A silicide target and a method of manufacturing the same

Abstract

The application provides a silicide target and a preparation method thereof, relates to the technical field of high-performance silicide target preparation, and the preparation method of the silicide target comprises the following steps: forming a surface dense layer on both sides of a refractory metal silicide pre-compacted body through plastic deformation treatment to obtain a modified pre-compacted body; laying a first refractory metal foil in a mold cavity, laying a first hexagonal boron nitride powder layer on the first refractory metal foil, placing one side of the surface dense layer of the modified pre-compacted body on the first hexagonal boron nitride powder layer, and sequentially laying a second hexagonal boron nitride powder layer and a second refractory metal foil on the other side of the surface dense layer of the modified pre-compacted body, and then performing hot-pressing sintering. The preparation method provided by the application can meet the dual requirements of efficient carbon blocking and flexible buffering under hot-pressing sintering, and thus the product purity and the yield of finished products are improved.

Description

Technical Field

[0001] This invention relates to the field of high-performance silicide target preparation technology, and in particular to a silicide target and its preparation method. Background Technology

[0002] In the hot-pressing sintering process of refractory metal silicides (such as tungsten-silicon alloys and molybdenum-silicon alloys), the workpiece typically needs to be placed in a graphite mold for high-temperature forming and densification. However, this process has long faced two key technical challenges: first, the graphite mold can carburize into the workpiece at high temperatures, leading to excessive carbon content in the material and severely affecting the purity of the final product; second, during cooling, due to the direct contact between the graphite mold and the workpiece and the significant difference in their coefficients of thermal expansion, significant shear stress is generated at the interface. This interfacial stress easily causes the brittle metal silicide preform to crack at the edges or adhere to the mold, resulting in product scrap. Various attempts have been made both domestically and internationally to address these issues, mainly focusing on physical barriers and surface coatings, but these solutions all have significant limitations. For example: Patent application CN111763914A discloses a method for controlling the content of non-metallic elements in tungsten-silicon sputtering targets. This method uses oxygen-absorbing metal foil (such as titanium or tantalum foil) to isolate the blank from the graphite mold, thereby reducing the introduction of non-metallic elements such as carbon. While this method can block carbon diffusion to some extent, the metal foil itself is a rigid material and cannot effectively buffer thermal stress. Furthermore, at high temperatures, it may react with silicon to form silicides, introducing new risks of metal contamination.

[0003] In addition, common coating protection methods (such as coating the surface of graphite devices with a tungsten / molybdenum and silicon nitride / silicon oxide composite coating in CN105112995A, preparing silicon carbide or boron nitride coatings on the surface of crucible lids in CN211645445U, and using boron nitride spray to isolate molds in CN117819967A) can provide physical barriers, but they have inherent limitations in practical applications: the coating is difficult to prepare a thick and uniform cover layer due to process constraints, and it is easy to form microscopic pinhole defects, which become channels for carbon diffusion; at the same time, the adhesion between the coating and the graphite substrate is limited, and it is easy to peel off under thermal cycling stress, which not only loses the protective function, but the peeling material can also contaminate the workpiece; in addition, such coatings (such as silicon carbide prepared by chemical vapor deposition) have complex processes and high costs, which restricts their large-scale application.

[0004] In summary, most existing technologies focus on achieving a single function (carbon inhibition or stress relief) and mostly use rigid isolation materials, making it difficult to simultaneously meet the dual requirements of efficient carbon inhibition and flexible buffering at high temperatures, resulting in a tradeoff between product purity and yield. Summary of the Invention

[0005] This invention provides a silicide target and its preparation method to solve the defects in the prior art where, during the hot pressing sintering process of refractory metal silicides, the graphite mold will carburize into the workpiece at high temperature, resulting in excessive carbon content in the target material, and the interfacial stress will cause the brittle metal silicide blank to crack at the edge or stick to the mold. This invention achieves the dual requirements of efficient carbon inhibition and flexible buffering under hot pressing sintering, thereby improving product purity and yield.

