MoNb alloy target material and preparation method thereof

Abstract

The invention discloses a MoNb alloy target material and a preparation method thereof, and belongs to the technical field of target material preparation. Comprising the following steps that Mo powder and Nb powder are mixed in an inert atmosphere, and MoNb mixed powder is obtained; placing under a vacuum condition, and pre-sintering to obtain MoNb pre-sintered alloy powder; sheathing the MoNb pre-sintered alloy powder according to sheathing assembly, degassing, putting into a hot isostatic pressing sintering furnace, carrying out gradient heating to 1250-1400 DEG C, increasing the pressure to 110-160 MPa at a constant speed while heating, carrying out heat preservation calcination for 3-5 hours, cooling along with the furnace, and recovering the pressure to obtain a MoNb alloy target blank; and the MoNb alloy target blank is machined through a grinding machine, and then the MoNb alloy target with the qualified size is obtained. The prepared MoNb alloy target material is high in density, not prone to cracking, high in purity, uniform and fine in grain structure, good in conductivity and excellent in sputtering performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of target material preparation, and in particular relates to a MoNb alloy target material and a preparation method thereof. Background Art

[0002] The refractory metal molybdenum has the advantages of high thermal conductivity, good electrical conductivity and thermal stability. Molybdenum target sputtered films are mainly used in thin film transistors of TFT-LCD screens, which can instantly control individual image points (pixels), thereby ensuring the image quality of the display screen. However, the films sputtered from pure molybdenum targets have problems in corrosion resistance (discoloration) and adhesion (film glass). By adding niobium elements to the molybdenum target, the various properties of the sputtered film, such as specific impedance, stress, and corrosion resistance, can be balanced. Therefore, molybdenum niobium (MoNb) is used for extremely corrosion-resistant touch screen ITO sensor metal wiring, showing excellent performance. Molybdenum niobium target is a molybdenum deep-processing product with high added value and technical requirements. The rapid development of touch screens has created huge market demand and development space for molybdenum niobium targets.

[0003] As market competition becomes increasingly fierce, the quality requirements for MoNb alloy targets are getting higher and higher. In the application of target materials, the quality of the target material determines the efficiency of sputtering and the performance of the film. In order to achieve high sputtering efficiency and ensure that a sputtering film with excellent performance is obtained, the target material needs to meet high requirements such as high purity, high density, fine grains, and uniform size. In the prior art, MoNb alloy targets are mainly prepared by smelting and casting. After the raw materials are melted, a column top is formed in a mold, and then the ingot is mechanically processed and rolled to improve the density and grain size of the MoNb target. However, the temperature required for casting to prepare MoNb targets is relatively high, and the equipment requirements are high. In addition, it is difficult to avoid pores inside the material in the formed target material, which has a certain impact on the quality of the sputtering film. Therefore, there is an urgent need for a method for preparing a MoNb alloy target material to prepare a MoNb alloy target material with high density, high purity, and fine and uniform grain structure. Summary of the Invention

[0004] The object of the present invention is to provide a MoNb alloy target and a preparation method thereof, so as to solve the problem of poor performance of MoNb alloy targets in the prior art.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

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

[0007] Step 1: Mix powder

[0008] Adding Mo powder and Nb powder in a ratio of 60-90%:10-40% into a double motion powder mixing device, mixing the powders in an inert atmosphere to obtain MoNb mixed powder;

[0009] Step 2: Pre-burn

[0010] The MoNb mixed powder is filled into a mold, and heated from room temperature (25-30°C) to 600-800°C under vacuum conditions, kept at this temperature for 1-2 hours, and then cooled to room temperature to obtain MoNb pre-sintered alloy powder;

[0011] Step 3: Packaging Assembly

[0012] The MoNb pre-sintered alloy powder is encapsulated according to the encapsulation preparation, and then degassed to obtain a degassed encapsulation;

[0013] Step 4: Hot isostatic pressing

[0014] The degassed package is placed in a hot isostatic pressing furnace, and the temperature is gradually increased to a hot isostatic pressing sintering temperature of 1250-1400°C. While the temperature is increased, the pressure is uniformly increased at a rate of 0.8-1.2 MPa / min to a hot isostatic pressing sintering pressure of 110-160 MPa. After calcining for 3-5 hours, the temperature is lowered and the pressure is recovered to obtain a MoNb alloy target blank.

