:1 between the total weight of W powder and Ti powder and the weight of anhydrous ethanol. The ball mill jar was purged with argon gas for protection. The ball mill speed was set to 200 r / min and the ball milling time was 6 h to achieve uniform mixing of W powder and Ti powder.

[0043] 3. Plasma Sintering: The mixed powder obtained in step 2 is loaded into a graphite mold and placed in a spark plasma sintering (SPS) apparatus for sintering. The first stage: room temperature to 300℃, heating rate 100℃ / min, pressure 10MPa; the second stage: 300℃ to 800℃, heating rate 150℃ / min, pressure 15MPa; the third stage: 800℃ to 1500℃, heating rate 120℃ / min, pressure 35MPa, holding for 20min, with a total vacuum ≤5×10⁻⁶ throughout. -3 Pa; 4. Vacuum annealing: The ingot obtained in step 3 is placed in a vacuum annealing furnace for vacuum annealing at 850℃ for 1.5 hours, with a vacuum level ≤5×10⁻⁶. -3 Pa.

[0044] 5. Machining: The ingot prepared in step 4 is machined and cleaned to obtain the finished WTi alloy target.

[0045] The WTi alloy target prepared in this embodiment has a relative density of 99.2%, an oxygen content of 290 ppm, fine titanium-rich phases without coarse segregation, and is dense and uniform. The SEM image of the WTi alloy target prepared in this embodiment is shown below. Figure 3 .

[0046] Example 3 1. Powder Pretreatment: Ti powder with a purity of 99.95 wt% and a particle size of 325 mesh and W powder with a purity of 99.95 wt% and a particle size of 325 mesh were selected. First, the Ti powder was placed in a hydrogen atmosphere tube furnace for pre-reduction treatment at a reduction temperature of 600℃ for 2.5 hours to remove adsorbed oxygen and oxide layer from the Ti powder surface. Simultaneously, the W powder was placed in a vacuum oven for vacuum baking at a temperature of 400℃ for 1 hour to remove surface moisture and volatile impurities.

[0047] 2. Powder mixing: The pretreated W powder and Ti powder were put into the high-energy ball mill jar at an atomic percentage ratio of 40%:60% (W: 40%, Ti: 60%). Anhydrous ethanol was added as a dispersant at a weight ratio of 10:1 between the total weight of W powder and Ti powder and the weight of anhydrous ethanol. The ball mill jar was purged with argon gas for protection. The ball mill speed was set to 300 r / min and the ball milling time was 4 h to achieve uniform mixing of W powder and Ti powder.

[0048] 3. Plasma Sintering: The mixed powder obtained in step two is loaded into a graphite mold and placed in a spark plasma sintering (SPS) apparatus for sintering. The first stage: room temperature to 300℃, heating rate 100℃ / min, pressure 10MPa; the second stage: 300℃ to 800℃, heating rate 150℃ / min, pressure 15MPa; the third stage: 800℃ to 1350℃, heating rate 120℃ / min, pressure 35MPa, holding for 20min, with a total vacuum ≤5×10⁻⁶ throughout. -3 Pa; 4. Vacuum annealing: The ingot obtained in step three is placed in a vacuum annealing furnace for vacuum annealing at 850℃ for 1.5 hours, with a vacuum level ≤5×10⁻⁶. -3 Pa.

[0049] 5. Machining: The ingot prepared in step four is machined and cleaned to obtain the finished WTi alloy target.

[0050] The WTi alloy target prepared in this embodiment has a relative density of 99.5%, an oxygen content of 260 ppm, fine and uniformly distributed titanium-rich phases without coarse segregation, and a dense and uniform microstructure despite an ultra-high titanium ratio. The SEM image of the WTi alloy target prepared in this embodiment is shown below. Figure 4 .

[0051] Comparative Example 1 1. Powder Pretreatment: Ti powder with a purity of 99.95 wt% and a particle size of 325 mesh and W powder with a purity of 99.95 wt% and a particle size of 325 mesh were selected. First, the Ti powder was placed in a hydrogen atmosphere tube furnace for pre-reduction treatment at a reduction temperature of 550℃ for 2.5 hours to remove adsorbed oxygen and oxide layer from the Ti powder surface. Simultaneously, the W powder was placed in a vacuum oven for vacuum baking at a temperature of 350℃ for 1.5 hours to remove surface moisture and volatile impurities.

