A molybdenum-niobium alloy target and a method for manufacturing the same

Abstract

The application discloses a MoNb alloy target material and a preparation method thereof, and belongs to the technical field of target material preparation. The method comprises the following steps: mixing Mo powder and Nb powder in an inert atmosphere to obtain MoNb mixed powder; pre-burning the MoNb mixed powder under vacuum to obtain MoNb pre-burning alloy powder; performing a cover on the MoNb pre-burning alloy powder according to a cover assembly, degassing, and then placing the MoNb pre-burning alloy powder into a hot isostatic pressing sintering furnace; performing gradient heating to 1250-1400 DEG C, simultaneously performing uniform speed pressure increasing to 110-160 MPa, and then performing heat preservation calcination for 3-5 h; recovering pressure after furnace cooling to obtain a MoNb alloy target blank; and performing grinder processing on the MoNb alloy target blank to obtain a MoNb alloy target material with qualified size. The MoNb alloy target material prepared by the method has high density, is not prone to cracking, has high purity, uniform and small grain structure, good electric conductivity, and excellent sputtering performance.

Description

Technical Field

[0001] This invention belongs to the field of target material preparation technology, specifically relating to a MoNb alloy target material and its preparation method. Background Technology

[0002] Refractory molybdenum possesses advantages such as high thermal conductivity, good electrical conductivity, and thermal stability. Molybdenum sputtering targets are primarily used for thin-film transistors in TFT-LCD screens, enabling instantaneous control of individual image points (pixels) to ensure image quality. However, films sputtered from pure molybdenum targets suffer from corrosion resistance (discoloration) and adhesion (glass adhesion). By adding niobium to the molybdenum target, the specific impedance, stress, corrosion resistance, and other properties of the sputtered film can be balanced. Therefore, molybdenum-niobium (MoNb) is used for the highly corrosion-resistant ITO sensor metal wiring of touchscreens, exhibiting excellent performance. Molybdenum-niobium targets are a high-value-added and technically demanding deep-processed molybdenum product, and the rapid development of touchscreens has created a huge market demand and development space for molybdenum-niobium targets.

[0003] With increasingly fierce market competition, the quality requirements for MoNb alloy sputtering targets are becoming increasingly stringent. In sputtering applications, the quality of the target determines the sputtering efficiency and the performance of the thin film. To achieve high sputtering efficiency and ensure high-performance sputtered films, the target needs to meet high requirements such as high purity, high density, fine grain size, and uniform dimensions. Current technologies mainly employ melting and casting to prepare MoNb alloy targets. This involves melting the raw material, forming a column top in a mold, and then machining and rolling the ingot to improve the density and grain size of the MoNb target. However, casting MoNb targets requires high temperatures and sophisticated equipment, and the resulting target inevitably contains internal porosity, which negatively impacts the quality of the sputtered film. Therefore, there is an urgent need for a method to prepare MoNb alloy targets with high density, high purity, and fine, uniform grain structure. Summary of the Invention

[0004] The purpose of this invention is to provide a MoNb alloy target and its preparation method to solve the problem of poor performance of MoNb alloy targets in the prior art.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] In a first aspect, a method for preparing a MoNb alloy target includes the following steps:

[0007] Step 1: Mixing powders

[0008] Mo powder and Nb powder are added to a dual-motion powder mixing device at a ratio of 60-90%:10-40% and mixed in an inert atmosphere to obtain MoNb mixed powder.

[0009] Step 2, Pre-fire

[0010] MoNb mixed powder is filled into a mold and heated from room temperature (25-30℃) to 600-800℃ under vacuum conditions. After holding at this temperature for 1-2 hours, it is cooled to room temperature to obtain MoNb pre-calcined alloy powder.

[0011] Step 3, Package Setup

[0012] The pre-calcined MoNb alloy powder was packaged and packaged, and then degassed to obtain a degassed package.

