Large-size molybdenum-titanium alloy target material and preparation method thereof

Abstract

This invention discloses a large-size molybdenum-titanium alloy target and its preparation method. The preparation method includes the following steps: S1, selecting raw materials molybdenum powder and titanium powder; S2, granulating the molybdenum powder under inert gas protection to prepare granulated molybdenum powder, wherein the particle size and tap density of the granulated molybdenum powder are matched with those of the titanium powder; S3, mixing the granulated molybdenum powder and titanium powder in a certain proportion under inert gas protection; S4, degassing the mixed powder; S5, hot isostatic pressing to form an ingot; S6, vacuum heat treatment of the ingot to obtain the large-size molybdenum-titanium alloy target. By adding the granulation and forming process of molybdenum powder, the morphology of the raw materials is controlled, effectively suppressing the tendency of the mixed powder to separate in subsequent processing. This method significantly improves the compositional uniformity and batch stability of the molybdenum-titanium alloy target, avoids product defects and scrap due to separation, thereby reducing production costs and improving product qualification rate.

Description

Technical Field

[0001] This invention relates to the field of alloy target technology, specifically to a large-size molybdenum-titanium alloy target and its preparation method. Background Technology

[0002] Molybdenum-titanium alloy (MoTi) sputtering targets are widely used in advanced thin-film deposition technologies due to their high melting point, high strength, excellent thermal stability, and electrical conductivity. In the semiconductor field, as a key diffusion barrier layer material in copper interconnect processes, it effectively prevents copper atoms from diffusing into the silicon substrate, thereby improving chip performance and reliability. In the flat panel display field, it is commonly used as an electrode or wiring material, suitable for manufacturing high-precision, high-reliability microelectronic interconnect structures.

[0003] Currently, MoTi alloy sputtering targets are mainly sintered using hot isostatic pressing (HIP). As display panel sizes continue to increase, the size of MoTi sputtering targets is also increasing accordingly, with single targets reaching 3-4 meters in length. The amount of raw material powder required for a single preparation can reach several tons. In traditional large-size MoTi alloy sputtering powder metallurgy processes, molybdenum powder and titanium powder have inherent differences in physical properties; molybdenum's theoretical density (10.2 g / cm³) is much higher than titanium's (4.5 g / cm³). However, the actual raw material powder used is often characterized by extremely fine molybdenum powder with a large specific surface area and poor flowability, while titanium powder has relatively coarse particles and irregular morphology. This difference in raw material state, resulting from mainstream powder preparation processes (molybdenum powder is often obtained through reduction methods, resulting in fine particles; titanium powder is often obtained through hydrogenation-dehydrogenation methods, resulting in relatively coarse particles), is a common situation in the industry.

[0004] This combination of fine-grained high-density material powder and coarse-grained low-density material powder results in a significant difference in tap density between molybdenum powder and titanium powder. Actual measurements show that the tap density of the original molybdenum powder is approximately 1.8-2.2 g / cm³, while that of the original titanium powder is approximately 2.0-2.5 g / cm³. Although the absolute difference may seem small, due to the extremely fine particle size, large specific surface area, and poor flowability of molybdenum powder, a significant "dynamic separation" effect occurs during dynamic mixing and transport, influenced by gravity and vibration: the low-density, coarse-grained titanium powder tends to float or migrate, while the high-density, small-grained molybdenum powder tends to settle.

[0005] This stratification phenomenon, caused by the difference in tap density and particle size, is the fundamental physical reason for the compositional segregation, abnormal performance, and even the scrapping of the entire batch of sintered targets, which seriously affects the uniformity of large-size (length greater than 2700mm) MoTi targets. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention proposes a method for preparing large-size molybdenum-titanium alloy targets, comprising the following steps: S1. Select raw materials: molybdenum powder and titanium powder; S2. Under inert gas protection, molybdenum powder is granulated using a granulation process to prepare granulated molybdenum powder. The particle size and tap density of the granulated molybdenum powder are matched with those of the titanium powder. Matching means that the particle size range of the granulated molybdenum powder and the particle size range of the titanium powder overlap, or at least partially overlap; the tap density range of the granulated molybdenum powder and the tap density range of the titanium powder overlap, or at least partially overlap.

[0007] S3. Under the protection of inert gas, granulated molybdenum powder and titanium powder are mixed in proportion. S4. Degas the mixed powder; S5. Sintered into ingots by hot isostatic pressing; S6. Vacuum heat treatment is performed on the ingot to obtain a large-size molybdenum-titanium alloy target.