[0006] In a first aspect, the present invention provides a method for preparing a silicide target, comprising the following steps: S1. The two sides of the refractory metal silicide pre-compressed billet are plastically deformed to form a dense surface layer, thus obtaining a modified pre-compressed billet; S2. A first refractory metal foil is laid in the mold cavity, and a first hexagonal boron nitride powder layer is laid on the first refractory metal foil. The surface dense layer of the modified pre-pressed billet is placed on the first hexagonal boron nitride powder layer, and a second hexagonal boron nitride powder layer and a second refractory metal foil are sequentially laid on the surface dense layer on the other side of the modified pre-pressed billet. The mixture is then hot-pressed and sintered to obtain a silicide target.

[0007] This invention provides a method for preparing a silicide target. On one hand, a surface densification treatment is performed on both sides of the refractory metal silicide blank, forming a dense layer on both sides of the blank. This dense layer has a higher relative density than the blank body and extremely low porosity, forming the first physical isolation barrier. This significantly reduces the contact surface area between the graphite mold and the blank during sintering, fundamentally inhibiting the high-temperature diffusion and penetration of carbon elements. On the other hand, a composite buffer barrier is constructed by sequentially laying a refractory metal foil isolation layer and a hexagonal boron nitride (h-BN) powder buffer layer inside the graphite mold cavity. The high melting point and low reactivity of the refractory metal foil isolation layer can effectively block the diffusion of carbon atoms from the graphite mold to the blank body. The hexagonal boron nitride powder buffer layer has high-temperature lubrication (promoting uniform stress on the blank body under sintering pressure and avoiding cracks caused by stress concentration), chemical inertness barrier (further isolating carbon elements and absorbing trace oxygen impurities), and thermal shock buffer (relieving thermal stress impact during heating and cooling). The combined effects of these two aspects (through the triple protection of the dense surface layer / h-BN layer / refractory metal foil) construct a gradient carbon barrier system from dense to sparse and from rigid to flexible. This system effectively prevents the graphite mold from carburizing into the workpiece during high-temperature sintering (carbon contamination problem), effectively absorbs and releases the thermal stress generated during cooling due to the difference in thermal expansion coefficients between the mold and the workpiece, preventing cracking of the brittle blank (thermal stress cracking problem), and effectively avoids chemical reactions or mutual diffusion between the barrier layer itself and the workpiece, introducing new impurities (secondary contamination problem). This provides a synergistic technical solution that can systematically and simultaneously solve the three major problems of carbon contamination, thermal stress cracking, and secondary contamination in the hot pressing sintering of refractory metal silicides.

[0008] In this invention, "the billet body" refers to the portion of the refractory metal silicide pre-pressed billet where a dense layer has not yet formed.

[0009] Preferably, in step S1, the refractory metal silicide is selected from tungsten disilicide (WSi2) or molybdenum disilicide (MoSi2).

[0010] Preferably, the purity of the refractory metal silicide is ≥99.999%.

[0011] Unless otherwise specified, all terms "purity" in this invention refer to mass percentage.

[0012] Preferably, the method for preparing the refractory metal silicide blank includes: selecting refractory metal silicide powder with a purity ≥99.999%, pre-forming it by cold isostatic pressing to obtain a blank with a relative density of 50%~60%. The relative density of the blank can be, for example, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0013] In this invention, "relative density" refers to the ratio of the actual density of a material to its theoretical density.

[0014] Preferably, in step S1, the relative density of the surface dense layer is denoted as n1, the relative density of the refractory metal silicide pre-pressed billet is denoted as n2, and n1-n2≥10%.

[0015] Preferably, in step S1, the method used for plastic deformation treatment includes at least one of ultrasonic rolling, ultrasonic compaction, and surface grinding.

[0016] Preferably, the specific conditions for ultrasonic rolling include: an ultrasonic frequency of 20 kHz to 40 kHz, such as 20 kHz, 22 kHz, 25 kHz, 27 kHz, 30 kHz, 33 kHz, 35 kHz, 37 kHz, and 40 kHz, but not limited to the listed values; other unlisted values ​​within the range are also applicable; and a rolling pressure of 5 N / mm. 2 Up to 10 N / mm 2 For example, it could be 5 N / mm 2 6 N / mm 2 7 N / mm 2 8 N / mm 2 9 N / mm 2 10 N / mm 2However, this does not limit the listed values; other unlisted values ​​within the range are also applicable.