[0052] 2. Powder mixing: The pretreated W powder and Ti powder were added into the high-energy ball mill jar at an atomic percentage ratio of 60%:40% (W: 60%, Ti: 40%). Anhydrous ethanol was added as a dispersant at a weight ratio of 10:1 between the total weight of W powder and Ti powder and the weight of anhydrous ethanol. The ball mill jar was purged with argon gas for protection. The ball mill speed was set to 250 r / min and the ball milling time was 5 h to achieve uniform mixing of W powder and Ti powder.

[0053] 3. Vacuum hot pressing sintering: The mixed powder is loaded into a graphite mold and placed in a vacuum hot pressing sintering furnace. The sintering temperature is 1350℃, the pressure is 35MPa, and the holding time is 60min. The vacuum is maintained at ≤5×10⁻⁶ throughout the process. -3 Pa.

[0054] 4. Machining: Machining the ingot from step 3 and cleaning it to obtain the finished WTi alloy target.

[0055] The WTi alloy target prepared in this comparative example has a relative density of about 98% and an oxygen content of 380 ppm.

[0056] Compared with the alloy target material prepared in Example 1, even with the same sintering temperature and extended holding and pressure time, the target material is still not dense enough, and the titanium-rich phase is coarse, locally aggregated, and has obvious coarse segregation.

[0057] Comparative Example 2 1. Powder Pretreatment: Ti powder with a purity of 99.95 wt% and a particle size of 325 mesh and W powder with a purity of 99.95 wt% and a particle size of 325 mesh were selected. First, the Ti powder was placed in a hydrogen atmosphere tube furnace for pre-reduction treatment at a reduction temperature of 550℃ for 2.5 hours to remove adsorbed oxygen and oxide layer from the Ti powder surface. Simultaneously, the W powder was placed in a vacuum oven for vacuum baking at a temperature of 350℃ for 1.5 hours to remove surface moisture and volatile impurities. 2. Powder mixing: The pretreated W powder and Ti powder were put into the high-energy ball mill jar at an atomic percentage ratio of 60%:40% (W:60%, Ti:40%). Anhydrous ethanol was added as a dispersant at a ratio of 10:1 between the total weight of W powder and Ti powder and the weight of anhydrous ethanol. The ball mill jar was purged with argon gas for protection. The ball mill speed was set to 250 r / min and the ball milling time was 5 h to achieve uniform mixing of W powder and Ti powder. 3. Vacuum sintering: The powder obtained in step 2 is pressed into a green blank by cold isostatic pressing (200MPa), and then placed in a vacuum tube furnace for pressureless sintering at a temperature of 1350℃ and a holding time of 2h. 4. Machining: Machining the ingot from step 3 and cleaning it to obtain the finished WTi alloy target.

[0058] The WTi alloy target prepared in this comparative example has a relative density of about 98% and an oxygen content of 400 ppm.

[0059] Compared with the technique used to prepare the alloy target material in Example 1, the sintering time is longer and the density is lower.

[0060] Comparative Example 3 The only difference between this comparative example and Example 1 is that the plasma sintering heating process uses a heating rate of 100℃ / min to heat up to 1350℃ in one step, while the pressure is always maintained at 10MPa.

[0061] Results: The single heating rate throughout the process could not meet the process requirements of each stage: low-temperature impurity removal, medium-temperature pre-diffusion, and high-temperature densification. In the low-temperature range, ethanol and adsorbed water vapor evaporated rapidly, resulting in insufficient removal of oxygen-containing impurities and an oxygen content of 345 ppm in the finished product. In the medium-temperature stage, the oxide layer on the surface of titanium powder decomposed unevenly, W and Ti powder pre-diffusion was insufficient, local overheating of the powder occurred, titanium elements showed significant segregation, and the titanium-rich phase was coarse and locally aggregated. In the high-temperature stage, the temperature difference between the inside and outside of the billet was large, plastic rheology was insufficient, a small number of interconnected micropores existed inside the billet, the relative density was only 97.1%, and the oxygen content was 345 ppm. The overall microstructure was poorly uniform, making it difficult to meet the requirements for use as a high-end semiconductor sputtering target.