[0015] Step 5: Machining

[0016] The MoNb alloy target blank is grinded to obtain target materials with qualified size, and then subjected to relevant defect and density tests. If no abnormality is found, the target materials are vacuum packaged.

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

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

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

[0020] Furthermore, in step 3, the outer layer material of the package assembly is low carbon steel or stainless steel, graphite fiber paper is laid on the inner wall and bottom, and then a low carbon steel partition and graphite fiber paper are laid on the bottom in sequence, the MoNb pre-sintered alloy powder is placed in the package, and graphite fiber paper, low carbon steel partition and graphite fiber paper are placed on the MoNb pre-sintered alloy powder in sequence. Finally, the package cover with a 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 uses a helium mass spectrometer to detect leaks on the package, and then degassing is carried out by heating; the degassing temperature is 350-550 ° C, the degassing time is 3-6 hours, and the vacuum degree inside the package is less than 4×10 -3 After Pa, the degassing tube near the package is flattened and the excess part is cut off to form a closed vacuum environment inside the package.

[0022] Furthermore, in step 4, the gradient temperature increase to isostatic pressing sintering is specifically as follows: after evacuating to <1000 Pa, the temperature is increased to 500-700°C for the first time, and then in an inert atmosphere, the temperature is increased to the hot isostatic pressing sintering temperature of 1250-1400°C for the second time.

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

[0024] Furthermore, in step 4, the temperature is lowered to <100° C. with the furnace, and the pressure is recovered to 0 MPa to meet the furnace discharge standard.

[0025] Furthermore, in step 5, the feed rate of the grinding machine is 2-10 μm, and the wire cutting speed of the electric spark wire cutting is 2-5 mm / min.

[0026] Furthermore, the inert atmosphere is any one of argon and nitrogen.

[0027] In a second aspect, a MoNb alloy target is prepared by the above preparation method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention provides a method for preparing a MoNb alloy target by hot isostatic pressing. Compared with the problems of uneven pressure distribution and insufficient density in the green body caused by unidirectional pressure sintering, the MoNb alloy target is sintered by hot isostatic pressing, so that the MoNb alloy powder is subjected to isotropic pressure during the heating process. The combined effect of high temperature and high pressure promotes the densification of the metal alloy powder, which can significantly improve the density and performance of the metal alloy powder while ensuring the purity of the metal alloy powder. The prepared MoNb alloy target has high density, is not easy to crack, has high purity, and has a uniform microstructure, uniform and fine grains, good electrical conductivity, and excellent sputtering performance.

[0030] 2. This invention utilizes dual-motion powder mixing during the mixing stage. This achieves efficient mixing at both the macro and micro levels through the rotating barrel and the independent rotation of built-in, full-size blades. This mixing method is much faster than traditional ball milling and significantly reduces mixing time, typically saving over 50% compared to traditional equipment. Furthermore, powder particles are fully sheared and interpenetrated at the microscopic level, achieving extremely high mixing uniformity. This ensures uniform dispersion of the mixed powder between particles, avoiding the potential for segregation associated with traditional ball milling.