[0013] Step 4: Hot isostatic pressing sintering

[0014] The degassed casing is placed in a hot isostatic pressing (HOP) sintering furnace and the temperature is gradually increased to the HOP sintering temperature of 1250-1400℃. At the same time, the pressure is uniformly increased to the HOP sintering pressure of 110-160MPa at a rate of 0.8-1.2MPa / min. After holding at the temperature for 3-5 hours, the pressure is recovered by cooling down the furnace to obtain the MoNb alloy target billet.

[0015] Step 5, Machining

[0016] After grinding the MoNb alloy target blank, a target material with qualified dimensions is obtained. Relevant defect and density tests are performed, and after no abnormalities are found, it is vacuum packaged.

[0017] Furthermore, in step 1, the motion frequency of the dual-motion powder mixing device is 30-50Hz, and the mixing time is 3-10h.

[0018] Furthermore, in step 1, the Mo powder has a purity of ≥99.95% and an average median diameter of 5-8 μm, and the Nb powder has a purity of ≥99.95% and an average median diameter of 30-45 μm.

[0019] Furthermore, in step 2, the heating rate is 10-15℃ / min, and the cooling rate is 2-4℃ / min.

[0020] Furthermore, in step 3, the outer layer material of the package is low-carbon steel or stainless steel, and graphite fiber paper is laid on the inner wall and bottom. Then, low-carbon steel partition and graphite fiber paper are laid on the bottom in sequence. MoNb pre-fired alloy powder is placed inside the package. Graphite fiber paper, low-carbon steel partition and graphite fiber paper are then placed on the MoNb pre-fired alloy powder in sequence. Finally, the package cover plate with degassing port is welded to the top of the package, and the degassing pipe is welded to the degassing port.

[0021] Furthermore, in step 3, the degassing process first involves using a helium mass spectrometer to check for leaks in the casing. If the leak is detected, degassing is performed by raising the temperature to 350-550℃ for 3-6 hours, until the vacuum level inside the casing is <4×10⁻⁶. -3 After Pa, the degassing tube near the sheath is flattened and the excess part is cut off to create a sealed vacuum environment inside the sheath.

[0022] Furthermore, in step 4, the gradient heating to isostatic pressing sintering specifically involves: after evacuating to <1000Pa, heating to 500-700℃ for the first time, and then heating to the hot isostatic pressing sintering temperature of 1250-1400℃ for the second time under an inert atmosphere.

[0023] Furthermore, the first heating rate is 2-4℃ / min; the second heating rate is 6-10℃ / min.

[0024] Furthermore, in step 4, the furnace is cooled to <100℃ and the pressure is recovered to 0MPa to meet the furnace discharge standard.

[0025] Furthermore, in step 5, the feed rate of the grinding machine is 2-10 μm per pass, and the wire EDM feed rate is 2-5 mm / min.

[0026] Furthermore, the inert atmosphere is either argon or nitrogen.

[0027] Secondly, a MoNb alloy target material is prepared by the above-mentioned preparation method.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] 1. This invention provides a method for preparing MoNb alloy targets using hot isostatic pressing (HIP). Compared to the uneven pressure distribution and insufficient density that occur in unidirectional pressure sintering, the HIP method allows the MoNb alloy powder to undergo isotropic pressure during heating. The combined effect of high temperature and high pressure promotes the densification of the metal alloy powder, which can significantly improve its density and performance while ensuring the purity of the metal alloy powder. The prepared MoNb alloy target has high density, is not prone to cracking, has high purity, and has a uniform microstructure, fine and uniform grains, good electrical conductivity, and excellent sputtering performance.

[0030] 2. This invention employs a dual-motion powder mixing stage, achieving highly efficient mixing at both the macroscopic and microscopic levels through the rotation of the mixing drum and the independent rotation of the built-in full-size blades. This mixing method is faster than traditional ball milling, significantly reducing mixing time, typically saving more than 50% of the mixing time compared to conventional equipment. Furthermore, it thoroughly shears and penetrates powder particles at the microscopic level, achieving extremely high mixing uniformity. This ensures that the mixed powder is uniformly dispersed among the particles, avoiding segregation that may occur with traditional ball milling.

