A molybdenum target material, a preparation method thereof and application thereof

Abstract

The application provides a molybdenum target material and a preparation method and application thereof, relates to the technical field of sputtering target material preparation, and the preparation method of the molybdenum target material comprises the following steps: vacuum hot-pressing sintering of nano molybdenum powder under the condition that the temperature is 1100-1350 DEG C and the pressure is 25-50 MPa to obtain a first molybdenum target blank; hydrogen sintering of the molybdenum target blank under a hydrogen atmosphere at 1400-1650 DEG C to obtain a second molybdenum target blank; and hot isostatic pressing of the second molybdenum target blank under the condition that the pressing pressure is 150-200 MPa and the temperature is 1500-1700 DEG C to obtain the molybdenum target material. The preparation method of the molybdenum target material can realize the comprehensive performance of deep deoxygenation and decarburization, controllable grain size and high density of the molybdenum target material.

Description

Technical Field

[0001] This invention relates to the field of sputtering target preparation technology, and in particular to a molybdenum target, its preparation method and application. Background Technology

[0002] Molybdenum sputtering targets are valued for their high melting point (2620℃), good electrical and thermal conductivity, high mechanical strength, and low coefficient of thermal expansion (5.3×10⁻⁶). -6 mm -1 Due to its compatibility with glass and silicon substrates, molybdenum sputtering targets are widely used in the sputtering deposition of thin-film transistor-liquid crystal displays (TFT-LCDs), semiconductor chips, and solar cells. As semiconductor technology nodes continue to shrink and device integration levels continue to rise, chip manufacturing processes place increasingly stringent demands on the comprehensive performance of molybdenum sputtering targets, particularly in terms of ultra-high purity control (especially extremely low oxygen and carbon impurity content), near-full densification (density ≥99%), and nanoscale uniformity of microstructure. However, due to molybdenum's high melting point and significant work hardening tendency, traditional powder metallurgy sintering processes struggle to achieve complete densification, often resulting in low target density and abnormally large grains. Insufficiently dense molybdenum targets are prone to arc discharge and microparticle spatter during magnetron sputtering, causing film defects and reducing yield; large grains, on the other hand, affect film thickness uniformity and deposition rate. Furthermore, although nanopowders theoretically help refine grains, the extremely high specific surface area of ​​molybdenum nanopowder makes it easy to adsorb oxygen and form a stubborn surface oxide film. At the same time, carbon impurities can easily diffuse from the graphite mold or furnace atmosphere into the target material during high-temperature sintering, leading to an increase in carbon content. Carbon segregation will not only further increase the film resistivity, but also cause grain boundary embrittlement, reduce the mechanical properties and sputtering stability of the target material, and ultimately deteriorate the electrical performance and reliability of the device.

[0003] Currently, the preparation of molybdenum sputtering targets mostly adopts powder metallurgy process, including (1) using powder metallurgy sintering and rolling (forging) combined with heat treatment, (2) pre-sintering molybdenum powder under low atmosphere pressure and then high temperature sintering, (3) molybdenum powder undergoes cold isostatic pressing, sintering and hot isostatic pressing in sequence, (4) molybdenum powder undergoes annealing, cold pressing and hot pressing sintering in sequence to obtain molybdenum blank, and finally the molybdenum blank is placed in the welded sleeve for hot isostatic pressing splicing; (5) nano molybdenum powder surface activation and multi-level gradient sintering combined with carbon-assisted deoxidation technology.

[0004] The above five forming processes each have their own advantages and disadvantages: (1) Process route one uses powder metallurgy sintering followed by rolling (forging) combined with heat treatment. Rolling easily produces banded structures and preferred orientations, resulting in uneven structure. Molybdenum has poor plasticity, and large deformation processing is prone to cracking, resulting in low material utilization (usually <30%). (2) Process route two uses pre-sintering, which will cause the sample to lose a certain sintering activity. The subsequent sintering temperature is high and the time is long, making it easy for crystals to grow abnormally and increasing the C content. In addition, the temperature field of the medium frequency induction sintering furnace is uneven, and the product performance varies greatly at different locations. (3) Process route three uses cold isostatic pressing, sintering and hot isostatic pressing. The density of the cold isostatic pressing billet is low and unevenly distributed. A higher temperature (>1700℃) is required when sintering at normal pressure, which easily leads to abnormal grain growth (average grain size is usually >30μm). Uneven shrinkage easily causes deformation and cracking, resulting in low yield. In the early stage of sintering, the surface pores are closed in advance, and it is difficult for oxygen and carbon inside to be completely discharged. (4) Process route four adopts annealing, cold pressing, hot pressing and then hot isostatic pressing splicing of the cladding. The multi-pass splicing process is complicated, the cladding processing and welding are difficult and costly; the splicing interface bonding strength is insufficient, the pressure shielding of the cladding leads to uneven density, and oxygen and carbon impurities in the cladding are easy to diffuse into the molybdenum target. (5) Process route five adopts nano molybdenum powder surface activation, multi-level gradient sintering combined with carbon-assisted deoxidation. Nano powder is easy to adsorb oxygen, and oxygen pollution is difficult to control; carbon-assisted deoxidation is easy to cause carbon residue, and the carbon content exceeds the standard; nano powder has poor fluidity, which is not conducive to large-size molding, the multi-level gradient sintering process window is narrow, and there is still a lack of mature industrial application. Summary of the Invention