[0031] 3. After mixing, the MoNb mixed powder is vacuum pre-sintered. Since the dehydrogenation temperature of Nb powder is between 500-800°C, 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 uneven structure of the alloy target. Pre-sintering is used to remove some hydrogen from the Nb powder, further improving the grain size of the alloy target. In addition, during the hot isostatic pressing process, the temperature is first increased to 500-700°C in a vacuum gradient to avoid simultaneous deformation of Mo and Nb during the calcination process. Then, inert gas is introduced and the heating rate is increased to the sintering temperature. The same hot isostatic pressing sintering is performed again to reduce the deformation and sintering differences between different particles, thereby improving the grain fineness and avoiding cracking of the MoNb alloy target. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

[0035] Figure 3 This is a physical picture of the MoNb alloy target prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] See also Figure 1 A method for preparing a MoNb alloy target comprises the following steps:

[0038] Step 1: Mix powder

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

[0040] Add the powder to a dual-motion powder mixing device and mix the powder in an inert atmosphere at a mixing frequency of 30-50 Hz for 3-10 hours to obtain a MoNb mixed powder;

[0041] Step 2: Pre-burn

[0042] The MoNb mixed powder is filled into a mold, and heated from room temperature to 600-800°C at a heating rate of 10-15°C / min under vacuum conditions, kept at this temperature for 1-2 hours, and then cooled to room temperature at a cooling rate of 2-4°C / min to obtain MoNb pre-sintered alloy powder;

[0043] Step 3: Packaging Assembly

[0044] Design the package according to the size of the finished product. The package assembly diagram is as follows Figure 2 As shown, Figure 2 In the process, the outer layer of the package assembly is made of low-carbon steel or stainless steel, graphite fiber paper is laid on the inner wall and bottom, and then a low-carbon steel separator and graphite fiber paper are laid on the bottom in sequence. MoNb pre-sintered alloy powder is placed in the package, and graphite fiber paper, low-carbon steel separator and graphite fiber paper are placed on the MoNb pre-sintered alloy powder in sequence. Finally, the package cover with a degassing port is welded to the top of the package, and the degassing pipe is welded to the degassing port.

[0045] After the package is wrapped, it is degassed and the package is leak tested with a helium mass spectrometer. After the leak test is OK, the package is heated for degassing at a temperature of 350-550°C and a degassing time of 3-6 hours. When the vacuum degree inside the package is less than 4×10 -3 After Pa, the degassing tube near the package is flattened and the excess part is cut off to form a closed vacuum environment inside the package;

[0046] Step 4: Hot isostatic pressing

[0047] The degassed package is placed in a hot isostatic pressing furnace, evacuated to <1000Pa, and heated to 500-700°C at a rate of 2-4°C / min for the first time. Then, under an inert atmosphere, the temperature is increased for the second time at a rate of 6-10°C / min to a sintering temperature of 1250-1400°C for isostatic pressing. While heating, the pressure is uniformly increased at a rate of 0.8-1.5MPa / min to a hot isostatic pressing pressure of 110-160MPa. The package is kept at this temperature for 3-5h. After sintering, the temperature is lowered and the pressure is recovered along with the furnace until the temperature is <100°C and the pressure of the hot isostatic pressing furnace is 0MPa, and the MoNb alloy target blank meets the furnace discharge standard to obtain the target.

[0048] Step 5: Machining

[0049] The MoNb alloy target blank is grinded to obtain target materials with qualified size, and then subjected to relevant defect and density tests. If no abnormality is found, the target materials are vacuum packaged.

[0050] The outer sheath of the MoNb alloy target blank is removed, and the target blank is grinded according to the drawing requirements. The feed amount of the grinder is 2-10μm, and the wire cutting speed of the electric spark wire cutting is 2-5mm / min. The outer circle is then processed to obtain a target blank with qualified size. Relevant defect and density tests are carried out. If no abnormalities are found, the target blank is vacuum packaged to obtain a finished MoNb alloy target.

