Method and system for spheroidization and grading of molybdenum-based solid precursor powder

Abstract

The application discloses a kind of spheroidization and grading method and system of molybdenum series solid precursor powder, it is related to semiconductor thin film deposition material preparation and processing technical field.The method includes: S1, in the condition of anhydrous oxygen-free atmosphere and low temperature, by high-speed airflow driving powder particles collide with each other to carry out contactless self-ablation spheroidization;S2, by airflow classification, the spheroidized powder is separated into large particle size fraction and small particle size fraction according to particle size;S3, the on-line electrostatic elimination treatment is carried out to the classified powder to reduce the surface static charge of particle;S4, after eliminating static electricity, two kinds of particle size fractions are mixed according to predetermined proportion and filled to precursor transport container.The system includes airflow spheroidization device, airflow classification device, electrostatic elimination device and mixing and filling device.The application is free of mechanical contact pollution throughout the process, eliminates electrostatic agglomeration, and the space occupancy rate reaches 78% to 84%, which significantly improves the stability of ALD precursor carrier gas delivery, and is suitable for advanced semiconductor ALD thin film deposition process.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor thin film deposition material preparation and processing technology, and specifically relates to a method and system for spheroidizing and grading molybdenum-based solid precursor powder. Background Technology

[0002] As semiconductor integrated circuit manufacturing processes advance to 3nm and below, molybdenum-based solid precursors, such as molybdenum dioxide (MoO2Cl2) and molybdenum pentachloride (MoCl5), are increasingly widely used in advanced ALD (Atomic Layer Deposition) processes to prepare ultrathin molybdenum metal layers and barrier layers. The ALD process places extremely stringent requirements on the vapor pressure output stability, purity, and filling uniformity of the precursors.

[0003] However, molybdenum-based solid precursors generally exhibit strong deliquescence, corrosiveness, and sublimation properties. Currently, traditional solid powder processing and filling methods face the following severe challenges: (1) Irregular morphology and excessive flow resistance: Coarse powder raw materials usually exhibit irregular needle-like or polygonal plate-like morphology. After being filled into the transport cylinder, the porosity is uneven, and the carrier gas flow channel is prone to serious "bridging phenomenon" or local flow channel blockage, resulting in unstable output of ALD feed saturated vapor pressure, which seriously affects the uniformity of wafer film formation.

[0004] (2) Electrostatic agglomeration and graded segregation failure: When using mechanical grinding or graded sieving for particle blending, high-purity molybdenum-based powders are prone to generating tens of thousands of volts of triboelectric static electricity during friction and airflow shearing. Severe electrostatic repulsion not only causes "pseudo-agglomeration"—that is, small particles form large particle aggregates due to electrostatic adsorption, destroying the carefully designed bimodal particle size skeleton structure—but also causes the powder to adhere severely to the conveying pipeline and the inner wall of the cylinder, resulting in a significant decrease in mixing uniformity.

[0005] (3) Risk of introducing metal impurities and water and oxygen: During operation, existing mechanical ball mills and drum mixers are prone to introducing trace amounts of transition metal impurities (such as Fe, Ni, Cr) into ultra-high purity powders due to rigid shaft seal friction and grinding media collision. At the same time, mechanical dynamic seals cannot guarantee the continuous maintenance of an anhydrous and oxygen-free environment (H2O≤0.1ppm, O2≤0.1ppm).

[0006] Therefore, there is an urgent need to develop a method and production system for spheroidizing and grading molybdenum precursors that can achieve efficient and non-destructive spheroidization, completely eliminate static electricity, and avoid contact with metal dynamic seals in extremely harsh anhydrous and oxygen-free closed environments. Summary of the Invention

[0007] To address the problems in related technologies, this invention proposes a method and system for spheroidizing and grading molybdenum-based solid precursor powders, thereby overcoming the aforementioned technical problems existing in the prior art.

[0008] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: A method for spheroidizing and grading molybdenum-based solid precursor powder, wherein the molybdenum-based solid precursor powder is selected from at least one of molybdenum dichlorodioxide (MoO2Cl2) powder and molybdenum pentachloride (MoCl5) powder; The method includes the following steps: S1: Self-etching spheroidization: In an anhydrous and oxygen-free atmosphere and at low temperature, a high-speed airflow is introduced into the precursor powder, causing the powder particles to collide with each other in the airflow to perform non-contact self-etching spheroidization and obtain spherical particles. S2: Airflow classification, the powder after spheroidization in step S1 is separated into a first particle size fraction and a second particle size fraction by airflow classification, the particle size of the second particle size fraction is smaller than that of the first particle size fraction. S3: Neutralization and electrostatic elimination. The powder after classification in step S2 is subjected to online electrostatic elimination treatment to reduce the accumulation of electrostatic charge on the surface of powder particles. S4: The first and second particle size fractions, after being destaticated in step S3, are mixed in a predetermined ratio and filled into the precursor cylinder.

[0009] As a preferred technical solution, before step S2, the powder after spheroidization in step S1 is subjected to a preliminary electrostatic elimination treatment to reduce the accumulation of electrostatic charge on the surface of the powder particles.

[0010] As a preferred technical solution, the purity of the precursor powder is not less than 99.999%.