[0005] To address the technical problems existing in the prior art, the present invention aims to provide a molybdenum target material, its preparation method, and its application, achieving comprehensive performance of deep deoxidation and decarbonization, controllable grain size, and high density in the molybdenum target material.

[0006] In a first aspect, the present invention provides a method for preparing a molybdenum target, comprising the following steps: S1. The first molybdenum target blank is prepared by vacuum hot pressing and sintering of nano-molybdenum powder at a temperature of 1100~1350℃ and a pressure of 25~50MPa. S2. The molybdenum target blank is sintered in a hydrogen atmosphere at 1400~1650℃ to obtain a second molybdenum target blank. S3. The second molybdenum target blank is subjected to hot isostatic pressing at a pressing pressure of 150~200MPa and a temperature of 1500~1700℃ to obtain the molybdenum target material.

[0007] In a second aspect, the present invention provides a molybdenum target prepared by the method described in the first aspect; Preferably, the molybdenum target material has a purity >5N, a density ≥99.8%, an average grain size ≤10μm, an oxygen content ≤10ppm, and a carbon content ≤5ppm.

[0008] A third aspect of the present invention provides the application of the molybdenum sputtering target as described in the second aspect in the fabrication of at least one of thin-film transistor-liquid crystal displays, semiconductor chips, and solar cells; Preferably, the molybdenum sputtering target is used in the fabrication of semiconductor chips.

[0009] Compared to existing technologies, the beneficial effects of this application are as follows: (1) Simultaneously taking into account the requirements of high density and fine grains: The present invention first hot-presses (in a lower temperature range) to ensure sintering activity while forming sufficient neck connections between nano-molybdenum particles to construct a stable rigid skeleton structure, retaining a semi-closed through-pore network, and reserving diffusion channels for subsequent deep purification; the subsequent hydrogen sintering completes deep deoxidation and decarbonization in a hydrogen atmosphere, and the grains do not grow abnormally due to pore pinning; finally, through hot isostatic pressing (1500~1700℃, 150~200MPa) isotropic pressing, the residual micropores are completely closed, and the density of the target molybdenum target material reaches more than 99.9%.

[0010] (2) Deep deoxidation: By combining hot pressing pre-deoxidation (oxygen content reduced to <1000ppm) with strong reduction by hydrogen sintering (oxygen content ≤30ppm), the contradiction between incomplete hot pressing deoxidation and difficulty in obtaining high density by hydrogen sintering alone is completely solved. Subsequent hot isostatic pressing does not introduce additional oxygen elements, and the high temperature and high pressure environment promotes the diffusion of residual oxygen to the target surface, ultimately achieving an oxygen content of less than 10ppm, which meets the requirements of high-end sputtering targets.

[0011] (3) Prevention of carbon pollution: In addition, traditional hot pressing or hot isostatic pressing processes often use graphite molds. Under high temperature and high pressure, carbon elements easily diffuse into the molybdenum matrix, leading to an increase in the carbon content of the target material. This invention adopts a process of low-temperature hot pressing followed by hydrogen sintering: In the early stage of hot pressing, the temperature is controlled at a relatively low level (1100~1350℃), which effectively inhibits the excessive diffusion of carbon from the graphite mold into the molybdenum matrix; at the same time, the density obtained in this stage is 85%~90%, retaining a rich semi-closed through-pore network. This through-pore structure plays a key role in the subsequent hydrogen sintering process, that is, the flowing high-purity hydrogen can smoothly penetrate into the depth of the target blank and the surface of the target blank through the through-pores, reacting with carbon impurities and residual carbon C+2H2→CH4. The generated methane gas and gaseous products such as water vapor and carbon monoxide produced by deoxygenation can also be quickly discharged from the blank through these through-pores with the airflow, avoiding secondary pollution or residue caused by the gaseous products being trapped inside. Therefore, hydrogen sintering achieves deep removal of carbon (carbon content ≤5ppm). This process can reduce the carbon content of the target material to below 5 ppm, which is far lower than the carbon content level of the simple hot pressing process (usually >200 ppm), significantly reducing the risk of carbon pollution.