[0017] The specific conditions for controlling ultrasonic rolling in this scheme are: ultrasonic frequency of 20 kHz to 40 kHz, and rolling pressure of 5 N / mm. 2 Up to 10 N / mm 2 A dense surface layer with a thickness of 0.1~0.5 mm is formed on the surface through high-frequency impact and plastic deformation.

[0018] Preferably, in step S2, the first refractory metal foil and the second refractory metal foil are each independently selected from tungsten foil or molybdenum foil, and the thickness of the first refractory metal foil and the second refractory metal foil are each independently 0.5~1.5 mm. For example, they can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, but are not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0019] Preferably, the purity of the refractory metal foil is ≥99.95%.

[0020] Preferably, in step S2, the thickness of the first hexagonal boron nitride powder layer and the second hexagonal boron nitride powder layer are each independently 3~8 mm, for example, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, but not limited to the listed values, and other unlisted values ​​within the range are also applicable; the average particle size of the hexagonal boron nitride powder in the first hexagonal boron nitride powder layer and the second hexagonal boron nitride powder layer are each independently 25~50 μm, for example, 25 μm, 28 μm, 30 μm, 33 μm, 35 μm, 37 μm, 40 μm, 42 μm, 45 μm, 47 μm, 50 μm, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0021] Preferably, in step S2, the purity of the hexagonal boron nitride powder in the first hexagonal boron nitride powder layer and the second hexagonal boron nitride powder layer is not less than 99.99%.

[0022] Preferably, the purity of the hexagonal boron nitride powder in the hexagonal boron nitride powder layer is ≥99.99%.

[0023] Preferably, in step S2, the hot pressing sintering adopts a stepped pressurization process, specifically including: applying an initial pressure of 5-10 MPa when the temperature is raised to 600-1000℃, for example, applying 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, and 10 MPa when the temperature is raised to 600℃, 700℃, 800℃, 900℃, and 1000℃, but not limited to the listed values, and other unlisted values ​​within the range are also applicable; then applying a final pressure of 20-40 MPa when the temperature is further raised to 1300-1600℃, for example, applying 20 MPa, 22 MPa, 25 MPa, 27 MPa, 30 MPa, 33 MPa, 35 MPa, 37 MPa, and 40 MPa when the temperature is further raised to 1300℃, 1400℃, 1500℃, and 1600℃, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0024] This scheme adopts a stepped hot-pressing sintering process. Under the protection of an inert atmosphere (preferably Ar or N2), hot-pressing sintering is carried out according to the following stage process parameters: (1) Low-temperature pre-pressing stage (600~1000℃): Apply an initial pressure of 5~10 MPa to promote the initial rearrangement of particles inside the blank, while avoiding cracking of the brittle blank due to rapid pressure increase. (2) High-temperature final sintering stage (1300~1600℃): When the target temperature is reached, apply a final pressure of 20~40 MPa and hold for 30~120 minutes. In this stage, through high-pressure driven plastic flow and liquid phase sintering mechanism (for silicide systems), pore closure and grain boundary migration are achieved, and finally a dense sintered body with a relative density ≥99.5% and uniform grain size (≤20 μm) is obtained.

[0025] In this hot-pressing sintering process, a lower initial pressure is applied during the initial heating stage to ensure a smooth transition of the green body. Once the sintering temperature of 1300~1600℃ is reached, a higher final pressure is applied to promote full densification of the material. During this process, the surface dense layer and the composite buffer barrier produce a subtle synergistic effect: in the pressurization stage, the dense layer ensures uniform pressure transmission; in the cooling stage, the hexagonal boron nitride powder layer effectively releases thermal stress through particle slippage, achieving a perfect unity of rigid pressure transmission and flexible buffering.

[0026] Preferably, in step S2, after hot pressing and sintering, the temperature is controlled to be cooled to below 800°C at a rate of ≤10°C / min, and then the pressure is released in a stepwise manner. First, the pressure is reduced from the final sintering pressure to 50% to 70% of its value at a rate of 0.5 to 2 MPa / min, and the pressure is maintained for 5 to 30 minutes; then the pressure is released to atmospheric pressure at a rate of 1 to 5 MPa / min.