[0011] As a preferred technical solution, in step S1, the embrittlement temperature range of the low-temperature environment is -10°C to 15°C, and the flow velocity of the high-speed airflow in the spheroidizing cavity is subsonic to supersonic, reaching 0.8Mach to 1.5Mach.

[0012] As a preferred technical solution, in step S1, the high-speed gas flow is a high-purity inert gas that has undergone multi-stage dehydration and deoxygenation purification. The inert gas is selected from at least one of high-purity nitrogen (N2) and high-purity argon (Ar). The purity of the inert gas is not less than 99.9999%, the moisture content is not higher than 50 ppb, and the oxygen content is not higher than 50 ppb.

[0013] As a preferred technical solution, in step S1, the surface roughness Ra of the inner wall of the spheroidizing cavity used for self-erosion spheroidization is not higher than 0.1 μm, and the inner wall material of the spheroidizing cavity is selected from one of super mirror stainless steel and corrosion-resistant Hastelloy.

[0014] As a preferred technical solution, in step S1, the spherical particles have a roundness greater than 0.85.

[0015] As a preferred technical solution, in step S2, the median particle size of the first particle size fraction is 150 μm to 250 μm, and the median particle size of the second particle size fraction is 15 μm to 30 μm.

[0016] As a preferred technical solution, both the online electrostatic elimination treatment and the preliminary electrostatic elimination treatment are achieved through bipolar corona ion neutralization. The positive and negative balanced ion flow generated by alternating discharge neutralizes the surface charge of the powder particles, thereby eliminating the triboelectric static electricity and induced static electricity on the particle surface.

[0017] As a preferred technical solution, the preliminary static electricity elimination treatment is as follows: Between step S1 and step S2, the spheroidized powder is passed through a first-stage neutralizer, where a positive and negative balanced ion flow is used to eliminate the triboelectric static electricity and induced charge generated by the spheroidization collision and airflow shearing.

[0018] As a preferred technical solution, the online static electricity elimination process is as follows: Between steps S2 and S4, the first and second particle size fractions after grading are passed through a second-stage neutralizer, where a positive and negative balanced ion flow is used to eliminate the secondary tribostatic charge generated in the spheroidized powder during the grading process.

[0019] As a preferred technical solution, the alternating corona discharge voltage range of the first-stage neutralizer and the second-stage neutralizer is 4.5kV to 8.0kV, and the alternating frequency is 20Hz to 100Hz.

[0020] As a preferred technical solution, the discharge electrodes of the first-stage neutralizer and the second-stage neutralizer are respectively provided with anti-dust deposition purge gas rings coaxial with them. The purge gas rings introduce a small amount of high-purity inert gas into the neutralizer to form a protective gas curtain.

[0021] As a preferred technical solution, after static electricity elimination, the residual electrostatic charge density on the surface of the spheroidized powder is no higher than 0.05 μC / m. 2 The absolute value of the residual voltage on the surface is not higher than 100V.

[0022] As a preferred technical solution, in step S4, the mixing mass ratio of the first particle size fraction to the second particle size fraction is 7:3 to 8:2.

[0023] As a preferred technical solution, in step S4, the mixing is carried out in a low temperature environment of -10℃ to 10℃, and the precursor cylinder is an atomic layer deposition (ALD) precursor cylinder.

[0024] As a preferred technical solution, after filling in step S4, the space occupancy rate of the powder accumulation in the precursor cylinder is 78% to 84%.

[0025] As a preferred technical solution, when high-purity carrier gas is introduced into the ALD precursor cylinder filled with the powder packing, the local pressure drop ΔP corresponding to the powder packing bed and the carrier gas flow rate Q satisfy the following relationship: ΔP / Q≤1.2Pa / (sccm·cm).

[0026] As a preferred technical solution, in step S4, the mixing is carried out in a mixing vessel equipped with an internal stirring paddle. The surface of the stirring paddle is coated with a high-density soluble polytetrafluoroethylene (PFA) coating. The driving end of the stirring paddle is driven by a non-metallic flexible magnetic coupler located outside the vessel body, which is a shaftless, non-contact magnetic drive.

[0027] This invention also proposes a spheroidization and gradation system for molybdenum-based solid precursor powder, comprising: The airflow spheroidizing device is configured to drive precursor powder with high-speed airflow under anhydrous and oxygen-free atmosphere and low temperature conditions, so that the powder particles collide with each other in the airflow to perform non-contact self-eradication spheroidization. An airflow classification device, connected to the airflow spheroidizing device, is used to separate the spheroidized powder into a first particle size fraction and a second particle size fraction according to particle size, wherein the particle size of the second particle size fraction is smaller than that of the first particle size fraction. An electrostatic eliminator is installed upstream and / or downstream of the airflow classification device to eliminate the accumulation of electrostatic charge on the surface of powder particles online. A mixing and filling device, connected downstream of the static elimination device, is used to mix the first particle size fraction and the second particle size fraction after static elimination in a predetermined ratio, and to fill the mixed powder into the precursor cylinder.

[0028] As a preferred technical solution, the airflow spheroidizing device is a cyclone spheroidizing cavity, which includes a cylinder, a cooling jacket covering the outside of the cylinder for temperature control, at least two opposing collision nozzles symmetrically arranged on the side wall of the cylinder, and an inverted cone-shaped reflux guide cone arranged at the bottom of the inner cavity of the cylinder for guiding substandard particles to tumble upwards and be repeatedly reshaped.