[0012] (4) Maintaining sintering activity: Compared to the process of pre-sintering followed by hot pressing, the diffusion channels on the powder surface disappear after pre-sintering, resulting in a loss of sintering activity. In the present invention, hot pressing followed by hydrogen sintering does not completely densify the molybdenum powder (density 85%~90%), retaining some open pores and lattice defects. It still possesses a certain sintering activity during subsequent hydrogen sintering, which is beneficial for increasing the density to ≥95%. The subsequent hot isostatic pressing utilizes viscoplastic flow and atomic diffusion under high temperature and high pressure to further close the closed pores and achieve complete densification without relying on the initial sintering activity.

[0013] (5) Non-preferred orientation and isotropic properties: Thanks to the optimization of the preparation process, especially the uniform effect of isotropic pressure during hot isostatic pressing, the obtained molybdenum sputtering target exhibits equiaxed crystal characteristics without preferred orientation, effectively eliminating the texture and anisotropy caused by traditional unidirectional pressing or rolling. This microstructural advantage provides a fundamental guarantee for the stability and film thickness uniformity of the subsequent sputtering process.

[0014] (6) Good process compatibility: The hot press furnace, hydrogen sintering furnace and hot isostatic pressing furnace used in this invention are all commonly used equipment in the field of powder metallurgy. No special devices need to be added. The connection between each process is smooth and it is easy to realize industrial mass production. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0016] For any techniques or conditions not specifically specified in the embodiments of this application, the techniques or conditions described in the literature in this field, or the product instructions, shall apply. Devices, instruments, reagents, etc., whose manufacturers are not specified, are all conventional products that can be purchased through legitimate channels. All raw materials used in this application are readily available in the domestic market.

[0017] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0018] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0019] Preparation method of molybdenum sputtering target In a first aspect, the present invention provides a method for preparing a molybdenum target, comprising the following steps: S1. The first molybdenum target blank is prepared by vacuum hot pressing and sintering of nano-molybdenum powder at a temperature of 1100~1350℃ and a pressure of 25~50MPa. S2. The molybdenum target blank is sintered in a hydrogen atmosphere at 1400~1650℃ to obtain a second molybdenum target blank. S3. The second molybdenum target blank is subjected to hot isostatic pressing at a pressing pressure of 150~200MPa and a temperature of 1500~1700℃ to obtain the molybdenum target material.

[0020] Traditional molybdenum target fabrication processes typically employ a pre-sintering followed by hot pressing, which requires high hot pressing temperatures (>2000℃), leading to grain coarsening. This invention first utilizes a low-temperature vacuum hot pressing sintering method (lower temperature range 1100~1350℃) to obtain a first molybdenum target blank with high density and fine grains. This process preserves a semi-closed network of through-holes and a suitable amount of lattice defects in the target blank, effectively suppressing excessive carbon diffusion from the graphite mold to the molybdenum matrix. Subsequently, the first molybdenum target blank undergoes hydrogen sintering treatment (1400~1650℃). Utilizing the strong reducing properties of hydrogen, it smoothly penetrates deep into the target blank through the preserved pores, reacting with residual low-valence molybdenum oxides to generate water vapor that escapes, reducing the oxygen content to below 10 ppm. Simultaneously, the hydrogen carries away trace amounts of carbon that diffused into the vacuum hot pressing stage and the original residual carbon in the form of methane, achieving deep carbon purification (≤5 ppm). Under conditions without external mechanical pressure, sintering densification is driven by a decrease in the system's surface energy. Due to the energy reduction resulting from the decrease in the total system surface area, matter migrates from the particle surface (or grain boundaries, high chemical potential regions) to the particle contact points (neck, low chemical potential regions) through mechanisms such as surface diffusion and grain boundary diffusion. This leads to neck growth, a reduction in particle center-to-center distance, and gradual filling of pores, thereby increasing density. In this scheme, the target blank has already been given high density by the initial vacuum hot pressing sintering, and a strong neck connection has been formed between particles. The subsequent hydrogen sintering is carried out at ≤1650℃, relying mainly on surface energy-driven grain boundary diffusion and matter migration for further densification (density ≥95%), while effectively suppressing abnormal grain growth and controlling the average grain size to below 10 μm. Finally, the second molybdenum target blank after hydrogen sintering is subjected to hot isostatic pressing (1500~1700℃, 150~200MPa). The isotropic pressure completely presses together the micro-nano pores remaining from the previous step, and the material undergoes viscoplastic deformation and atomic diffusion to fill the defects, achieving a density of over 99.9%. This achieves the goal of the target molybdenum target material having high density, ultrafine grains, and extremely low oxygen and carbon content.