[0051] Example 1

[0052] See also Figure 1 A method for preparing a MoNb alloy target comprises the following steps:

[0053] Step 1: Mix powder

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

[0055] Add the powder to a dual-motion powder mixing device and mix the powder in an argon atmosphere at a mixing frequency of 40 Hz for 8 hours to obtain a MoNb mixed powder;

[0056] Step 2: Pre-burn

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

[0058] Step 3: Packaging Assembly

[0059] Design the package according to the size of the finished product. The package assembly diagram is as follows Figure 2 As shown, Figure 2 In the process, the outer layer of the package assembly is made of low-carbon steel or stainless steel, graphite fiber paper is laid on the inner wall and bottom, and then a low-carbon steel separator and graphite fiber paper are laid on the bottom in sequence. MoNb pre-sintered alloy powder is placed in the package, and graphite fiber paper, low-carbon steel separator and graphite fiber paper are placed on the MoNb pre-sintered alloy powder in sequence. Finally, the package cover with a degassing port is welded to the top of the package, and the degassing pipe is welded to the degassing port.

[0060] After the package is wrapped, it is degassed and the package is leak-tested with a helium mass spectrometer. After the leak is detected, the package is heated for degassing at a temperature of 450 ° C and a degassing time of 5 hours. When the vacuum degree inside the package is 3×10 -3 After Pa, the degassing tube near the package is flattened and the excess part is cut off to form a closed vacuum environment inside the package;

[0061] Step 4: Hot isostatic pressing

[0062] The degassed package is placed in a hot isostatic pressing furnace, evacuated to <1000Pa, and heated to 600°C at a rate of 3°C / min for the first time. Then, in an argon atmosphere, the temperature is increased for the second time at a rate of 8°C / min to an isostatic pressing sintering temperature of 1300°C by gradient heating. While heating, the pressure is uniformly increased at a rate of 1.2MPa / min to a hot isostatic pressing pressure of 140MPa. The target is kept at this temperature and calcined for 4h. After sintering, the target is cooled and the pressure is recovered with the furnace until the temperature is <100°C and the pressure of the hot isostatic pressing furnace is 0MPa, meeting the furnace discharge standard to obtain a MoNb alloy target blank.

[0063] Step 5: Machining

[0064] The MoNb alloy target blank is grinded to obtain target materials with qualified size, and then subjected to relevant defect and density tests. If no abnormality is found, the target materials are vacuum packaged.

[0065] The outer sheath of the MoNb alloy target blank is removed and the target blank is ground according to the drawing requirements. The feed rate of the grinding machine is 6μm and the wire cutting speed of the electric spark wire cutting is 3mm / min. The outer circle is then processed to obtain a target blank with qualified size. The target blank is tested for relevant defects and density. If no abnormality is found, it is vacuum packed to obtain the finished MoNb alloy target. The actual picture is as follows Figure 3 shown.

[0066] Example 2

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

[0068] Example 3

[0069] A method for preparing a MoNb alloy target is different from that of Example 1 in that, in step 4, the hot isostatic pressing sintering temperature is 1250° C., the pressure is 160 MPa, and the sintering time is 5 h, and the other steps and parameters remain the same.

[0070] Comparative Example 1

[0071] A method for preparing a MoNb alloy target is different from that of Example 1 in that, in step 4, the temperature of hot isostatic pressing sintering is 1650° C., and the other steps and parameters remain the same.

[0072] Comparative Example 2

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

[0074] Comparative Example 3

[0075] A method for preparing a MoNb alloy target material differs from that of Example 1 in that the pre-sintering process in step 2 is not performed, and the MoNb mixed powder is directly subjected to packaging assembly and subsequent hot isostatic pressing and sintering processes, and the process parameters remain consistent.

[0076] Comparative Example 4

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

[0078] The degassed package is placed in a hot isostatic pressing furnace, vacuumed to <1000 Pa, heated to an isostatic pressing temperature of 1300° C. at a rate of 8° C. / min, and simultaneously heated to a hot isostatic pressing pressure of 140 MPa. The package is kept at this temperature for 4 hours. After sintering, the package is cooled and the pressure is recovered until the temperature is <100° C. and the pressure of the hot isostatic pressing furnace is 0 MPa. The MoNb alloy target blank is then discharged from the furnace and the discharge standard is obtained.