[0008] Changes in powder morphology are the main factor affecting tap density. Step S2 involves granulating the molybdenum powder to increase particle size and improve structural density, thereby increasing tap density. Ungranulated raw Mo powder has a fine particle size of 3-5 μm, poor flowability, and is prone to agglomeration. After granulation, the particles become short columnar or spherical, increasing in size to 20-100 μm, and the porosity between powder particles decreases. By adding a granulation process to control the raw material morphology, the tendency of mixed powders to stratify in subsequent processing is effectively suppressed. This method significantly improves product composition uniformity and batch stability, avoids product defects and scrap due to stratification, thereby reducing production costs and increasing product yield.

[0009] By subjecting the highly uniform mixed powder after granulation to degassing, hot isostatic pressing, and vacuum heat treatment under a strictly inert atmosphere, the dual stability of composition and structure is ensured, achieving high reproducibility and high-quality output throughout the entire process. This has resulted in a complete, stable, and innovative process specifically designed for the preparation of large-size, highly uniform MoTi alloy targets.

[0010] Furthermore, in S1, the purity of molybdenum powder is ≥99.95%, the particle size of molybdenum powder is 3~5μm, and the tap density of molybdenum powder is 1.8~2.2 g / cm³; the purity of titanium powder is ≥99.9%, the tap density of titanium powder is 2.0 - 2.5 g / cm³, and the D50 of titanium powder is 20 - 100μm.

[0011] Furthermore, in S2, the tap density of the granulated molybdenum powder is 2.2~2.8 g / cm³, and the D50 of the granulated molybdenum powder is 20~100μm. Granulation technology from the powder metallurgy field is creatively applied to solve the mixing uniformity problem of bimetallic alloy powder systems with high density differences. By processing fine Mo powder into granulated particles with larger particle sizes and higher tap densities, its tap density is increased from the original 1.8-2.2 g / cm³ to 2.2-2.8 g / cm³, an increase of approximately 25%. This allows its tap density range to fully overlap with that of titanium powder, and brings its particle size into the same order of magnitude as Ti powder. This reduces the density difference between Mo and titanium powder, decreases the differences in their physical properties, and fundamentally suppresses the tendency for separation under vibration and gravity.

[0012] Furthermore, in S2, the D50 particle size of the granulated molybdenum powder is 50-80 μm. By precisely controlling the D50 of the granulated molybdenum powder, the physical compatibility of the powder system is improved, fundamentally suppressing the tendency to separate under vibration and gravity.

[0013] Furthermore, in S2, the granulation process is selected from any one of extrusion granulation, spray granulation, and rolling granulation, and the extrusion granulation process is either dry extrusion granulation or wet extrusion granulation.

[0014] Furthermore, the extrusion pressure in the extrusion granulation process is 5 to 10 MPa.

[0015] Furthermore, the extrusion die material is selected from any one of cemented carbide, ceramic material, or die steel with a ceramicized surface. The die material is chosen to be a high-hardness, low-contamination material to avoid introducing metallic impurities that could contaminate the prepared molybdenum-titanium alloy target, leading to a decrease in purity and an increase in the target's resistivity. The extrusion die is either an extrusion roller that contacts the molybdenum powder in a dry extrusion process, or an extrusion screw that contacts the molybdenum powder in a wet extrusion process.

[0016] Furthermore, in the wet extrusion granulation process, the binder is selected from one or more of polyethylene glycol PEG-20000, PVA 1788 type polyvinyl alcohol, and paraffin wax.

[0017] Furthermore, the extrusion pressure in the extrusion granulation process is 5-10 MPa; by controlling the range of extrusion pressure, the powder particles are densified. Insufficient pressure results in loose particles with low densification; excessive pressure results in overly hard particles, which are difficult to pass through the subsequent die openings. During the process, it is essential to maintain stable equipment pressure and uniform pressing speed.

[0018] Furthermore, during the extrusion process, coarse particles with a diameter of less than 5 mm are first prepared, and then intermediate particles with a diameter of less than 1 mm are further prepared. Then, the particles are first sieved using a 100-mesh sieve to remove large-sized particles, and then sieved using a 150-mesh sieve. The powder that passes through the sieve is the target powder.

[0019] Furthermore, the wet extrusion granulation process includes the steps of feeding, mixing, aging, extrusion, pelleting, transfer, drying, cooling, crushing, and sieving. During the mixing process, a binder is added to the molybdenum powder. The binder is selected from one or more of polyethylene glycol, polyvinyl alcohol, and paraffin wax; wherein the polyethylene glycol is polyethylene glycol PEG-20000; and the polyvinyl alcohol is PVA 1788 type polyvinyl alcohol with a degree of polymerization of 1600-1800 and a degree of alcoholysis of 87%-89%. During the extrusion process, the screw extrusion pressure ranges from 5 to 10 MPa, extruding molybdenum powder into strips less than 5 mm in diameter. During the drying process, the temperature is increased in stages, with a drying temperature of 60~100℃; During the crushing process, the molybdenum powder particles are crushed into intermediate particles of less than 1 mm.