[0021] In some embodiments, the average particle size Dv50 of the nano-molybdenum powder is 100~300nm, and the particle size distribution span satisfies Dv90-Dv10<200nm. Preferably, the purity of the nano-molybdenum powder is >5N, the oxygen content is <4000ppm, and the carbon content is <200ppm.

[0022] This scheme controls the average particle size Dv50 of the raw material nano molybdenum powder to be 100~300nm, and the particle size distribution range satisfies Dv90-Dv10<200nm. This particle size design takes into account both sintering activity and grain stability, which can reduce the densification threshold and effectively suppress abnormal grain growth in the subsequent high-temperature process.

[0023] In this invention, Dv10, Dv50, and Dv90 refer to the particle size corresponding to the cumulative particle size distribution number of particles reaching 10%, 50%, and 90% in the cumulative volume distribution curve, respectively. Their physical meaning is that particles with a particle size smaller than this value account for 10%, 50%, and 90%, respectively.

[0024] In some embodiments, the nano-molybdenum powder is pretreated, which includes vacuum drying and sieving in an inert atmosphere with a dew point ≤ -60°C. This pretreatment removes adsorbed water and volatile impurities from the powder surface, breaks up soft agglomerates, thereby reducing the initial oxygen potential and eliminating uneven packing density at the source, providing a raw material guarantee for obtaining a low oxygen content and uniform fine-grained structure.

[0025] In some embodiments, the density of the first molybdenum target blank is 85%~90% and the carbon content is <50ppm; Preferably, the vacuum hot pressing sintering time is 1 to 4 hours.

[0026] In this invention, density refers to the ratio of the actual density of a material to its theoretical density.

[0027] In some embodiments, the dew point of the hydrogen gas is ≤ -50°C; Preferably, the flow rate of the hydrogen gas is 5~25 L / min.

[0028] In some embodiments, the mold used in the vacuum hot pressing sintering is a graphite mold, and the excessive diffusion of carbon into the molybdenum matrix is ​​suppressed by low-temperature vacuum hot pressing sintering.

[0029] In some embodiments, the density of the second molybdenum target blank is ≥95%; Preferably, the hydrogen sintering time is 3-5 hours.

[0030] In some embodiments, during the hydrogen sintering process, the temperature is increased to 1400-1650°C at a heating rate of 2-8°C / min.

[0031] In some embodiments, after the hot isostatic pressing is completed, the temperature is cooled to below 1200°C at a cooling rate of 5~10°C / min.

[0032] This scheme employs the aforementioned cooling method to further suppress grain growth in the high-temperature region, ultimately obtaining an equiaxed, uniform, fine-grained structure without preferred orientation, thus achieving the goal of the target molybdenum sputtering material possessing high density, ultrafine grains, and extremely low oxygen and carbon content.

[0033] In some embodiments, the density of the molybdenum target is ≥99.9%; Preferably, the hot isostatic pressing time is 1 to 6 hours.

[0034] In some embodiments, the method for preparing the molybdenum target includes the following steps: S1. Weighing: Weigh the nano Mo powder as raw material. The purity of the nano Mo powder is >5N, the oxygen content is <4000ppm, and the carbon content is <200ppm. The average particle size (Dv50) of the nano Mo powder is 100~300nm, and the particle size distribution range (Dv90-Dv10) is less than 200nm.

[0035] S2. Vacuum hot pressing sintering: Nano Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 85%~90%; wherein the sintering temperature is 1100~1350℃, the sintering pressure is 25~50MPa, and the sintering time is 1~4h.