[0027] In step S2 of this scheme, the cooling and pressure relief are controlled: after sintering, the temperature is controlled to be below 800°C at a rate of ≤10°C / min, and then the pressure is relieved in a stepwise manner (rate 1~5 MPa / min) to prevent residual stress from causing microcracks.

[0028] As a preferred option, after hot pressing and sintering, the blank is removed and the surface in contact with the boron nitride layer is machined to remove the contaminant layer. More preferably, the thickness of the contamination layer removed by mechanical processing is 0.2~0.5 mm.

[0029] This method involves removing the hot-pressed and sintered billet from the mold and then performing precision machining on the surface in contact with the h-BN layer to remove a trace amount of contaminant layer with a thickness of 0.2-0.5 mm. After this treatment, the billet surface reaches a metallurgically clean state and can be directly used for the final encapsulation of the coating target.

[0030] In a second aspect, the present invention provides a silicide target material prepared by the method for preparing the silicide target material described in the first aspect above.

[0031] Compared with the prior art, the present invention has the following outstanding advantages and unexpected effects: This invention establishes a systematic technical solution that overcomes the challenges of sintering refractory metal silicides through a series of interconnected processes. The solution first constructs a basic framework by densifying the initial green body, then innovatively densifies the surface layer of the green body, forming a high-density physical barrier. This crucial step provides a solid foundation for preventing contamination in subsequent processes. In the mold assembly stage, a unique composite buffer barrier structure is designed. This barrier, from bottom to top, comprises a refractory metal foil and a hexagonal boron nitride powder layer. The refractory metal foil directly blocks carbon diffusion from the graphite mold, while the hexagonal boron nitride powder layer, with its layered structure and high-temperature stability, effectively blocks carbon and buffers thermal stress through particle slippage. It is particularly noteworthy that hexagonal boron nitride material exhibits superior chemical inertness at high temperatures compared to traditional powders such as zirconium dioxide, completely avoiding secondary reaction contamination with silicides. Finally, through hot-pressing sintering, a high-purity, high-density, and crack-free high-quality silicide target product is successfully obtained. The carbon content of the silicide sputtering target product is stably controlled below 25 ppm, with a purity of ≥99.999% and a relative density of ≥99.5%. The yield has been significantly improved from less than 60% with traditional methods to over 90%, which fully demonstrates the technological advancement and industrial application value of this innovative solution. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0033] Terminology definition: Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of any conflict, the definitions provided herein shall prevail. When trade names appear herein, they are intended to refer to the corresponding product or its active ingredient.

[0034] The terms “comprising,” “including,” “having,” “containing,” or “involving,” and their other variations herein, are inclusive or open-ended and do not exclude other elements or method steps not listed. Those skilled in the art will understand that the foregoing term “comprising” encompasses the meaning of “consisting of.”

[0035] In this invention, the range of values ​​represented by "value A to value B" refers to the range that includes the endpoint values ​​A and B.

[0036] In this invention, "carbon content" refers to the percentage content by mass.

[0037] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0038] Example 1 This embodiment provides a method for preparing a silicide target, comprising the following steps: S1. Pre-treatment of the green body: WSi2 powder with an average particle size of 5 μm (purity > 99.999%) was used and cold isostatic pressing (CIP) was performed at 250 MPa to obtain a pre-pressed green body with a relative density of 72%.

[0039] S2. Perform ultrasonic rolling on the upper and lower surfaces (both sides) of the pre-compressed billet: frequency 30 kHz, pressure 8 N / mm. 2 After processing, a dense surface layer with a thickness of 0.5 mm is formed, and its relative density is increased to 87%, while the relative density of the billet body remains at 72%, resulting in a modified pre-compressed billet.

[0040] S3. Mold Assembly: Lay a 1.0 mm thick, pinhole-free tungsten foil (refractory metal foil) at the bottom of the graphite mold. Evenly lay a 6 mm thick layer of h-BN powder with a purity of 99.99% and an average particle size of 30 μm on the tungsten foil. Place the modified pre-pressed preform with one side of its dense layer facing down on the h-BN powder layer. Symmetrically lay the upper layer of h-BN powder and tungsten foil on top of the modified pre-pressed preform (on the other side of its dense layer).