[0020] Furthermore, the dry extrusion granulation process includes feeding, extrusion, coarse crushing, fine granulation, and screening; During the extrusion process, the extrusion pressure is 5~10MPa, and the extruded powder appears as blocks or flakes; During the coarse crushing process, the lumpy or flaky material formed by compression is crushed into coarse particles with a diameter of less than 5 mm. During the finishing process, the coarse particles are further crushed into intermediate particles with a diameter of less than 1 mm.

[0021] A large-size molybdenum-titanium alloy target with a Mo / Ti atomic ratio standard deviation ≤1at.

[0022] Furthermore, the molybdenum-titanium alloy target material has a purity of ≥99.97%; O content <750ppm; C content <30ppm; Fe content <100ppm; and resistivity ≤42μΩ·cm.

[0023] The beneficial effects of this invention are: 1) Technological Solution Innovation: In the traditional powder metallurgy process for large-size MoTi alloy targets (single length can reach 3~4 meters), due to the difference in density and physical properties between Mo powder and Ti powder, up to several tons of Mo powder and Ti powder are easily affected by gravity and vibration during mixing, transportation and processing, resulting in component stratification, ultimately leading to microstructure segregation, abnormal performance and even scrapping of the entire batch of target products. This invention introduces the key step of "molybdenum powder granulation" in the raw material pretreatment stage, creatively applying the granulation technology in the field of powder metallurgy to solve the problem of mixing uniformity of bimetallic alloy powder systems with high density difference. By granulating fine Mo powder into larger particles with higher tap density, its tap density was increased from the original 1.8-2.2 g / cm³ to 2.2-2.8 g / cm³, an increase of approximately 25%. This allowed its tap density range to fully overlap with that of titanium powder, and brought its particle size to the same order of magnitude as Ti powder. This reduced the density difference between Mo and titanium powder, decreased the differences in their physical properties, and fundamentally suppressed the tendency to separate under vibration and gravity. This fundamentally improved the physical compatibility of the powder system, resulting in a highly uniform composition distribution in the prepared MoTi alloy ingot (Mo / Ti atomic ratio standard deviation < 1 at%).

[0024] 2) Innovation in problem approach: In response to the problem of poor uniformity of large-size MoTi targets, this invention does not optimize the subsequent mixing and sintering process parameters in a conventional way, but intervenes at the root cause of the mismatch in the physical morphology of the raw materials, and solves the systemic stratification problem by changing the physical morphology of the single component (Mo powder).

[0025] 3) Innovation in process integration: By degassing, hot isostatic pressing and vacuum heat treatment of the highly uniform mixed powder after granulation under strict inert atmosphere protection, the dual stability of composition and structure is ensured, and the high reproducibility and high quality output of the entire process are achieved. This forms a complete, stable and innovative process flow specifically for the preparation of large-size, highly uniform MoTi alloy targets.

[0026] 4) Technical Effects: The prepared large-size molybdenum-titanium alloy target significantly reduced the bulk resistivity of the target (≤42μΩ·cm), and fundamentally improved the compositional uniformity (standard deviation <1at%) and purity (≥99.97%), laying an indispensable material foundation for subsequent sputtering preparation of high-performance thin films. Furthermore, multiple parallel experiments demonstrated that the process is stable, the granulated powder exhibits excellent flowability, easier control of compositional uniformity, and increased powder filling rate, thereby enhancing the reproducibility and stability of the entire process, achieving a 100% batch qualification rate. Attached Figure Description

[0027] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a metallographic image of the molybdenum-titanium alloy target material prepared in Example 1 of the present invention. Detailed Implementation

[0030] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0031] Unless otherwise shown or indicated in the operational embodiments, all figures used to represent the amounts, physicochemical properties, etc., of ingredients in the specification and claims are to be understood to be adjusted by the term "about" in all cases. Therefore, unless stated to the contrary, the numerical parameters listed in the foregoing specification and appended claims are approximations, and those skilled in the art can appropriately modify these approximations to obtain the desired characteristics by utilizing the teachings disclosed herein. The use of numerical ranges indicated by endpoints includes all numbers within that range and any range within that range; for example, 1 to 5 includes 1, 1.1, 1.3, 1.5, 2, 2.75, 3, 3.80, 4, and 5, etc.