[0062] Comparative Example 4 The only difference between this comparative example and Example 1 is that the plasma sintering heating process uses a heating rate of 120℃ / min to heat up to 1350℃ in one step, while the pressure is always maintained at 35MPa.

[0063] Results: Due to the lack of segmented speed and pressure regulation throughout the process, the low-temperature impurity removal effect was insufficient, and the oxygen content of the target material was 332 ppm; the pre-diffusion of W and Ti atoms at the medium temperature was insufficient, and there was still local enrichment of titanium, with the size of the titanium-rich phase being significantly larger; the high-temperature range lacked gradient pressure to assist pore closure, and the billet density was only 97.8%, with the composition and microstructure uniformity being significantly inferior to the three-stage heating process of this invention.

[0064] Comparative Example 5 The only difference between this comparative example and Example 1 is that the plasma sintering heating process uses a heating rate of 150℃ / min to heat up to 1350℃ in one step, while the pressure is always maintained at 15MPa.

[0065] Results: Due to the excessively rapid heating rate throughout the process, a huge temperature gradient was formed inside the billet, resulting in highly concentrated sintering thermal stress and visible microcracks at the edges of the billet. The low-temperature powder volatilized violently, and impurities were trapped inside the billet, with an oxygen content as high as 360 ppm. The titanium element melted and agglomerated rapidly upon heating, and the titanium-rich phase was severely coarsened, forming continuous titanium-rich segregation regions with significant compositional segregation. The final relative density was only 96.5%, and the product suffered from both cracking and compositional segregation defects, making it completely unsuitable for the production requirements of high-Ti content WTi sputtering targets and failing to meet the requirements of high-end applications.

[0066] Comparative Example 6 The only difference between this comparative example and Example 1 is that, after plasma sintering, vacuum annealing was not performed; instead, the plasma was cooled in the furnace.

[0067] Results: The ingot contained significant residual sintering internal stress, and the titanium-rich phase had irregular morphology and decreased distribution uniformity; it was prone to edge chipping and microcracks during machining; the oxygen content was 275 ppm and the relative density was 99.4%, and the structural stability and processing performance were weaker than the scheme with vacuum annealing.

[0068] Comparative Example 7 1. Powder Pretreatment: Ti powder with a purity of 99.95 wt% and a particle size of 325 mesh and W powder with a purity of 99.95 wt% and a particle size of 325 mesh were selected. First, the Ti powder was placed in a hydrogen atmosphere tube furnace for pre-reduction treatment at a reduction temperature of 550℃ for 2.5 hours to remove adsorbed oxygen and oxide layer from the Ti powder surface. Simultaneously, the W powder was placed in a vacuum oven for vacuum baking at a temperature of 350℃ for 1.5 hours to remove surface moisture and volatile impurities.

[0069] 2. Powder mixing: The pretreated W powder and Ti powder were added into the high-energy ball mill jar at an atomic percentage ratio of 60%:40% (W: 60%, Ti: 40%). Anhydrous ethanol was added as a dispersant at a weight ratio of 10:1 between the total weight of W powder and Ti powder and the weight of anhydrous ethanol. The ball mill jar was purged with argon gas for protection. The ball mill speed was set to 250 r / min and the ball milling time was 5 h to achieve uniform mixing of W powder and Ti powder.

[0070] 3. Vacuum hot pressing sintering: The mixed powder is loaded into a graphite mold and placed in a vacuum hot pressing sintering furnace. The sintering temperature is 1400℃, the pressure is 35MPa, and the holding time is 60min. The vacuum is maintained at ≤5×10⁻⁶ throughout the process. -3 Pa.

[0071] 4. Machining: Machining the ingot from step 3 and cleaning it to obtain the finished WTi alloy target.