[0031] 3. After mixing the powders, the MoNb mixed powder is pre-calcined under vacuum. Since the dehydrogenation temperature of Nb powder is between 500-800℃, the removal of hydrogen is beneficial to the densification of the sample during sintering. In addition, since the actual size of niobium powder particles is nearly ten times that of molybdenum powder particles, the sintering differences between different particles will lead to inhomogeneity of the alloy target structure. Pre-calcination removes some of the hydrogen from the Nb powder, further improving the grain size of the alloy target. Furthermore, during hot isostatic pressing (HIP), the temperature is first increased to 500-700℃ under vacuum gradient to prevent simultaneous deformation of Mo and Nb during calcination. Then, inert gas is introduced to increase the heating rate to the sintering temperature. A second HIP is then applied to reduce deformation and sintering differences between different particles, thereby improving grain fineness and preventing cracking of the MoNb alloy target. Attached Figure Description

[0032] The present invention will now be further described with reference to the accompanying drawings.

[0033] Figure 1 This is a schematic diagram of the preparation process of a MoNb alloy target according to the present invention;

[0034] Figure 2 This is a schematic diagram of the packaging assembly structure during the packaging process in step 3 of the present invention;

[0035] Figure 3 This is a physical image of the MoNb alloy target material prepared in Example 1 of the present invention. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0037] Please see Figure 1 A method for preparing a MoNb alloy target includes the following steps:

[0038] Step 1: Mixing powders

[0039] Mo powder with a purity ≥99.95% and an average median diameter of 5-8 μm, and Nb powder with a purity ≥99.95% and an average median diameter of 30-45 μm, were weighed at a ratio of 60-90%:10-40%.

[0040] The powder is added to a dual-motion powder mixing device and mixed in an inert atmosphere. The mixing motion frequency is 30-50Hz and the mixing time is 3-10h to obtain MoNb mixed powder.

[0041] Step 2, Pre-fire

[0042] MoNb mixed powder is filled into a mold and heated to 600-800℃ from room temperature at a heating rate of 10-15℃ / min under vacuum conditions. After holding at this temperature for 1-2 hours, it is cooled to room temperature at a cooling rate of 2-4℃ / min to obtain MoNb pre-calcined alloy powder.

[0043] Step 3, Package Setup

[0044] The bag is designed according to the finished product dimensions. A bag assembly diagram is shown below. Figure 2 As shown, Figure 2 In the process, the outer layer of the package is made of low-carbon steel or stainless steel. Graphite fiber paper is laid on the inner wall and bottom. Then, low-carbon steel partition and graphite fiber paper are laid on the bottom in sequence. MoNb pre-fired alloy powder is placed inside the package. Graphite fiber paper, low-carbon steel partition and graphite fiber paper are then placed on the MoNb pre-fired alloy powder in sequence. Finally, the package cover plate with degassing port is welded to the top of the package, and the degassing pipe is welded to the degassing port.

[0045] After encapsulation, degassing is performed, and the encapsulation is leak-tested using a helium mass spectrometer. Once the leak is confirmed to be normal, degassing is carried out at a temperature of 350-550℃ for 3-6 hours, until the vacuum level inside the encapsulation is <4×10⁻⁶. -3 After Pa, the degassing tube near the sheath is flattened and the excess part is cut off to create a sealed vacuum environment inside the sheath.