[0032] As display panel sizes continue to increase, the size of MoTi targets also increases accordingly, with single targets reaching 3-4 meters in length, forming large-size MoTi targets. To prepare large-size MoTi targets, the raw material powder required for a single preparation can reach several tons. In traditional powder metallurgy processes for large-size MoTi alloy targets, molybdenum powder and titanium powder have inherent differences in physical properties; molybdenum's theoretical density (10.2 g / cm³) is much higher than titanium's (4.5 g / cm³). The actual raw material powder used is often characterized by extremely fine molybdenum powder with a large specific surface area and poor flowability, while titanium powder has a relatively coarse particle size and irregular morphology. When the volume of molybdenum and titanium powder is relatively large, a significant "dynamic separation" effect occurs during dynamic mixing and transport due to gravity and vibration: low-density, coarse-grained titanium powder tends to float or migrate, while high-density, small-grained molybdenum powder tends to settle, resulting in poor uniformity of the prepared large-size MoTi targets.

[0033] To improve the compositional uniformity of MoTi targets, traditional methods for preparing large-size molybdenum-titanium alloy targets often employ CIP (cold isostatic pressing) for mixed powder preforming. However, this method requires multiple batches of CIP billets to be prepared, and then each billet is machined and placed into a HIP (hot isostatic pressing) casing for sintering. This process is cumbersome and significantly increases time and labor costs.

[0034] This invention provides a method for preparing large-size molybdenum-titanium alloy targets. Addressing the vibration stratification problem caused by the aforementioned differences in particle size and tap density, the method starts from the root cause of the raw material's physical morphology. By granulating molybdenum powder with specific parameters, the physical morphology of the raw material is changed, reducing the particle size and tap density differences between it and titanium powder, and fundamentally suppressing the separation tendency of the mixed powder system during dynamic processes.

[0035] A method for preparing a large-size molybdenum-titanium alloy target material specifically includes the following steps: S1. Select raw materials for molybdenum powder and titanium powder; The purity of the molybdenum powder raw material is ≥99.95%, the particle size of the molybdenum powder raw material is 3~5μm, the purity of the titanium powder is ≥99.9%, the tap density of the titanium powder is 2.0 - 2.5 g / cm³, and the D50 of the titanium powder is 20 - 100μm.

[0036] S2. Under the protection of inert gas, molybdenum powder is granulated through a granulation process to prepare granulated molybdenum powder. The particle size and tap density of the granulated molybdenum powder are matched with those of the titanium powder. The extrusion granulation process can be either dry extrusion granulation or wet extrusion granulation.

[0037] The dry extrusion granulation process specifically includes the following steps: [Unit 1: Feeding - Extrusion - Coarse Crushing - Fine Pelletizing] ① Feeding: First, add the raw Mo powder into the feed tank of the parallel double-roller extrusion granulator. After feeding, immediately seal the feed port and all valves connecting the equipment to the outside world to ensure the system is in a closed state.

[0038] ② Atmosphere Replacement: After the system is sealed, start the vacuum pump to evacuate the system. Then, close the vacuum pump and vacuum valve. Subsequently, slowly introduce an inert gas (such as argon or nitrogen) into the system. When the system pressure approaches atmospheric pressure, open the exhaust valve to remove residual air. Repeat the above "vacuuming-gas filling" cycle 1-2 times to reduce the oxygen content in the system to below 300 ppm, and monitor it in real time. Finally, a stable inert gas protective atmosphere is formed in the system to ensure that the molybdenum powder does not oxidize during subsequent processes.

[0039] ③ Extrusion: Rotate the feed valve to allow the material to fall into the equipment, where it is mechanically extruded and shaped by the extrusion rollers. The hydraulic system controls the inter-roller pressure within the range of 5~10MPa. The extrusion die is made of hard alloy or ceramic. The extruded powder appears as blocks or flakes.

[0040] ④ Coarse crushing: The lumpy or flaky material formed by extrusion enters the rotary auger crushing unit, where it is crushed by the rotary auger into smaller particles (auger speed is 100~200 rpm). The particles then pass through a 5mm diameter extrusion screen below the rotary auger to obtain coarse particles with a diameter of less than 5mm. ⑤ Fine Particles: The coarse particles are further crushed by the rotating reamer below (the reamer speed is 150~300rpm). (The purpose of this step is to further crush the coarse particles so that they can pass smoothly through the 1mm extrusion screen below and avoid screen blockage.) The particles are then passed through the 1mm diameter extrusion screen below the rotating reamer to obtain intermediate particles with a diameter of less than 1mm.

[0041] The process combines coarse crushing with fine granulation to ensure uniform particle size while generating an appropriate amount of fine powder through crushing, thus achieving a reasonable particle size match and improving the overall tap density of molybdenum powder.