[0029] As a preferred technical solution, the central axis of the opposing collision nozzles forms a spatial angle of 15° to 60° with the horizontal sectional plane of the cylinder; the surface roughness Ra of the inner wall of the cylinder is not higher than 0.1μm, and the inner wall material is selected from one of ultra-mirror stainless steel and corrosion-resistant Hastelloy.

[0030] As a preferred technical solution, the airflow classification device is a cyclone grading separator, which includes a primary cyclone cutter and a secondary high-efficiency cyclone separator connected in series.

[0031] As a preferred technical solution, the static electricity elimination device includes: The first-stage neutralizer is connected in series between the airflow spheroidizing device and the airflow grading device to eliminate the triboelectric static electricity and induced charge generated during the spheroidizing process; The second-stage neutralizer is connected in series between the airflow classification device and the mixing and filling device to eliminate secondary tribostatic electricity generated during the classification process.

[0032] As a preferred technical solution, both the first-stage neutralizer and the second-stage neutralizer include: The main body of the pipe is airtightly connected to the delivery pipeline at both ends via semiconductor-grade VCR flanges; Positive corona discharge electrodes and negative corona discharge electrodes are symmetrically arranged on the inner wall of the main body of the lumen; A dust-prevention purging ring is coaxially disposed around the discharge electrode and is used to introduce a small amount of high-purity inert gas into the cavity to form a protective gas curtain.

[0033] As a preferred technical solution, the positive corona discharge electrode and the negative corona discharge electrode are platinum-iridium alloy electrodes or heavily doped single-crystal silicon electrodes that are resistant to high temperature and high chemical corrosion.

[0034] As a preferred technical solution, the mixing and filling device includes a low-temperature gradation mixing vessel, the interior of which is equipped with a stirring paddle, the surface of which is coated with a high-density soluble polytetrafluoroethylene (PFA) coating, and the driving end of the stirring paddle is driven by a non-metallic flexible magnetic coupler located outside the vessel body for shaftless non-contact magnetic drive.

[0035] As a preferred technical solution, this system also includes: An anhydrous and oxygen-free feeding mechanism is used to feed the precursor powder raw material into the airflow spheroidizing device under anhydrous and oxygen-free conditions; A high-purity ultra-dry carrier gas source is used to provide the gas flow spheroidizing device with high-purity inert gas that has undergone multi-stage dehydration and deoxygenation purification. The purity of the inert gas is not less than 99.9999%, the moisture content is not higher than 50 ppb, and the oxygen content is not higher than 50 ppb.

[0036] Compared with the prior art, the present invention has the following beneficial effects: (1) By combining low-temperature embrittlement with high-speed airflow self-collision spheroidization, powder shaping without contact with grinding media throughout the process is achieved, which fundamentally avoids the risk of contamination from transition metal impurities (Fe, Ni, Cr, etc.) introduced by mechanical ball milling, and ensures that the precursor powder maintains an ultra-high purity of 5N level (≥99.999%).

[0037] (2) By using a two-stage bipolar corona ion online neutralization system connected in series upstream and downstream of the airflow classification device, primary and secondary triboelectric static electricity are eliminated at two key nodes after spheroidization and after gradation separation, respectively, reducing the residual charge density on the surface of powder particles to 0.05 μC / m. 2 The following method completely solves the problems of "pseudo-agglomeration", wall adhesion and gradation segregation failure caused by electrostatic agglomeration of high-purity powder.

[0038] (3) Through multi-stage airflow classification, an extremely narrow bimodal particle size distribution is achieved (large particle size range of 150μm to 250μm, small particle size range of 15μm to 30μm), and combined with electrostatic gravity self-flow filling, the powder accumulation space occupancy rate in the transport container is as high as 78% to 84%, which significantly improves the stability of ALD carrier gas transport. The local pressure drop to flow rate ratio ΔP / Q≤1.2Pa / (sccm·cm) effectively solves the "bridging phenomenon" and pressure change problem of traditional coarse powder filling.

[0039] (4) The entire process is carried out in a water-free and oxygen-free closed environment (H2O≤0.1ppm, O2≤0.1ppm), and the temperature is precisely controlled by the cooling jacket (embrittlement temperature range -10℃ to 15℃), which effectively suppresses the deliquescence and sublimation loss of molybdenum precursors. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of the invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic flowchart of a method for spheroidizing and grading molybdenum-based solid precursor powder according to the present invention. Figure 2 This is a schematic diagram of the spheroidization and gradation system of a molybdenum-based solid precursor powder according to the present invention. Figure 3 This is a schematic diagram of the airflow spheroidizing device of a molybdenum-based solid precursor powder spheroidizing and grading system according to the present invention. Figure 4This is a schematic diagram of the electrostatic elimination device for a spheroidization and gradation system of molybdenum-based solid precursor powder according to the present invention.