[0036] S3. Hydrogen sintering: The first molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a hydrogen atmosphere (dew point ≤ -50℃) to obtain a second molybdenum target blank with a density ≥ 95%. The hydrogen sintering temperature is 1400℃~1650℃, the heating rate is 2~8℃ / min, the holding time is 3~5 hours, and the hydrogen flow rate is 5~25L / min.

[0037] S4. Hot Isostatic Pressing: The second molybdenum target blank obtained in step (3) is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure used for hot isostatic pressing is 150~200MPa, the sintering temperature is 1500~1700℃, and the holding time is 1~6h. After the holding time is completed, the temperature is cooled to below 1200℃ at a cooling rate of 5~10℃ / min to prevent the grains from staying in the high temperature range for too long and causing abnormal growth. A low-oxygen, low-carbon fine-grained molybdenum target material with a purity >5N, density ≥99.9%, average grain size ≤10μm, oxygen content ≤10ppm, and carbon content ≤5ppm is obtained.

[0038] In this invention, the average grain size refers to the size measured using the intercept method according to GB / T 6394-2017 "Method for Determination of Average Grain Size of Metals".

[0039] Molybdenum target In a second aspect, the present invention provides a molybdenum target prepared by the method described in the first aspect; Preferably, the molybdenum target material has a purity >5N, a density ≥99.8%, an average grain size ≤10μm, an oxygen content ≤10ppm, and a carbon content ≤5ppm.

[0040] application A third aspect of the present invention provides the use of the molybdenum sputtering target as described in the second aspect in the fabrication of at least one of thin-film transistor-liquid crystal displays, semiconductor chips, and solar cells; Preferably, the molybdenum sputtering target is used in the fabrication of semiconductor chips.

[0041] The present invention is further illustrated below with specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention: Example 1 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required nano Mo powder as raw material, with an average particle size (D50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0042] S2. Vacuum hot pressing sintering: Nano-Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 85.3%; wherein the sintering temperature is 1100℃, the sintering pressure is 25MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0043] S3. Hydrogen sintering: The obtained first molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1400℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 95.1%.

[0044] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated (to isolate the external carbon source), and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0045] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.94%, an average grain size of 8.9 μm, an oxygen content of 9.3 ppm, a carbon content of ≤5 ppm, and a purity of 5N5.

[0046] Example 2 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0047] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 86.1%; wherein the sintering temperature is 1250℃, the sintering pressure is 25MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0048] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1400℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 95.4%.

[0049] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0050] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.94%, an average grain size of 9.2μm, an oxygen content of 9.0ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0051] Example 3 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0052] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 86.9%; wherein the sintering temperature is 1350℃, the sintering pressure is 25MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0053] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1400℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 95.8%.

[0054] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0055] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.94%, an average grain size of 9.3μm, an oxygen content of 8.8ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0056] Example 4 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0057] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 88.1%; wherein the sintering temperature is 1100℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0058] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1400℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 96.2%.

[0059] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0060] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.96%, an average grain size of 8.7μm, an oxygen content of 8.9ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0061] Example 5 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0062] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 88.9%; wherein the sintering temperature is 1250℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0063] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1400℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 96.7%.

[0064] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0065] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.96%, an average grain size of 8.9μm, an oxygen content of 8.1ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0066] Example 6 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0067] S2 Vacuum Hot Press Sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.4%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0068] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1400℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 97.1%.

[0069] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0070] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.96%, an average grain size of 9.0 μm, an oxygen content of 7.9 ppm, a carbon content of ≤5 ppm, and a purity of 5N5.

[0071] Example 7 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0072] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0073] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1525℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 97.5%.

[0074] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0075] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.96%, an average grain size of 9.2μm, an oxygen content of 7.3ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0076] Example 8 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0077] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0078] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1650℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 97.9%.

[0079] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0080] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.98%, an average grain size of 9.4μm, an oxygen content of 7.1ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0081] Example 9 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0082] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0083] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1650℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 98.0%.

[0084] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0085] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.98%, an average grain size of 9.4μm, an oxygen content of 6.7ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0086] Example 10 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0087] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0088] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1650℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 98.1%.

[0089] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1500℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0090] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.98%, an average grain size of 9.4μm, an oxygen content of 6.2ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0091] Example 11 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0092] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0093] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1650℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 98.0%.

[0094] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 175 MPa, the sintering temperature is 1600℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0095] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.99%, an average grain size of 9.3μm, an oxygen content of 6.3ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0096] Example 12 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0097] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0098] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1650℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 98.0%.