[0072] As a result, the relative density of the target material was about 98.1%, and the oxygen content was 355 ppm; there were a few micro-closed pores inside the billet, and slight edge chipping occasionally occurred during machining.

[0073] The performance testing methods refer to the following standards: The standard for testing the relative density of WTi alloy sputtering targets is: GB / T 3850-2015 Method for Determination of Density of Dense Sintered Metallic Materials and Hard Alloys, where relative density = (actual measured density / theoretical density). 100%.

[0074] The standard for oxygen content testing is GB / T 14265-2017 General Rules for the Determination of Hydrogen, Oxygen, Nitrogen, Carbon and Sulfur Content in Metallic Materials.

[0075] The standard for testing the density of target materials is GB / T 13298-2015 "Metallic Microstructure Examination Method".

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of producing a WTi alloy target material, characterized by, The preparation method includes the following steps: pre-treating raw tungsten powder and raw titanium powder, ball milling and mixing the pre-treated tungsten powder and titanium powder in proportion, then performing spark plasma sintering on the mixed powder to obtain WTi alloy ingot; vacuum annealing the WTi alloy ingot, and finally machining the vacuum annealed ingot to obtain WTi alloy target material. The plasma sintering process employs a three-stage heating method to raise the temperature to the sintering temperature. The three-stage heating method is as follows: First stage: room temperature to 300℃, heating rate is 80-110℃ / min, pressure is 8-12MPa; Second stage: 300℃ to 800℃, heating rate of 130-160℃ / min, pressure of 13-18MPa; Third segment: 800-1200-1500℃, heating rate 110-130℃ / min, pressure 30-35MPa, holding time 15-25min, vacuum ≤5×10 -3 Pa throughout the whole process.

2. The method of claim 1, wherein the WTi alloy target is prepared by a process comprising: The pretreatment of the raw tungsten powder includes: vacuum baking the raw tungsten powder at a temperature of 300-400℃ for 1-2 hours.

3. The method of claim 1, wherein the WTi alloy target is prepared by a process comprising: The pretreatment of the raw titanium powder specifically involves placing the raw titanium powder in a hydrogen atmosphere for pre-reduction treatment at a temperature of 500-600℃ for 2-3 hours.

4. The method for preparing the WTi alloy target according to claim 1, characterized in that, The pretreated tungsten powder and titanium powder are mixed in a high-energy ball mill at a ratio of 40-90 at% tungsten powder and 10-60 at% titanium powder, with a total atomic percentage of 100%.

5. The method of claim 1, wherein the WTi alloy target is prepared by a process comprising: The purity of the tungsten powder used in the raw material is ≥99.95wt%, and the particle size is 325-500 mesh.

6. The method of claim 1, wherein the WTi alloy target is prepared by a process comprising: The purity of the raw material titanium powder is ≥99.95wt%, and the particle size is 325-500 mesh.

7. The method of claim 1, wherein the WTi alloy target is prepared by a process comprising: The ball milling and homogenization treatment is a wet ball milling and homogenization treatment. Preferably, the wet ball milling and homogenization treatment includes: adding anhydrous ethanol as a dispersant to the pretreated tungsten powder and titanium powder, purging the ball mill jar with argon gas for protection, the ball milling speed is 200-300 r / min, the ball milling time is 4-6 h, and the total mass ratio of tungsten powder and titanium powder to anhydrous ethanol is 10:

1.

8. The method of claim 1, wherein the WTi alloy target is prepared by a process comprising: The vacuum annealing process is carried out at a temperature of 800-900℃ for 1-2 hours, with a vacuum level ≤5×10⁻⁶. -3 Pa.

9. The method of claim 1, wherein the WTi alloy target is prepared by a process comprising: The WTi alloy target has a relative density of ≥99%, an oxygen content of ≤300ppm, and a uniform microstructure.

10. A WTi alloy target material prepared by the production method according to any one of claims 1 to 9, characterized in that, The WTi alloy target material is composed of the following components by atomic percentage: W: 40-90%, Ti: 10-60%.

Images