[0042] Among them: 10-anhydrous and oxygen-free feeding mechanism, 20-high-purity ultra-dry air source, 30-airflow balling device, 40-airflow classification device, 50-static elimination device, 60-mixing and filling device; 31-Cylinder body, 32-Cooling jacket, 33-Opposing collision nozzles, 34-Inverted conical reflux guide cone; 41-Primary cyclone cutter, 42-Secondary high-efficiency cyclone separator; 51-First stage neutralizer, 52-Second stage neutralizer, 53-Cavity body, 54-Positive corona discharge electrode, 55-Negative corona discharge electrode, 56-Anti-dust deposition purging ring. Detailed Implementation

[0043] The technical solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0044] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "top", "middle", "inner", etc., which indicate orientation or positional relationship, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the invention.

[0045] Reference Figure 1-3 As shown, the present invention proposes a method for spheroidizing and grading molybdenum-based solid precursor powder, wherein the molybdenum-based solid precursor powder is selected from at least one of molybdenum dichloride (MoO2Cl2) powder and molybdenum pentachloride (MoCl5) powder, and the purity of the precursor powder is not less than 99.999%.

[0046] The method of the present invention includes the following steps: S1: Self-etching spheroidization: In an anhydrous and oxygen-free atmosphere and at low temperature, a high-speed airflow is introduced into the precursor powder, causing the powder particles to collide with each other in the airflow to perform non-contact self-etching spheroidization, thereby obtaining spherical particles, wherein the sphericity of the spherical particles is greater than 0.85.

[0047] S2: Airflow classification, the powder after spheroidization in step S1 is separated into a first particle size fraction and a second particle size fraction by airflow classification, the particle size of the second particle size fraction is smaller than that of the first particle size fraction. S3: Neutralization and electrostatic elimination. The powder after classification in step S2 is subjected to online electrostatic elimination treatment to reduce the accumulation of electrostatic charge on the surface of powder particles. S4: The first and second particle size fractions, after being destaticated in step S3, are mixed in a predetermined ratio and filled into the precursor cylinder.

[0048] Furthermore, before step S2, the powder spheroidized in step S1 is subjected to a preliminary electrostatic elimination treatment to reduce the accumulation of electrostatic charge on the surface of the powder particles.

[0049] In this invention, the term "non-contact self-enameling spheroidization" refers to the process of achieving particle spheroidization solely through the collision, shearing, and surface erosion of powder particles driven by high-speed airflow, without the aid of any mechanical abrasive media (such as grinding balls, grinding discs, etc.). The term "online electrostatic elimination treatment" refers to the real-time electrostatic neutralization treatment of powder particles in the continuous process of powder conveying and processing, rather than performing it under offline static conditions.

[0050] Specifically, in step S1, the embrittlement temperature range of the low-temperature environment is -10℃ to 15℃, and the flow velocity of the high-speed gas in the spheroidizing cavity is subsonic to supersonic, reaching 0.8Mach to 1.5Mach. The high-speed gas in this invention is a high-purity inert gas purified through multi-stage dehydration and deoxygenation. The inert gas is selected from at least one of high-purity nitrogen (N2) and high-purity argon (Ar), and the purity of the inert gas is not less than 99.9999%, the moisture content is not higher than 50 ppb, and the oxygen content is not higher than 50 ppb.

[0051] Specifically, in step S1, the surface roughness Ra of the inner wall of the spheroidizing cavity used for self-erosion spheroidization is not higher than 0.1 μm, and the inner wall material of the spheroidizing cavity is selected from one of super mirror stainless steel and corrosion-resistant Hastelloy.

[0052] In step S2 of the present invention, the airflow classification results in the median particle size of the first particle size fraction being 150 μm to 250 μm and the median particle size of the second particle size fraction being 15 μm to 30 μm.

[0053] In this invention, the preliminary electrostatic elimination treatment and the online electrostatic elimination treatment are achieved through bipolar corona ion neutralization. The positive and negative balanced ion flow generated by alternating discharge neutralizes the surface charge of the powder particles, thereby eliminating the tribostatic and induced static electricity on the particle surface.

[0054] The preliminary static electricity elimination treatment is as follows: Between step S1 and step S2, the spheroidized powder is passed through a first-stage neutralizer, where a positive and negative balanced ion flow is used to eliminate the triboelectric static electricity and induced charge generated by the spheroidization collision and airflow shearing.

[0055] The online static electricity elimination process is as follows: Between steps S2 and S4, the first and second particle size fractions after classification are passed through a second-stage neutralizer, where positive and negative balanced ion currents are used to eliminate the secondary tribostatic charge generated by the particles during the classification process.

[0056] The alternating corona discharge voltage range of the first-stage neutralizer and the second-stage neutralizer is 4.5kV to 8.0kV, and the alternating frequency is 20Hz to 100Hz. After static elimination, the residual electrostatic charge density on the surface of the powder particles is no higher than 0.05μC / m. 2 The absolute value of the residual voltage on the surface is not higher than 100V.

[0057] Specifically, in step S4, the mixing mass ratio of the first particle size fraction to the second particle size fraction is 7:3 to 8:2. The mixing process needs to be carried out in a low-temperature environment of -10℃ to 10℃, and the precursor cylinder is an atomic layer deposition (ALD) precursor cylinder. After filling in step S4, the space occupancy of the powder packing inside the precursor cylinder is 78% to 84%.