[0042] Unit Two: Screening ⑥ Screening: Add intermediate particles with a diameter of 1mm or less into the sealed screening chamber. After closing the chamber lid, independently evacuate and purge the screening chamber with inert gas to reduce the oxygen content in the system to below 300ppm, and monitor in real time. Then, first screen with a 100-mesh (approximately 150μm aperture) screen to remove large particles. Next, screen with a 150-mesh (approximately 106μm aperture) screen; the powder passing through the screen is the target powder and is collected at the discharge port (protected by a nitrogen curtain). A small amount of coarse particles that do not pass through the screen are collected and carried into the granulation tank with the next batch of material for further extrusion and granulation, achieving recycling.

[0043] Through a two-stage sieving process of 100 mesh and 150 mesh, fine particles with D50 falling in the range of 50–80 μm (i.e., undersize particles ≤106 μm) are accurately separated from this range as the target product, while coarser particles of 106–150 μm are screened out and returned to the granulation process for reprocessing.

[0044] (2) Wet extrusion granulation process: [Unit 1: Feeding - Mixing - Aging - Extrusion - Pelletizing] (at room temperature) ① Feeding: Add a certain weight of raw Mo powder (the amount added does not exceed the working volume of the mixing silo) into the mixing silo, and close the silo cover and all system valves connected to the outside.

[0045] ② Atmosphere Replacement: Start the vacuum pump to evacuate the system. Then, turn off the vacuum pump and vacuum valve, and slowly introduce an inert gas (such as argon or nitrogen) into the system. When the system pressure approaches atmospheric pressure, open the exhaust valve to remove any remaining air. Repeat the above "vacuuming-gas filling" cycle 1-2 times to reduce the oxygen content in the system to below 300 ppm, and monitor it in real time.

[0046] ③ Mixing: Turn on the stirring device in the mixing hopper and set the stirring speed to 300~400 rpm to make the powder fluidized. Then, turn on the binder nozzle and slowly and evenly spray in the binder (the binder is a thermally decomposable organic binder, such as PEG, paraffin, etc.) until the powder reaches the wetness level where it can be formed into a ball by hand and easily crumbled when squeezed.

[0047] ④Aging: After mixing, the wet material is sealed and left to stand for 10-60 minutes (depending on the penetration of the binder) to avoid instability in the subsequent extrusion process due to uneven distribution of moisture or binder.

[0048] ⑤ Extrusion: The screw rotates, and the wet material is forced through a 5mm mesh screen by the screw, forming strips. Extrusion conditions: Screw extrusion pressure range is 5~10MPa. Screw speed is 15~30rpm. The extrusion die is made of hard alloy or ceramic. By controlling the extrusion equipment parameters (extrusion pressure range 5~10 MPa), 5mm columnar particles are obtained. Insufficient pressure results in loose strips; excessive pressure may overload the equipment.

[0049] ⑥ Pelletizing: The extruded strip material is cut by a rotating cutter at the outlet. The cutter rotates at 150~300 rpm, eventually forming cylindrical wet pellets with a diameter of about 5 mm and a length of about 4~5 mm.

[0050] ⑦ Transfer: The wet pellets after pelleting are quickly transferred to the drying unit via a collection tray (material layer thickness 10cm~15cm), with the transfer time controlled within 10 minutes. Because the surface of the wet pellets is coated with a PEG film, brief exposure will not cause significant oxidation.

[0051]

Unit Two: Drying - Cooling - Grinding

[0052] ⑨ Cooling: The dried granules enter the cooling zone directly inside the equipment. This cooling zone adopts a fluidized bed design, where the material is in continuous motion. Circulating cooling water is introduced into the equipment jacket, allowing the granules to cool down rapidly to below 30°C.

[0053] ⑩ Crushing: After cooling, the particles enter the crusher for crushing. The rotating auger further crushes the particles and then passes them through a 1mm diameter extrusion screen below the rotating auger to obtain intermediate particles with a diameter of less than 1mm.

[0054]

Unit 3: Sieving

[0055] The intermediate particles (within 1 mm) obtained from extrusion are coarsely sieved using a 100-mesh sieve (approximately 150 μm aperture) to ensure that the particles passing through the sieve are ≤150 μm. Then, they are precisely sieved using a 150-mesh sieve (approximately 106 μm aperture) to ensure that the overall particle size distribution is concentrated between 50 and 80 μm, thus achieving precise control of D50. Simultaneously, larger particles that do not pass through the sieve are recovered and re-granulated. This process is repeated to ensure that the particle size is concentrated within the target range.

[0056] S3. Powder Mixing: Under inert gas protection, the granulated molybdenum powder and titanium powder are mixed in a certain proportion. The mixer speed is 10~15 rpm, and the mixing time is 2~5 hours.

[0057] S4. Degassing treatment: Stepwise heating. After heating to 250~350℃, hold for 3~5 hours, then heat to 400~600℃, under a vacuum of 2×10⁻⁶. -3 Incubate at Pa for 36-48 hours.