[0099] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 150 MPa, the sintering temperature is 1700℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0100] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.99%, an average grain size of 9.4μm, an oxygen content of 6.3ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0101] Example 13 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0102] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0103] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1650℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 98.0%.

[0104] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 175 MPa, the sintering temperature is 1700℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0105] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.99%, an average grain size of 9.2μm, an oxygen content of 6.2ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0106] Example 14 This embodiment provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0107] S2. Vacuum hot pressing sintering: High-purity Mo powder is pre-formed by vacuum hot pressing sintering to obtain a first molybdenum target blank with a density of 89.5%; wherein the sintering temperature is 1350℃, the sintering pressure is 50MPa, and the vacuum degree is 10. -2 ~10 -3 Pa, sintering time is 2h.

[0108] S3. Hydrogen sintering: The obtained preformed molybdenum target blank is placed in a hydrogen sintering furnace and sintered in a high-purity hydrogen atmosphere (hydrogen dew point ≤ -50℃). The hydrogen sintering temperature is 1650℃, the heating rate is 2℃ / min, the holding time is 4h, and the hydrogen flow rate is 5L / min, to obtain a second molybdenum target blank with a density of 98.0%.

[0109] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 200 MPa, the sintering temperature is 1700℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0110] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and process it to the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.99%, an average grain size of 9.1μm, an oxygen content of 6.3ppm, a carbon content of ≤5ppm, and a purity of 5N5.

[0111] Comparative Example 1 This comparative example provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0112] S2. Cold Isostatic Pressing: The mold filled with Mo powder is placed into a cold isostatic press for cold isostatic pressing according to the requirements. The pressure is 200 MPa and the pressing time is 15 min to obtain a preformed Mo target blank with a density of 72.8%.

[0113] S3. Vacuum hot pressing sintering: The obtained preformed Mo target blank is vacuum hot pressed and sintered at a sintering temperature of 2300℃, a sintering pressure of 50MPa, and a vacuum degree of 10. -2 ~10 -3 Pa, sintering time was 4h. High-purity Mo sputtering target material with density of 98.7%, average grain size of 37μm, oxygen content of 56ppm, carbon content of 105ppm, and purity of 5N5 was obtained.

[0114] Comparative Example 2 This comparative example provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0115] S2. Cold Isostatic Pressing: The mold filled with Mo powder is placed into a cold isostatic press for cold isostatic pressing according to the requirements. The pressure is 200 MPa and the pressing time is 15 min to obtain a preformed Mo target blank with a density of 72.8%.

[0116] S3. Hydrogen Atmosphere Pressureless Sintering: The obtained preformed Mo target blank is placed in a hydrogen sintering furnace for hydrogen sintering. The hydrogen reduction temperature is 2100℃, the holding time is 4h, the hydrogen flow rate is 20L / min, and the hydrogen dew point is ≤-50℃. High-purity Mo target material with a density of 94.2%, an average grain size of 56μm, an oxygen content of 20ppm, a carbon content of 22ppm, and a purity of 5N5 is obtained.

[0117] Comparative Example 3 This comparative example provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0118] S2. Pressureless sintering in a hydrogen atmosphere: High-purity nano-Mo powder is placed in a sintering furnace under hydrogen protection. The hydrogen (hydrogen dew point ≤ -50℃) sintering temperature is 1500℃, the holding time is 4h, and the hydrogen flow rate is 20L / min, to obtain a first molybdenum target blank with a density of 85.9%.

[0119] S3. Vacuum hot pressing sintering: The obtained first molybdenum target blank is vacuum hot pressed and sintered at a sintering temperature of 1900℃, a sintering pressure of 50MPa, and a vacuum degree of 10. -2 ~10 -3 Pa, sintering time was 4h. A second molybdenum target blank with a density of 96.9% was obtained.

[0120] S4. Hot Isostatic Pressing: The obtained second molybdenum target blank is vacuum-encapsulated and then placed in a hot isostatic pressing furnace for pressing and sintering. The pressing pressure is 200 MPa, the sintering temperature is 1700℃, and the temperature and pressure are held for 4 hours. Then, it is cooled to 1200℃ at a cooling rate of 8℃ / min.

[0121] S5. Machining: The hot isostatically pressed molybdenum sputtering material is machined to remove the cladding and to achieve the target size and surface roughness, resulting in a low-oxygen, low-carbon fine-grained molybdenum sputtering material with a density of 99.93%, an average grain size of 24μm, an oxygen content of 12ppm, a carbon content of 40ppm, and a purity of 5N5.