[0058] Furthermore, the mixing process is carried out in a mixing vessel equipped with an internal stirring paddle, the surface of which is coated with a high-density soluble polytetrafluoroethylene (PFA) coating, and the driving end of the stirring paddle is driven by a non-metallic flexible magnetic coupler located outside the vessel body for shaftless non-contact magnetic drive.

[0059] In this invention, step S5 is also included, in which high-purity carrier gas is introduced into the ALD precursor cylinder containing the powder packing, and the local pressure drop ΔP corresponding to the powder packing bed and the carrier gas flow rate Q satisfy the following relationship: ΔP / Q≤1.2Pa / (sccm·cm).

[0060] Reference Figure 2-4 As shown, the present invention also proposes a spheroidization and gradation system for molybdenum-based solid precursor powder, comprising: an anhydrous and oxygen-free feeding mechanism 10, a high-purity ultra-dry carrier gas source 20, an airflow spheroidization device 30, an airflow classification device 40, an electrostatic elimination device 50, and a mixing and filling device 60.

[0061] The anhydrous and oxygen-free feeding mechanism 10 of the present invention is used to feed the precursor powder raw material into the airflow spheroidizing device 30 under anhydrous and oxygen-free conditions; the high-purity ultra-dry carrier gas source 20 is used to provide the airflow spheroidizing device 30 with high-purity inert gas that has undergone multi-stage dehydration and deoxygenation purification, wherein the purity of the inert gas is not less than 99.9999%, the moisture content is not higher than 50 ppb, and the oxygen content is not higher than 50 ppb.

[0062] The airflow spheroidizing device 30 of the present invention is configured to drive precursor powder through high-speed airflow under anhydrous and oxygen-free atmosphere and low-temperature conditions, causing the powder particles to collide with each other in the airflow for non-contact self-abrasion spheroidization. Generally, the airflow spheroidizing device 30 of the present invention is a cyclone spheroidizing chamber, which includes a cylinder 31, a cooling jacket 32 ​​covering the outside of the cylinder 31 for temperature control, at least two opposing collision nozzles 33 symmetrically arranged on the side wall of the cylinder 31, and an inverted conical reflux guide cone 34 disposed at the bottom of the inner cavity of the cylinder 31 for guiding substandard particles to tumble upwards and repeat reshaping. The central axis of the opposing collision nozzles 33 forms a spatial angle of 15° to 60° with the horizontal sectional plane of the cylinder 31; the surface roughness Ra of the inner wall of the cylinder 31 is not higher than 0.1 μm, and the inner wall material is selected from ultra-mirror stainless steel and corrosion-resistant Hastelloy.

[0063] The airflow classification device 40 of the present invention is connected to the airflow spheroidizing device 30 and is used to separate the spheroidized powder into a first particle size fraction and a second particle size fraction according to the particle size. The particle size of the second particle size fraction is smaller than that of the first particle size fraction. The airflow classification device 40 of the present invention is a cyclone grading separator, which includes a primary cyclone cutter 41 and a secondary high-efficiency cyclone separator 42 connected in series.

[0064] The electrostatic elimination device 50 of the present invention is disposed upstream and / or downstream of the airflow classification device 40 for online elimination of electrostatic charge accumulation on the surface of powder particles.

[0065] The static electricity elimination device 50 of the present invention includes: The first-stage neutralizer 51 is connected in series between the airflow spheroidizing device 30 and the airflow grading device 40 to eliminate the frictional static electricity and induced charge generated during the spheroidizing process. The second-stage neutralizer 52 is connected in series between the airflow classification device 40 and the mixing and filling device 60 to eliminate secondary tribostatic electricity generated during the classification process.

[0066] The first-stage neutralizer 51 and the second-stage neutralizer 52 of the present invention both include: The main body of the tube 53 is airtightly connected to the delivery pipeline at both ends via semiconductor-grade VCR flanges; Positive corona discharge electrode 54 and negative corona discharge electrode 55 are symmetrically arranged on the inner wall of the main body of the tube 53; The dust-proof purging ring 56 is coaxially arranged around the positive corona discharge electrode 54 and the negative corona discharge electrode 55, and is used to introduce a small amount of high-purity inert gas into the cavity to form a protective gas curtain.

[0067] The positive corona discharge electrode 54 and the negative corona discharge electrode 55 of the present invention are platinum-iridium alloy electrodes or heavily doped single-crystal silicon electrodes that are resistant to high temperature and high chemical corrosion.

[0068] The mixing and filling device 60 of the present invention is connected downstream of the static elimination device 50, and is used to mix the first particle size fraction and the second particle size fraction after static elimination in a predetermined ratio, and fill the mixed powder into the precursor cylinder.

[0069] The mixing and filling device 60 of the present invention includes a low-temperature gradation mixing vessel, and a stirring paddle is provided inside the low-temperature gradation mixing vessel. The surface of the stirring paddle is coated with a high-density soluble polytetrafluoroethylene (PFA) coating. The driving end of the stirring paddle is driven by a non-metallic flexible magnetic coupler disposed outside the vessel body in a shaftless, non-contact magnetic drive.

[0070] The present invention will now be described with reference to specific embodiments.

[0071] Example 1 (Contactless spheroidization and electrostatic-free filling process of molybdenum dioxide (MoO2Cl2)) The material used in this embodiment is coarse molybdenum dioxide (MoO2Cl2) powder with a purity of not less than 99.999%, and its original morphology is irregular needle-like and polygonal flake-like.