[0058] S5. Hot isostatic pressing: Stepwise heating. Heat to 400-600℃ and hold for 1-3 hours, then heat to 1000-1300℃. Maintain a vacuum of 2×10⁻⁶. -3 Under conditions of Pa and pressure of 100~200MPa, keep warm for 5~15h.

[0059] S6. Vacuum heat treatment: Vacuum degree 10 -2 Pa ~10 -3 Pa, heating temperature 900~1300℃, holding for 5~15h, to obtain MoTi alloy material.

[0060] Example The following examples describe the disclosure of this invention in more detail. These examples are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of this disclosure. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are based on weight, and all reagents used in the examples are commercially available or synthesized by conventional methods and can be used directly without further processing. The instruments used in the examples are also commercially available.

[0061] Example 1 S1. Select Mo powder (purity ≥3N5, particle size 3~5μm) and Ti powder (purity ≥3N, particle size D50 = 69μm).

[0062] S2. Under an inert gas (Ar) atmosphere, Mo powder is dry-extruded and granulated without adding any binder. The extrusion pressure is set to 10 MPa, and a cemented carbide die is used with an outlet mesh size of 1 mm. Extrusion granulation yields Mo granulated powder with a diameter of less than 1 mm. Then, the powder is coarsely sieved using a 100-mesh sieve to remove large particles, and then sieved again using a 150-mesh sieve. The sieved powder is the target powder. At this point, the target Mo powder matches the D50 particle size of the Ti powder, with a D50 = 76 μm. Large particles that do not pass through the sieve are collected and fed back into the equipment for extrusion granulation, and this process is repeated.

[0063] S3. Under an inert gas protective atmosphere, the granulated Mo powder and Ti powder are mixed in the planned ratio (Ti = 50 ± 10 at%). The speed of the metal powder mixer is set to 10 rpm, and the mixing time is 5 hours, finally obtaining a uniform mixed powder.

[0064] S4. The above-mentioned mixed powder is placed into a large packaging unit, and degassed using a degassing device. Due to the large size of the packaging unit, a stepped heating method is used to minimize the temperature difference between the core and the outside of the powder inside the unit. First, the packaging unit is heated from room temperature to 350°C and held at that temperature for 3 hours. Then, it is heated to 400°C, and the temperature is maintained at a vacuum of 2 x 10⁻⁶. - 3 After Pa, start heat preservation for 48 hours.

[0065] S5. The degassed cladding is then subjected to hot isostatic pressing to densify the internal powder. Similar to the degassed treatment, a stepped heating method is used. First, the cladding is heated from room temperature to 600°C and held for 2 hours. Then, it is further heated to 1300°C and held at 200 MPa for 5 hours. After completion, the cladding is removed, yielding the internal MoTi alloy ingot.

[0066] S6. Finally, the obtained alloy ingot is heat-treated under high vacuum conditions. The temperature is increased to 1300℃ at a heating rate of 5℃ / min, held for 5 hours, and then naturally cooled to room temperature to obtain the MoTi alloy target.

[0067] Example 2 S1. Select Mo powder (purity ≥3N5, particle size 3~5μm) and Ti powder (purity ≥3N, particle size D50 = 69μm).

[0068] S2. Under an inert gas (Ar) atmosphere, Mo powder is wet-extruded and granulated, with thermally decomposable polyethylene glycol (PEG20000) binder added during the process. The extrusion pressure is set to 10 MPa, a ceramic die is used, and the outlet mesh size is 1 mm. Extrusion granulation yields Mo granulated powder with a diameter of less than 1 mm. Then, the powder is coarsely sieved using a 100-mesh sieve to remove large particles, and then sieved again using a 150-mesh sieve. The sieved powder is the target powder. At this point, the D50 particle size of the target Mo powder matches that of the Ti powder, with a D50 = 72 μm. Large particles that do not pass through the sieve are collected and fed back into the equipment for extrusion granulation, and this process is repeated.

[0069] S3. Under an inert gas protective atmosphere, the granulated Mo powder and Ti powder are mixed in a certain proportion (Ti = 50 ± 10 at%). The speed of the metal powder mixer is set to 15 rpm, and the mixing time is 2 hours, finally obtaining a uniform mixed powder.

[0070] S4. The above-mentioned mixed powder is placed into a large packaging unit and degassed using a degassing device. Heating is also performed using a stepped heating method. First, the packaging unit is heated from room temperature to 250°C and held at that temperature for 5 hours. Then, it is heated further to 600°C, and a vacuum degree of 2x10⁻⁶ is achieved. -3 After Pa, start heat preservation for 36 hours.