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

[0080] Comparative Example 5

[0081] A method for preparing a MoNb alloy target material is different from Example 1 in that the pre-sintering process in step 2 is not performed, and step 4 adopts direct heating. The specific process of hot isostatic pressing sintering is the same as that of Comparative Example 4.

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

[0083] The density was tested using the traditional Archimedean method and calculated using (test density ÷ theoretical density) × 100%. The average grain size of Mo and Nb was calculated using the intercept method for microstructural analysis. The purity was tested 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 can be seen from Table 1, the present invention first adopts a pre-sintering method to cause sliding and breaking between larger niobium powder particles, thereby achieving dehydrogenation of the niobium powder and removal of surface particle contaminants, increasing the metal contact area between the particles, and improving the density of the alloy target. During the hot isostatic pressing sintering process, new crystallization, namely recrystallization, will be generated during the high-temperature calcination process. In order to prevent abnormal growth of grains during the sintering process, a gradient temperature increase is adopted to improve the strength of the alloy particles and increase the density. Then, relying on grain boundary diffusion and flow, as the hot pressing densification continues, the pores are reduced, the stress at the pores increases, and the pores 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, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "includes," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

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

Claims

1. A method for preparing a MoNb alloy target, characterized in that: The following steps are involved: Step 1, adding Mo powder and Nb powder in a ratio of 60-90%:10-40% into a double motion powder mixing device, mixing the powders in an inert atmosphere to obtain MoNb mixed powder; Step 2, filling the MoNb mixed powder into a mold, heating from room temperature to 600-800°C under vacuum conditions, calcining for 1-2 hours and then cooling to room temperature to obtain MoNb pre-sintered alloy powder; Step 3, encapsulating the MoNb pre-sintered alloy powder according to the encapsulation preparation, and performing a degassing treatment after encapsulation to obtain a degassed encapsulation; Step 4, placing the degassed package into a hot isostatic pressing furnace, gradually heating the temperature to an isostatic pressing temperature of 1250-1400°C, while heating, uniformly increasing the pressure to a hot isostatic pressing pressure of 110-160MPa at a rate of 0.8-1.2MPa / min, calcining for 3-5h, cooling and recovering the pressure with the furnace, and obtaining a MoNb alloy target blank; Step 5: Grind the MoNb alloy target blank to obtain a target material with qualified size, conduct relevant defect and density tests, and vacuum pack it if no abnormality is found.

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

3. The method for preparing a MoNb alloy target according to claim 1, characterized in that: In step 1, the purity of the Mo powder is ≥99.95%, and the average median diameter is 5-8 μm; the purity of the Nb powder is ≥99.95%, and the average median diameter is 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°C / min, and the cooling rate is 2-4°C / min.

5. The method for preparing a MoNb alloy target according to claim 1, characterized in that: In step 3, the degassing process first uses a helium mass spectrometer to detect leaks on the package, and then degassing is performed by heating; the degassing temperature is 350-550°C, the degassing time is 3-6h, and the vacuum degree inside the package is less than 4×10 -3 After Pa, the degassing tube near the package is flattened and the excess part is cut off to form a closed vacuum environment in the package.

6. The method for preparing a MoNb alloy target according to claim 1, characterized in that: In step 4, the temperature is gradually increased to isostatic pressing sintering by: after evacuating to less than 1000 Pa, the temperature is increased to 500-700° C. for the first time, and then the temperature is increased to the hot isostatic pressing sintering temperature of 1250-1400° C. for the second time under an inert atmosphere.

7. The method for preparing a MoNb alloy target according to claim 6, characterized in that: The first heating rate is 2-4°C / min; the second heating rate is 6-10°C / min.

8. 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°C and the pressure is recovered to 0 MPa to meet the furnace discharge standard.

9. The method for preparing a MoNb alloy target according to claim 1, characterized in that: In step 5, the feed amount of the grinder is 2-10 μm, and the wire cutting rate of the electric spark wire cutting is 2-5 mm / min.

10. A MoNb alloy target, characterized in that: Prepared by any one of the preparation methods of claim 1 to claim 9.

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