[0072] In a sealed environment (H2O≤0.1ppm, O2≤0.1ppm), the high-purity ultra-dry carrier gas source 20 is turned on, and high-purity nitrogen (N2) that has undergone multi-stage dehydration and deoxygenation purification is introduced into the system. The gas purity is not less than 99.9999%, the moisture content is not higher than 50ppb, and the oxygen content is not higher than 50ppb. At the same time, the cooling jacket 32 ​​of the cyclone spheroidizing chamber is turned on to circulate refrigerant, so that the internal temperature of the cylinder 31 is precisely controlled at -5℃.

[0073] The coarse powder precursor is uniformly fed into the cyclone spheroidizing chamber via an anhydrous and oxygen-free feeding mechanism 10. Opposing collision nozzles 33 symmetrically inject a cold carrier airflow carrying powder particles into the collision zone of the chamber at a speed of 1.1 Mach. The spatial angle between the central axis of the nozzle and the horizontal tangent of the cylinder 31 is 30°. In the collision zone, the precursor powder becomes brittle due to low temperature and undergoes violent self-shaping through collisions carried by the high-speed airflow. Powder particles with their surface edges eroded spiral down the inner wall of the cylinder 31 to the bottom, and under the guidance of the inverted conical return flow guide cone 34, continuously tumble upwards back to the collision zone for repeated shaping until the particle sphericity reaches 0.90 or higher. The spherical particles that meet the shaping criteria are carried out by the carrier airflow through the central overflow outlet pipe. The inner wall of the cylinder 31 is made of ultra-mirror-finish 316L stainless steel with Ra≤0.1μm, minimizing the adhesion of powder particles to the wall surface.

[0074] The spheroidized gas-solid two-phase flow first enters the first-stage neutralizer 51. The first-stage neutralizer 51 is airtightly connected to the delivery pipeline at both ends via semiconductor-grade VCR flanges. The inner wall of the pipeline is symmetrically equipped with platinum-iridium alloy positive corona discharge electrodes 54 and negative corona discharge electrodes 55, generating a high-concentration positive and negative balanced bipolar ion flow under an alternating discharge voltage of 5.5 kV and a frequency of 50 Hz. As the suspended precursor powder passes through the discharge region, the large amount of frictional and induced charges accumulated on its surface due to spheroidization collisions and airflow shearing are dynamically neutralized by positive and negative ions, reducing the residual charge density on the particle surface to 0.02 μC / m³. 2 The following is an example of a dust-prevention purge ring 56 surrounding the discharge electrode, which introduces a small amount of ultra-dry nitrogen gas into the cavity at a flow rate of 15 sccm to form a protective gas curtain, effectively preventing the deposition of precursor fine powder on the discharge electrode and causing a discharge short circuit.

[0075] The material after passing through the first-stage neutralizer 51 is introduced into the cyclone grading separator. The cyclone grading separator includes a primary cyclone cutter 41 and a secondary high-efficiency cyclone separator 42 connected in series. By adjusting the cyclone speed and the cutting wheel structure parameters, the material is precisely cut and separated into median particle sizes D. 50 =220μm large particle size fraction (corresponding to the first particle size fraction of this invention) and D 50 The small particle size fraction with a diameter of 22 μm (corresponding to the second particle size fraction of the present invention) is discharged through the top overflow pipe.

[0076] The two powder streams after gradation separation pass through a second-stage neutralizer 52 in gravity feed pipes. The structure and parameters of the second-stage neutralizer 52 are the same as those of the first-stage neutralizer 51 (alternating discharge voltage 5.5kV, frequency 50Hz), used to eliminate the secondary charge generated by the high-speed swirling friction of particles on the inner wall of the cyclone gradation separator. After neutralization, the residual charge density on the surface of both the large-diameter and small-diameter fractions is only 0.02μC / m³. 2 .

[0077] The two streams of destaticated powder, in a mass ratio of 7.5:2.5, are directly fed into a low-temperature gradation mixing vessel (i.e., the mixing and filling device 60 of this invention) at a temperature of -5°C under gravity. The double-cantilevered flexible stirring paddle inside the mixing vessel is coated with a high-density PFA coating. Its drive end is driven by a non-metallic flexible magnetic coupler located outside the vessel body, using a shaftless, non-contact magnetic drive to physically and slowly blend the bimodal powder at a low speed of 30 rpm. The well-mixed graded precursor powder is then gravity-fed into the ALD precursor cylinder below without electrostatic agglomeration.

[0078] Testing revealed that the material occupancy rate inside the cylinder was 81%, and the ratio of the local pressure drop ΔP to the carrier gas flow rate Q corresponding to the powder bed was only 0.6 Pa / (sccm·cm). The flow resistance drop was reduced by 65% ​​compared to the original coarse powder that was not spheroidized or graded. Under the condition of continuous introduction of 100 sccm of ALD high-purity carrier gas, no pressure drop fluctuations were observed during 24 hours of continuous monitoring, and no visible electrostatic adhesion or secondary polycrystalline pseudo-agglomeration was observed on the surface of the powder particles.