[0071] S5. The degassed cladding is then subjected to hot isostatic pressing to densify the internal powder. A stepped heating method is used. First, the cladding is heated from room temperature to 600°C and held for 2 hours. Then, it is heated to 1000°C and held at 100 MPa for 15 hours. After completion, the cladding is removed to obtain the internal MoTi alloy ingot.

[0072] S6. Finally, the above alloy ingot is heat-treated under high vacuum conditions. The temperature is increased to 900℃ at a heating rate of 5℃ / min, held for 15 hours, and then naturally cooled to room temperature to obtain the MoTi alloy target.

[0073] Comparative Example 1 The process steps of Comparative Example 1 and Example 1 are basically the same. The main difference is that in Comparative Example 1, the Mo powder is not granulated (step S2 is removed) and is directly mixed with the Ti powder.

[0074] Comparative Example 2 The process steps of Comparative Example 2 and Example 2 are basically the same. The main difference is that in step S2, the molybdenum powder is granulated by wet extrusion under atmospheric conditions.

[0075] Comparative Example 3 The process steps of Comparative Example 3 and Example 2 are basically the same, the main difference being that in step S2, the binder is PF (phenolic resin).

[0076] Comparative Example 4 The process steps of Comparative Example 4 and Example 1 are basically the same. The main difference is that in step S2, a steel extrusion die is used instead of the ceramic extrusion die in Example 1.

[0077] Experimental Examples The physical properties of the original Mo powder, the original Ti powder, and the granulated Mo powder prepared in step 2 of Example 1 were tested, and the test results are shown in Table 1.

[0078] Table 1: Comparison of Powder Physical Properties

[0079] The particle size was tested using laser diffraction, and the specific test method is in accordance with GB / T 19077-2024. The test method for tap density is mechanical vibration method, and the specific test method refers to GB / T 5162-2021.

[0080] The metal targets prepared in Examples 1-2 and Comparative Examples 1-4 were tested, and the test results are shown in Table 2.

[0081] Table 2: Test Results of Metal Sputters

[0082] The standard deviation of the Mo / Ti atomic ratio is the relative standard deviation of the Mo / Ti atomic ratio calculated from multiple (multi-point) ICP-OES tests on the same sample. The resistivity of the target material is tested using the four-probe method, and the specific test method is in accordance with GB / T 5167-2018.

[0083] The term "batch qualified" as used in this invention refers to the ability of the product to stably and repeatedly meet all the technical specifications of the target material simultaneously. The technical specifications of the target material include: purity ≥ 99.97%; O < 1000 ppm; C < 200 ppm; Fe < 200 ppm; standard deviation ≤ 1 at%; and target material resistivity ≤ 50 μΩ·cm.

[0084] In the technical specifications of the sputtering target, particularly the high uniformity of composition (standard deviation of Mo / Ti atomic ratio ≤ 1 at%), although in actual production it is possible to obtain individual samples with uniform composition through extreme condition control or accidental factors, this is an uncontrollable situation and does not fall within the scope of reliable industrial processes. Therefore, within the evaluation system of this invention, its batch pass rate is zero.

[0085] The data in the table above shows that: Examples 1 and 2 demonstrate that the delamination problem can be solved by changing the physical morphology of a single component (Mo powder). The total amount of associated impurities (C, O, Fe) is controlled at extremely low levels, the target purity is ≥99.97%, and the atomic ratio standard deviation is <1 at%, indicating highly uniform composition throughout the target. The bulk resistivity of the target is ≤42 μΩ·cm, providing the necessary foundation and fundamental prerequisite for ultimately obtaining high-performance (low resistivity) thin films.

[0086] Comparative Example 1: Without granulation of Mo powder, the mixed powder underwent stratification and segregation, and the uniformity of the composition of the three batches of alloy ingots prepared was not up to standard (standard deviation > 2 at%), which also resulted in a significant increase in the resistivity of the target material.

[0087] Comparative Example 2: Under atmospheric conditions, Mo oxidation was severe, resulting in an O content of over 1500 ppm in the product, exceeding the technical specifications, and the resistivity of the target material was extremely high.

[0088] Comparative Example 3: When using phenolic resin (PF) binder, because phenolic resin is a thermosetting resin, it carbonizes rather than completely decomposes during the subsequent degassing and sintering process, resulting in a carbon residue of more than 600 ppm in the final target material, which exceeds the technical specification range, and the resistivity of the target material body is very high.

[0089] Comparative Example 4: When using a standard steel mold for granulation, the mold introduces metallic impurities, with Fe content exceeding 300 ppm, surpassing the technical specifications. This results in reduced product purity and increased resistivity of the target material.