[0046] Step 4: Hot isostatic pressing sintering

[0047] The degassed casing is placed in a hot isostatic pressing (HOP) sintering furnace, and the vacuum is evacuated to <1000 Pa. The temperature is first increased to 500-700 °C at a rate of 2-4 °C / min, and then increased a second time at a rate of 6-10 °C / min under an inert atmosphere. The temperature is gradually increased to the HOP sintering temperature of 1250-1400 °C. While the temperature is increasing, the pressure is uniformly increased at a rate of 0.8-1.5 MPa / min to the HOP sintering pressure of 110-160 MPa. The furnace is held at this temperature for 3-5 hours. After sintering, the furnace is cooled and the pressure is recovered until the temperature is <100 °C and the pressure in the HOP sintering furnace is 0 MPa. The furnace is then ready for the MoNb alloy target billet.

[0048] Step 5, Machining

[0049] After grinding the MoNb alloy target blank, a target material with qualified dimensions is obtained. Relevant defect and density tests are performed, and after no abnormalities are found, it is vacuum packaged.

[0050] After removing the outer sheath of the MoNb alloy target blank, it is ground according to the drawing requirements. The feed rate of the grinding machine is 2-10μm per pass, and the wire EDM feed rate is 2-5mm / min. The outer circle is then machined to obtain a target blank with qualified dimensions. Relevant defect and density tests are performed. After no abnormalities are found, it is vacuum-packed to obtain the finished MoNb alloy target material.

[0051] Example 1

[0052] Please see Figure 1 A method for preparing a MoNb alloy target includes the following steps:

[0053] Step 1: Mixing powders

[0054] Mo powder with a purity ≥99.95% and an average median diameter of 5-8 μm, and Nb powder with a purity ≥99.95% and an average median diameter of 30-45 μm, were weighed in a ratio of 80%:20%.

[0055] The powder was added to a dual-motion powder mixing device and mixed in an argon atmosphere. The mixing motion frequency was 40 Hz and the mixing time was 8 h to obtain MoNb mixed powder.

[0056] Step 2, Pre-fire

[0057] MoNb mixed powder was filled into a mold and heated to 700°C from room temperature at a heating rate of 12°C / min under vacuum conditions. After holding at this temperature for 1.5 hours, it was cooled to room temperature at a cooling rate of 3°C / min to obtain MoNb pre-calcined alloy powder.

[0058] Step 3, Package Setup

[0059] The bag is designed according to the finished product dimensions. A bag assembly diagram is shown below. Figure 2 As shown, Figure 2 In the process, the outer layer of the package is made of low-carbon steel or stainless steel. Graphite fiber paper is laid on the inner wall and bottom. Then, low-carbon steel partition and graphite fiber paper are laid on the bottom in sequence. MoNb pre-fired alloy powder is placed inside the package. Graphite fiber paper, low-carbon steel partition and graphite fiber paper are then placed on the MoNb pre-fired alloy powder in sequence. Finally, the package cover plate with degassing port is welded to the top of the package, and the degassing pipe is welded to the degassing port.

[0060] After encapsulation, degassing is performed, and the encapsulation is leak-tested using a helium mass spectrometer. Once the leak is confirmed, degassing is carried out at 450℃ for 5 hours, until the internal vacuum of the encapsulation reaches 3×10⁻⁶. -3 After Pa, the degassing tube near the sheath is flattened and the excess part is cut off to create a sealed vacuum environment inside the sheath.

[0061] Step 4: Hot isostatic pressing sintering

[0062] The degassed casing is placed in a hot isostatic pressing (HOP) sintering furnace, and the vacuum is reduced to <1000 Pa. The temperature is first increased to 600 °C at a rate of 3 °C / min, and then increased a second time at a rate of 8 °C / min under an argon atmosphere. The temperature is gradually increased to the HOP sintering temperature of 1300 °C. Simultaneously, the pressure is uniformly increased at a rate of 1.2 MPa / min to the HOP sintering pressure of 140 MPa. The furnace is held at this temperature for 4 hours. After sintering, the furnace is cooled and the pressure is recovered until the temperature is <100 °C and the pressure in the HOP sintering furnace is 0 MPa. The furnace is then ready for annealing, and the MoNb alloy target billet is obtained.