[0079] Example 2 (Contactless spheroidization and electrostatic-free filling process of molybdenum pentachloride MoCl5) The material used in this embodiment is coarse molybdenum pentachloride (MoCl5) powder with a purity of not less than 99.999%. Compared with Example 1, MoCl5 has stronger sublimation properties and requires higher temperature control precision.

[0080] Within the closed-loop system, the embrittlement temperature zone inside the cyclone spheroidization chamber is set at 5°C. The inlet gas velocity of the opposing collision nozzle 33 is adjusted to 1.3 Mach, and the carrier gas is switched to high-purity argon (Ar) that has undergone multi-stage dehydration and deoxygenation purification, with a purity of not less than 99.9999% and a moisture and oxygen content not exceeding 50 ppb. The spatial angle between the nozzle's central axis and the horizontal tangent of the cylinder 31 is adjusted to 45° to obtain stronger particle self-collision shear force. After self-erosion spheroidization, the sphericity of the MoCl5 powder particles reaches 0.93.

[0081] After being pre-neutralized online in the first-stage neutralizer 51, the material is sent to the cyclone separator to cut and separate the median particle size D. 50 The particles are divided into a large particle size fraction of 180 μm and a small particle size fraction of 18 μm. The two powder streams then pass through a second-stage neutralizer 52 in gravity-fed pipelines. The alternating discharge voltage of the two-stage neutralizers is set to 6.2 kV, the frequency to 40 Hz, and the air flow rate of the anti-dust-deposition purging ring 56 is 20 sccm. After eliminating the secondary charge generated by the high-speed swirling grinding of the particles on the inner wall of the grading separator, the two powder streams fall directly into the low-temperature grading mixing vessel by gravity in a "monodispersed" state of frictionless electrostatic adhesion and electrostatic attraction.

[0082] At 0℃, the mixing vessel underwent physical mixing at a low speed of 25 rpm without secondary polycrystalline pseudo-agglomeration. After mixing, the graded powder was fed into the ALD precursor cylinder under gravity. Testing showed that the packing space occupancy reached 83%, and the local pressure drop to carrier gas flow rate ratio ΔP / Q = 0.8 Pa / (sccm·cm), demonstrating excellent transport performance and fully meeting the stringent requirements for the transport stability of molybdenum-based precursors in advanced ALD processes below 3nm.

[0083] Comparative Test To verify the beneficial effects of the technical solution of this invention, the following comparative experiments were conducted: I. Comparative Example A: MoO2Cl2 coarse powder was mechanically ball-milled and shaped using a traditional zirconia ball mill (milling time 2 hours, speed 200 rpm), then graded by a vibrating screen, and finally directly filled into steel cylinders without the electrostatic elimination device 50.

[0084] II. The airflow self-erosion spheroidization + two-stage electrical neutralization + low-temperature graded mixing and filling process using the same parameters as in Example 1 of this invention.

[0085] The results of the comparative tests are shown in the table below: .

[0086] As can be seen from the comparison data in the table above, the non-contact airflow spheroidization and electrostatic-free gradation method proposed in this invention is significantly superior to the traditional mechanical ball milling process in all key indicators such as powder purity maintenance, particle sphericity, electrostatic elimination effect, bulk density, and carrier gas delivery stability. It has outstanding substantive features and significant progress.

[0087] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0088] The preferred embodiments of the 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 method for spheroidizing and grading molybdenum-based solid precursor powder, characterized in that, The molybdenum-based solid precursor powder is selected from at least one of molybdenum dichloride powder and molybdenum pentachloride powder; The method includes the following steps: S1: Self-etching spheroidization: In an anhydrous and oxygen-free atmosphere and at low temperature, a high-speed airflow is introduced into the precursor powder, causing the powder particles to collide with each other in the airflow to perform non-contact self-etching spheroidization and obtain spherical particles. The embrittlement temperature range of the low-temperature environment is -10℃ to 15℃, and the flow velocity of the high-speed gas in the spheroidizing cavity is subsonic to supersonic, reaching 0.8Mach to 1.5Mach; the high-speed gas is a high-purity inert gas that has undergone multi-stage dehydration and deoxygenation purification, and the inert gas is selected from at least one of high-purity nitrogen and high-purity argon, with a purity of not less than 99.9999%, a moisture content of not more than 50 ppb, and an oxygen content of not more than 50 ppb; S2: Airflow classification, the powder after spheroidization in step S1 is separated into a first particle size fraction and a second particle size fraction by airflow classification, the particle size of the second particle size fraction is smaller than that of the first particle size fraction. The median particle size of the first particle size fraction is 150 μm to 250 μm, and the median particle size of the second particle size fraction is 15 μm to 30 μm. S3: Neutralization and electrostatic elimination. The powder after classification in step S2 is subjected to online electrostatic elimination treatment to reduce the accumulation of electrostatic charge on the surface of powder particles. The online static electricity elimination process is as follows: The first and second particle size fractions after classification are passed through a second-stage neutralizer, where a positive and negative balanced ion flow is used to eliminate the secondary tribostatic charge generated in the spheroidized powder during the classification process. S4: Mix the first and second particle size fractions after static electricity is eliminated in step S3 according to a predetermined ratio and fill them into the precursor cylinder. The mixing mass ratio of the first particle size fraction to the second particle size fraction is 7:3 to 8:

2.