[0041] S4. Hot pressing sintering: under vacuum degree ≤ 5.0 × 10 -3 Under the condition of Pa, the temperature is increased at a rate of 10℃ / min; a stepped pressurization process is adopted: when the temperature reaches 800℃, an initial pressure of 8 MPa is applied; the temperature is continued to rise to the sintering temperature of 1500℃, while the pressure is increased to a final pressure of 30 MPa, and the temperature and pressure are held for 120 min.

[0042] S5. Post-processing: After sintering, cooling is controlled at a rate of 4℃ / min. When the temperature drops to 750℃, pressure is gradually reduced: first, the pressure is reduced from 30 MPa to 15 MPa (50% of the final pressure) at a rate of 1 MPa / min, and held at this pressure for 15 min; then, the pressure is reduced to atmospheric pressure at a rate of 3 MPa / min. After the pressure is removed and the furnace body cools to room temperature, demolding is performed. Finally, a surface grinder is used to remove 0.3 mm from the upper and lower surfaces of the blank that are in contact with the h-BN buffer layer, yielding the tungsten-silicon alloy target.

[0043] Performance test results: The carbon content of the tungsten-silicon alloy target is 18 ppm, and the purity of the tungsten-silicon alloy target is 99.9995%; the tungsten-silicon alloy target is intact and has no macroscopic or microscopic cracks; the relative density of the tungsten-silicon alloy target is 99.6%.

[0044] Example 2 The difference between the preparation method of the silicide target provided in this embodiment and that in embodiment 1 is that: in step S4, when the temperature reaches 800°C, a pressure of 30 MPa is directly applied, and this pressure of 30 MPa is maintained during the subsequent sintering temperature of 1500°C and the holding period (i.e., no step pressurization process is performed, and the pressure is 30 MPa during the period from 800°C to 1500°C).

[0045] Performance test results: Carbon content of tungsten-silicon alloy target: 24 ppm; Purity of tungsten-silicon alloy target: 99.9993%; Several macroscopic microcracks are visible on the edge of the tungsten-silicon alloy target; Scanning electron microscopy (SEM) shows micro-cracks; Relative density of tungsten-silicon alloy target: 98.7%.

[0046] Example 3 The difference between the preparation method of the silicide target provided in this embodiment and that in Example 1 is that in step S5, when the temperature drops to 750°C, the pressure is removed from 30 MPa to atmospheric pressure at a rate of 3 MPa / min.

[0047] Performance test results: Carbon content of tungsten-silicon alloy target: 22 ppm; Purity of tungsten-silicon alloy target: 99.9993%; Several macroscopic cracks appeared at the edge of the tungsten-silicon alloy target, and obvious microscopic cracks were visible under microscopic observation (SEM); Relative density of tungsten-silicon alloy target: 98.9%.

[0048] Example 4 The difference between the preparation method of the silicide target provided in this embodiment and that in Example 1 is that: in step S3, an h-BN powder layer with an average particle size of 15 μm is used.

[0049] Performance test results: Carbon content of tungsten-silicon alloy target: 65 ppm; Purity of tungsten-silicon alloy target: 99.997%; The tungsten-silicon alloy target is intact overall, and no macroscopic cracks were found, but scanning electron microscopy (SEM) showed local microscopic pores and defects in the near-surface area; Relative density of tungsten-silicon alloy target: 99.0%.

[0050] Comparative Example 1 The difference between the preparation method of the silicide target provided in this comparative example and Example 1 is that the pre-pressed blank with a relative density of 72% obtained in step S1 is directly assembled into a mold in step S3 (i.e., ultrasonic rolling is not performed on the upper and lower surfaces of the pre-pressed blank to form a dense surface layer).