[0063] Step 5, Machining

[0064] After grinding the MoNb alloy target blank, a target material with qualified dimensions is obtained. Relevant defect and density tests are performed, and after no abnormalities are found, it is vacuum packaged.

[0065] After removing the outer sheath of the MoNb alloy target blank, it was ground according to the drawing requirements. The grinding depth per pass was 6μm, and the wire EDM feed rate was 3mm / min. The outer diameter was then machined to obtain a target blank with acceptable dimensions. Relevant defect and density tests were performed. After confirming no abnormalities, it was vacuum-packed to obtain the finished MoNb alloy target material. A picture of the actual product is shown below. Figure 3 As shown.

[0066] Example 2

[0067] A method for preparing a MoNb alloy target differs from Example 1 in that, in step 4, the hot isostatic pressing sintering temperature is 1400℃, the pressure is 120MPa, and the sintering time is 4h, while the remaining steps and parameters remain the same.

[0068] Example 3

[0069] A method for preparing a MoNb alloy target material differs from Example 1 in that, in step 4, the hot isostatic pressing sintering temperature is 1250℃, the pressure is 160MPa, and the sintering time is 5h, while the remaining steps and parameters remain the same.

[0070] Comparative Example 1

[0071] A method for preparing a MoNb alloy target material differs from Example 1 in that, in step 4, the hot isostatic pressing sintering temperature is 1650℃, while the remaining steps and parameters remain the same.

[0072] Comparative Example 2

[0073] A method for preparing a MoNb alloy target differs from Example 1 in that, in step 4, the hot isostatic pressing sintering pressure is 40°C, while the remaining steps and parameters remain the same.

[0074] Comparative Example 3

[0075] A method for preparing a MoNb alloy target differs from Example 1 in that step 2 (pre-sintering) is omitted, and the MoNb mixed powder is directly packaged and then subjected to hot isostatic pressing sintering and other processes, while maintaining the same process parameters.

[0076] Comparative Example 4

[0077] A method for preparing a MoNb alloy target material differs from Example 1 in that step 4 employs a direct heating method, and the hot isostatic pressing sintering is specifically as follows:

[0078] The degassed casing is placed in a hot isostatic pressing (HOP) sintering furnace, and the vacuum is evacuated to <1000Pa. The temperature is increased to the HOP sintering temperature of 1300℃ at a rate of 8℃ / min. At the same time, the pressure is increased at a uniform rate to the HOP sintering pressure of 140MPa. The furnace is held at this temperature for 4 hours. After sintering, the furnace is cooled and the pressure is recovered until the temperature is <100℃ and the pressure in the HOP sintering furnace is 0MPa. The furnace is then ready to be unloaded and the MoNb alloy target billet is obtained.

[0079] The remaining steps and parameters remain the same.

[0080] Comparative Example 5

[0081] A method for preparing a MoNb alloy target differs from Example 1 in that step 2 (pre-sintering) is omitted, and step 4 involves direct heating. The specific hot isostatic pressing sintering process is the same as that in Comparative Example 4.

[0082] The performance of the MoNb alloy targets prepared in Examples 1-3 and Comparative Examples 1-5 was tested:

[0083] Density was determined using the traditional Archimedes method and calculated using (tested density ÷ theoretical density) × 100%. Microstructure analysis was performed and the average grain size of Mo and Nb was calculated using the intercept method. Purity was determined using GDMS.

[0084] The test results are shown in Table 1.

[0085] Table 1

[0086] Density (%) Average grain size (μm) purity(%) Example 1 99.9 25 ＞99.95 Example 2 99.4 31 ＞99.95 Example 3 99.6 28 ＞99.95 Comparative Example 1 98.1 38 ＜99.95 Comparative Example 2 97.6 35 ＜99.95 Comparative Example 3 94.2 42 ＜99.95 Comparative Example 4 95.8 47 ＜99.95 Comparative Example 5 90.3 63 ＜99.95