[0122] Comparative Example 4 This comparative example provides a method for preparing a molybdenum target, comprising the following steps: S1. Weighing: Weigh the required high-purity nano Mo powder as raw material, with an average particle size (Dv50) of 200nm, purity of 5N5, oxygen content <4000ppm, and carbon content <200ppm.

[0123] S2. Cold isostatic pressing: The mold filled with Mo powder is placed into a cold isostatic press for cold isostatic pressing according to the requirements. The pressure is 200 MPa and the pressing time is 10 min to obtain the first molybdenum target blank with a density of 72.8%.

[0124] S3. Vacuum Sintering: The first molybdenum target blank, after cold isostatic pressing, is placed in a vacuum-protected sintering furnace. The sintering temperature is 2000℃ and the vacuum degree is 10. -2 ~10 -3Pa, sintering time of 2h, to obtain a second molybdenum target blank with a density of 94.9%.

[0125] S4. Hot rolling: The second molybdenum target billet, which was sintered in vacuum without pressure, is heated and rolled. The billet opening temperature is 1350℃ and the heating time is 45min to obtain a third molybdenum target billet with a density of 98.9%.

[0126] S5. Annealing: The hot-rolled third molybdenum target billet is placed in a hydrogen-protected sintering furnace (hydrogen dew point ≤ -50℃) and annealed under a hydrogen atmosphere at a temperature of 1150℃ for 90 minutes. This yields a high-purity Mo target material with a density of 99.94%, an average grain size of 38μm, an oxygen content of 38ppm, a carbon content of 56ppm, and a purity of 5N5.

[0127] Table 1 shows the main manufacturing processes and performance results of the Mo targets in Examples 1-14 and Comparative Examples 1-4.

[0128] Table 1. Main manufacturing processes and properties of Mo sputtering targets in the examples and comparative examples

[0129] As can be seen from the data comparison in the table, compared with Comparative Example 1 which only uses single hot pressing, Example 1 achieves the same or even higher density while its average grain size, oxygen content, and carbon content are all much lower than those of Comparative Example 1. This is because after introducing hydrogen sintering and hot isostatic pressing in Example 1, not only can a dense skeleton of 85%~90% be obtained by means of the initial hot pressing, but the strong reducing properties of flowing hydrogen can also be used in the subsequent hydrogen sintering to reduce the residual oxygen content to below 10ppm and remove carbon impurities in the form of methane. This overcomes the bottleneck of single hot pressing, which is caused by severe carbon pollution (carbon content is usually >200ppm) due to high temperature diffusion of graphite molds, and the inability to eliminate closed pores, making it difficult to achieve a density of more than 99%. At the same time, the isotropic high pressure of hot isostatic pressing completely closes the micro-nano pores that remain after hot pressing, eliminates structural stress, and increases the density to more than 99.9%, while avoiding grain coarsening caused by increasing the hot pressing temperature in pursuit of high density. Compared to Comparative Example 2, which uses only hydrogen for pressureless sintering, Example 1 exhibits higher density and lower average grain size, oxygen content, and carbon content. This is because Example 1 first constructs a preform with a semi-closed porous network and strong neck connections between particles through low-temperature hot pressing. This provides a stable material migration channel and sintering activity for subsequent hydrogen pressureless sintering, overcoming the shortcomings of single-hydrogen sintering, such as insufficient sintering driving force due to the lack of external pressure, density typically only reaching around 95%, and susceptibility to uneven local shrinkage and abnormal grain growth. Furthermore, the uniform fine-grained framework imparted by the initial hot pressing effectively pins grain boundaries, enabling a density of ≥95% to be obtained after hydrogen sintering at ≤1650℃. Subsequent hot isostatic pressing ultimately achieves the goals of ultra-low oxygen and carbon content, near-complete density, and fine grains. Compared to Comparative Example 3, which involved hydrogen sintering followed by hot pressing and hot isostatic pressing, Example 14 achieved the same or even higher density while having significantly lower grain size, oxygen content, and carbon content. This is because in Comparative Example 3, if hydrogen sintering was performed first, the nano-molybdenum powder would rapidly undergo surface diffusion and grain boundary migration under pressureless conditions, leading to premature closure of the particle neck and rapid sealing of surface pores. Residual oxygen, carbon, and other gaseous products would be difficult to expel, and the grains would grow abnormally due to the lack of pressure constraint, with the average grain size easily exceeding 30 μm. Subsequent hot pressing, due to the loss of sintering activity, not only failed to effectively activate further densification but also introduced new carbon contamination due to the graphite mold. Although hot isostatic pressing followed, the coarse grains and pre-sealed pores could not be completely eliminated, resulting in a still relatively large grain size (>20 μm) for the target material, and the oxygen and carbon content was difficult to reduce to the level of this invention. Compared with Comparative Example 4, which involves vacuum sintering followed by large deformation hot rolling and annealing, the molybdenum sputtering material obtained in Example 14 has superior overall performance and is free of texture.Because the vacuum sintering in Comparative Example 4 involves no external pressure, the grains easily grow abnormally to over 30 μm, and the premature closure of surface pores makes it difficult for internal oxygen and carbon to escape. While subsequent large-deformation hot rolling (60%–90% total deformation) can further close some pores and increase density to over 99%, the rolling process introduces strong crystallographic texture and banded structures, leading to anisotropy of the target material and severely affecting the uniformity of sputtered film thickness. Furthermore, molybdenum has poor plasticity at high temperatures, and large deformation easily causes edge cracks, surface cracks, and even overall cracking, resulting in a material utilization rate of less than 30%. Finally, annealing is required to eliminate residual stress. In contrast, Example 14 eliminates the need for large-deformation rolling, completely avoiding processing cracking and texture problems, achieving high material utilization and a significantly improved yield. It also achieves the synergistic goals of ultra-low oxygen and carbon content, near-full density, and uniform fine grains. Therefore, the molybdenum target preparation method provided by this invention can achieve high density, fine grains, low oxygen content, and low carbon content, obtaining a high-purity Mo target with excellent comprehensive performance and no preferred orientation.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a molybdenum target, characterized in that, Includes the following steps: S1. The first molybdenum target blank is prepared by vacuum hot pressing and sintering of nano-molybdenum powder at a temperature of 1100~1350℃ and a pressure of 25~50MPa. S2. The molybdenum target blank is sintered in a hydrogen atmosphere at 1400~1650℃ to obtain a second molybdenum target blank. S3. The second molybdenum target blank is subjected to hot isostatic pressing at a pressing pressure of 150~200MPa and a temperature of 1500~1700℃ to obtain the molybdenum target material.