2. The spheroidization and gradation method according to claim 1, characterized in that, Before step S2, the powder after spheroidization in step S1 is subjected to a preliminary electrostatic elimination treatment to reduce the accumulation of electrostatic charge on the surface of the powder particles.

3. The spheroidization and gradation method according to claim 1, characterized in that, In step S1, the spherical particles have a roundness greater than 0.

85.

4. The spheroidization and gradation method according to claim 2, characterized in that, The preliminary static electricity elimination treatment is as follows: Between step S1 and step S2, the spheroidized powder is passed through a first-stage neutralizer, where a positive and negative balanced ion flow is used to eliminate the triboelectric static electricity and induced charge generated by the spheroidization collision and airflow shearing.

5. The spheroidization and gradation method according to claim 4, characterized in that, The alternating corona discharge voltage range of the first-stage neutralizer is 4.5kV to 8.0kV, and the alternating frequency is 20Hz to 100Hz; after eliminating static electricity, the residual electrostatic charge density on the surface of the spheroidized powder is not higher than 0.05μC / m. 2 The absolute value of the residual voltage on the surface is not higher than 100V.

6. The spheroidization and gradation method according to claim 1, characterized in that, The alternating corona discharge voltage range of the second-stage neutralizer is 4.5kV to 8.0kV, and the alternating frequency is 20Hz to 100Hz; after eliminating static electricity, the residual electrostatic charge density on the surface of the spheroidized powder is not higher than 0.05μC / m. 2 The absolute value of the residual voltage on the surface is not higher than 100V.

7. A spheroidization and gradation system for molybdenum-based solid precursor powder, characterized in that, include: The airflow spheroidizing device is configured to drive precursor powder with high-speed airflow under anhydrous and oxygen-free atmosphere and low temperature conditions, so that the powder particles collide with each other in the airflow to perform non-contact self-eradication spheroidization. The embrittlement temperature range under the low-temperature conditions is -10℃ to 15℃. The flow velocity of the high-speed gas in the gas spheroidizing device is subsonic to supersonic, reaching 0.8Mach to 1.5Mach. The high-speed gas is a high-purity inert gas that has undergone multi-stage dehydration and deoxygenation purification. The inert gas is selected from at least one of high-purity nitrogen and high-purity argon. The purity of the inert gas is not less than 99.9999%, the moisture content is not higher than 50ppb, and the oxygen content is not higher than 50ppb. An airflow classification device, connected to the airflow spheroidizing device, is used to separate the spheroidized powder into a first particle size fraction and a second particle size fraction according to particle size, wherein the particle size of the second particle size fraction is smaller than that of the first particle size fraction. The median particle size of the first particle size fraction is 150 μm to 250 μm, and the median particle size of the second particle size fraction is 15 μm to 30 μm. An electrostatic eliminator is installed upstream and / or downstream of the airflow classification device to eliminate the accumulation of electrostatic charge on the surface of powder particles online. A mixing and filling device, connected downstream of the static elimination device, is used to mix the first particle size fraction and the second particle size fraction after static elimination in a predetermined ratio, and fill the mixed powder into the precursor cylinder. The mixing mass ratio of the first particle size fraction to the second particle size fraction is 7:3 to 8:2; The static electricity elimination device includes: The first-stage neutralizer is connected in series between the airflow spheroidizing device and the airflow grading device to eliminate the triboelectric static electricity and induced charge generated during the spheroidizing process; The second-stage neutralizer is connected in series between the airflow classification device and the mixing and filling device to eliminate secondary tribostatic electricity generated during the classification process.

8. The spheroidizing and grading system according to claim 7, characterized in that, The airflow spheroidizing device is a cyclone spheroidizing chamber, which includes a cylinder, a cooling jacket covering the outside of the cylinder for temperature control, at least two opposing collision nozzles symmetrically arranged on the side wall of the cylinder, and an inverted cone-shaped reflux guide cone arranged at the bottom of the inner cavity of the cylinder for guiding substandard particles to tumble upwards and be repeatedly reshaped.

9. The spheroidizing and grading system according to claim 7, characterized in that, The airflow grading device is a cyclone grading separator, which includes a primary cyclone cutter and a secondary high-efficiency cyclone separator connected in series.

10. The spheroidizing and grading system according to claim 7, characterized in that, Both the first-stage neutralizer and the second-stage neutralizer include: The main body of the pipe is airtightly connected to the delivery pipeline at both ends via semiconductor-grade VCR flanges; Positive corona discharge electrodes and negative corona discharge electrodes are symmetrically arranged on the inner wall of the main body of the lumen; A dust-prevention purging ring is coaxially disposed around the discharge electrode and is used to introduce a small amount of high-purity inert gas into the cavity to form a protective gas curtain.

11. The spheroidizing and grading system according to claim 7, characterized in that, Also includes: An anhydrous and oxygen-free feeding mechanism is used to feed the precursor powder raw material into the airflow spheroidizing device under anhydrous and oxygen-free conditions; A high-purity ultra-dry carrier gas source is used to provide the gas flow spheroidizing device with high-purity inert gas that has undergone multi-stage dehydration and deoxygenation purification. The purity of the inert gas is not less than 99.9999%, the moisture content is not higher than 50 ppb, and the oxygen content is not higher than 50 ppb.

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