[0087] As shown in Table 1, the present invention first employs a pre-sintering method, which causes sliding and breakage between larger niobium powder particles, thereby achieving dehydrogenation of niobium powder and removal of surface particulate contaminants. This increases the metal contact area between particles and improves the density of the alloy target. During the hot isostatic pressing sintering process, new crystals, i.e., recrystallization, are generated during high-temperature calcination. To prevent abnormal grain growth during sintering, a gradient heating method is used to increase the strength of the alloy particles, thereby increasing the density. Then, relying on grain boundary diffusion and flow, continuous hot pressing densification leads to the shrinkage of pores, increasing the stress at the pores, and causing the pores to shrink into a large number of closed pores, reaching the ultimate density. The resulting MoNb alloy target has high density, small average grain size, and higher purity.

[0088] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0089] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a MoNb alloy target, characterized in that, Includes the following steps: Step 1: Add Mo powder and Nb powder to a dual-motion powder mixing device at a ratio of 60-90%:10-40% and mix the powders in an inert atmosphere to obtain MoNb mixed powder. Step 2: Fill the mold with the MoNb mixed powder, heat it from room temperature to 600-800℃ under vacuum conditions, hold it at that temperature for 1-2 hours and then cool it down to room temperature to obtain MoNb pre-calcined alloy powder. Step 3: Pack the MoNb pre-calcined alloy powder according to the packaging package, and then degas it to obtain a degassed package. Step 4: Place the degassed cladding into a hot isostatic pressing (HOP) sintering furnace and gradually increase the temperature to the HOP sintering temperature of 1250-1400℃. Simultaneously, increase the pressure at a constant rate of 0.8-1.2 MPa / min to the HOP sintering pressure of 110-160 MPa. After holding the sintering temperature for 3-5 hours, cool down the furnace and recover the pressure to obtain the MoNb alloy target billet. Step 5: After grinding the MoNb alloy target blank, a target material with qualified dimensions is obtained. Relevant defect and density tests are performed. After no abnormalities are found, it is vacuum-packed. In step 4, the gradient heating to isostatic pressing sintering is specifically as follows: after evacuating to <1000Pa, the temperature is first raised to 500-700℃, and then, under an inert atmosphere, the temperature is raised a second time to the hot isostatic pressing sintering temperature of 1250-1400℃. The first heating rate is 2-4℃ / min; the second heating rate is 6-10℃ / min.

2. The method for preparing a MoNb alloy target according to claim 1, characterized in that, In step 1, the motion frequency of the dual-motion powder mixing device is 30-50Hz, and the mixing time is 3-10h.

3. The method for preparing a MoNb alloy target according to claim 1, characterized in that, In step 1, the Mo powder has a purity of ≥99.95% and an average median diameter of 5-8 μm, and the Nb powder has a purity of ≥99.95% and an average median diameter of 30-45 μm.

4. The method for preparing a MoNb alloy target according to claim 1, characterized in that, In step 2, the heating rate is 10-15℃ / min and the cooling rate is 2-4℃ / min.

5. The method for preparing a MoNb alloy target according to claim 1, characterized in that, In step 3, the degassing process begins with a helium mass spectrometer leak detector to check for leaks in the casing. If the leak is detected, degassing is initiated by heating. The degassing temperature is 350-550℃, and the degassing time is 3-6 hours, until the vacuum degree inside the casing is <4×10⁻⁶. -3 After Pa, the degassing tube near the sheath is flattened and the excess part is cut off to create a sealed vacuum environment inside the sheath.

6. The method for preparing a MoNb alloy target according to claim 1, characterized in that, In step 4, the furnace temperature is lowered to <100℃ and the pressure is recovered to 0MPa to meet the furnace discharge standard.

7. The method for preparing a MoNb alloy target according to claim 1, characterized in that, In step 5, the feed rate of the grinding machine is 2-10 μm per pass, and the wire EDM feed rate is 2-5 mm / min.

8. A MoNb alloy target material, characterized in that, It is prepared by any one of the preparation methods of claims 1-7.

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