2. The method for preparing the molybdenum target according to claim 1, characterized in that, The average particle size Dv50 of the nano molybdenum powder is 100~300nm, and the particle size distribution range satisfies Dv90-Dv10<200nm; Preferably, the purity of the nano-molybdenum powder is >5N, the oxygen content is <4000ppm, and the carbon content is <200ppm.

3. The method for preparing the molybdenum target according to claim 1 or 2, characterized in that, The density of the first molybdenum target blank is 85%~90%, and the carbon content is <50ppm; Preferably, the vacuum hot pressing sintering time is 1 to 4 hours.

4. The method for preparing the molybdenum target material according to any one of claims 1 to 3, characterized in that, The dew point of the hydrogen gas is ≤-50℃; Preferably, the flow rate of the hydrogen gas is 5~25 L / min.

5. The method for preparing the molybdenum target according to any one of claims 1 to 4, characterized in that, The density of the second molybdenum target blank is ≥95%; Preferably, the hydrogen sintering time is 3-5 hours.

6. The method for preparing the molybdenum target according to any one of claims 1 to 5, characterized in that, During the hydrogen sintering process, the temperature is increased to 1400-1650℃ at a heating rate of 2-8℃ / min.

7. The method for preparing the molybdenum target according to any one of claims 1 to 6, characterized in that, After the hot isostatic pressing is completed, the temperature is cooled to below 1200°C at a cooling rate of 5~10°C / min.

8. The method for preparing the molybdenum target according to any one of claims 1 to 7, characterized in that, The density of the molybdenum sputtering target is ≥99.9%; Preferably, the hot isostatic pressing time is 1 to 6 hours.

9. A molybdenum target prepared by the method of any one of claims 1 to 8; Preferably, the molybdenum target material has a purity >5N, a density ≥99.8%, an average grain size ≤10μm, an oxygen content ≤10ppm, and a carbon content ≤5ppm.

10. The application of the molybdenum sputtering target as described in claim 9 in the fabrication of at least one of thin-film transistors-liquid crystal displays, semiconductor chips, and solar cells; Preferably, the molybdenum sputtering target is used in the fabrication of semiconductor chips.

Images