[0090] The above data results indicate that: As can be seen from Comparative Example 1 and Example 1, "molybdenum powder granulation" is a decisive step in achieving particle size matching and eliminating delamination by raising the lower limit of the tap density of molybdenum powder to coincide with the density range of titanium powder, thus enabling the target material to have low resistivity (≤42 μΩ·cm) and high compositional uniformity (standard deviation <1 at%).

[0091] Examples 1-2 and Comparative Examples 2-4 show that an inert atmosphere, a special binder, and a mold are key control conditions to ensure that the above-mentioned properties are not contaminated or damaged by impurities.

[0092] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a large-size molybdenum-titanium alloy target, characterized in that, Includes the following steps: S1. Select raw materials: molybdenum powder and titanium powder; The particle size of the molybdenum powder is 3~5μm, and the tap density of the molybdenum powder is 1.8~2.2 g / cm³. The tap density of titanium powder is 2.0 - 2.5 g / cm³, and the D50 of titanium powder is 20 - 100 μm; S2. Under the protection of inert gas, molybdenum powder is granulated through a granulation process to prepare granulated molybdenum powder. The particle size and tap density of the granulated molybdenum powder are matched with those of the titanium powder. The tap density of granulated molybdenum powder is 2.2~2.8 g / cm³, and the D50 of granulated molybdenum powder is 20~100μm; S3. Under the protection of inert gas, granulated molybdenum powder and titanium powder are mixed in proportion. S4. Degas the mixed powder; S5, sintered into ingots by hot isostatic pressing; S6. Vacuum heat treatment is performed on the ingot to obtain a large-size molybdenum-titanium alloy target.

2. The method for preparing large-size molybdenum-titanium alloy targets according to claim 1, characterized in that, In S1, the purity of molybdenum powder is ≥99.95%, and the purity of titanium powder is ≥99.9%.

3. The method for preparing large-size molybdenum-titanium alloy targets according to claim 2, characterized in that, In S2, the D50 of granulated molybdenum powder is 50-80 μm.

4. The method for preparing large-size molybdenum-titanium alloy targets according to claim 1, characterized in that, In S2, the granulation process is selected from any one of extrusion granulation, spray granulation, and rolling granulation. The extrusion granulation process is either dry extrusion granulation or wet extrusion granulation.

5. The method for preparing large-size molybdenum-titanium alloy targets according to claim 4, characterized in that, The extrusion pressure in the extrusion granulation process is 5 ~ 10 MPa; The material of the extrusion die is selected from any one of cemented carbide, ceramic material, or die steel with ceramicized surface treatment; During the extrusion process, coarse particles with a diameter of less than 5 mm are first prepared, and then intermediate particles with a diameter of less than 1 mm are further prepared. Then, the particles are first screened with a 100-mesh sieve to remove large-sized particles, and then screened with a 150-mesh sieve. The powder that passes through the sieve is granulated molybdenum powder.

6. The method for preparing large-size molybdenum-titanium alloy targets according to claim 5, characterized in that, The dry extrusion granulation process includes feeding, extrusion, coarse crushing, fine granulation, and screening; During the extrusion process, the extrusion pressure is 5~10MPa, and the extruded powder appears as blocks or flakes; During the coarse crushing process, the lumpy or flaky material formed by compression is crushed into coarse particles with a diameter of less than 5 mm. During the finishing process, the coarse particles are further crushed into intermediate particles with a diameter of less than 1 mm.

7. The method for preparing large-size molybdenum-titanium alloy targets according to claim 5, characterized in that, The wet extrusion granulation process includes the following steps: feeding, mixing, aging, extrusion, pelleting, transfer, drying, cooling, crushing, and sieving. During the mixing process, a binder is added to the molybdenum powder. The binder is selected from one or more of polyethylene glycol, polyvinyl alcohol, and paraffin wax; wherein the polyethylene glycol is polyethylene glycol PEG-20000; and the polyvinyl alcohol is PVA 1788 type polyvinyl alcohol with a degree of polymerization of 1600-1800 and a degree of alcoholysis of 87%-89%. During the extrusion process, the screw extrusion pressure ranges from 5 to 10 MPa, extruding molybdenum powder into strips with a diameter of less than 5 mm; During the drying process, the temperature is increased in stages, with a drying temperature of 60~100℃; During the crushing process, molybdenum powder particles are crushed into intermediate particles with a diameter of less than 1 mm.

8. The molybdenum-titanium alloy target prepared by the method for preparing large-size molybdenum-titanium alloy targets according to any one of claims 1-7, characterized in that, The standard deviation of the Mo / Ti atomic ratio is ≤1 at.

9. The large-size molybdenum-titanium alloy target material according to claim 8, characterized in that, The molybdenum-titanium alloy target material has a purity of ≥99.97%; O content <750ppm; C content <30ppm; Fe content <100ppm; and resistivity ≤42μΩ·cm.

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