[0051] Performance test results: Due to the lack of a dense surface layer, the surface of the pre-pressed billet was porous. After hot pressing, sintering, and demolding, it was found that h-BN powder was severely embedded in the surface of the billet. In order to completely remove the contamination layer, a 1.0 mm thick contamination layer needed to be ground off. After grinding, the boron content of the tungsten-silicon alloy target was found to be 18 ppm (exceeding the standard), and due to the excessive grinding amount, the material utilization rate was significantly reduced.

[0052] Comparative Example 2 The method for preparing the silicide target provided in this comparative example differs from that in Example 1 in the following steps: Step S3. Mold assembly: A 1.0 mm thick tungsten foil (refractory metal foil) without pinholes is laid at the bottom of a graphite mold. The modified pre-pressed billet is placed on the tungsten foil with its dense surface layer facing down. An upper layer of tungsten foil is symmetrically laid on top of the modified pre-pressed billet (i.e., only tungsten foil is used, without the h-BN powder layer, and the upper and lower surfaces of the modified pre-pressed billet are in direct contact with the tungsten foil).

[0053] Performance test results: During demolding, the blank adhered to the tungsten foil, and multiple macroscopic cracks appeared on the edge of the tungsten-silicon alloy target; the carbon content of the tungsten-silicon alloy target was 320 ppm (seriously exceeding the standard), the purity of the tungsten-silicon alloy target was 99.9%, and the relative density of the tungsten-silicon alloy target was 97.3%.

[0054] Comparative Example 3 The difference between the preparation method of the silicide target provided in this comparative example and that in Example 1 is that a zirconium dioxide (ZrO2) powder layer with an average particle size of 30 μm is used instead of the h-BN powder layer.

[0055] Performance test results: Carbon content of tungsten-silicon alloy target: 22 ppm; Purity of tungsten-silicon alloy target significantly decreased to 99.98%, zirconium content 510 ppm; Discoloration reaction layer is visible on the surface of tungsten-silicon alloy target, and there is a wide network of micro-cracks inside. SEM + energy dispersive spectroscopy (EDS) shows that ZrO2 powder has undergone a significant solid-phase reaction with the silicon (Si) component on the surface of tungsten-silicon alloy target, forming a brittle zirconium silicate compound layer. This reaction layer not only introduces zirconium contamination (secondary contamination), but the huge difference in thermal expansion coefficient between it and the tungsten-silicon alloy target blank induces severe internal stress during cooling, leading to structural damage of tungsten-silicon alloy target; Relative density of tungsten-silicon alloy target: 98.5%.

[0056] Comparative Example 4 The difference between the preparation method of the silicide target provided in this comparative example and that in Example 1 is as follows: Step S3 mold assembly: a 6 mm thick layer of h-BN powder with a purity of 99.99% and an average particle size of 30 μm is uniformly laid at the bottom of the graphite mold; a 1.0 mm thick tungsten foil (refractory metal foil) without pinholes is laid on the h-BN powder layer.

[0057] Performance test results: Carbon content of tungsten-silicon alloy target: 78 ppm; Purity of tungsten-silicon alloy target: 99.994%; Cracks were found in the tungsten-silicon alloy target, with macroscopic cracks present; Scanning electron microscopy (SEM) observation showed that there was a continuous carbon-tungsten diffusion transition layer with a thickness of about 5-10 μm at the interface between the tungsten-silicon alloy target and the tungsten foil, and the porosity of the near-interface region inside the tungsten-silicon alloy target was increased; Relative density of tungsten-silicon alloy target: 98.8%.

[0058] The carbon content, purity, billet condition, and relative density of the tungsten-silicon alloy targets prepared in the above embodiments and comparative examples are shown in Table 1 below.

[0059] Table 1

[0060] The method for preparing silicide targets provided by this invention constructs a gradient carbon inhibition system to ensure that the depth of interfacial carbon contamination is ≤50 μm during high-temperature sintering of the green body, thereby achieving: anti-carburization (carbon content ≤25 ppm), high purity (≥99.999%) and high density (relative density ≥98.7%).

[0061] 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 silicide target, characterized in that, Includes the following steps: S1. The two sides of the refractory metal silicide pre-compressed billet are plastically deformed to form a dense surface layer, thus obtaining a modified pre-compressed billet; S2. A first refractory metal foil is laid in the mold cavity, and a first hexagonal boron nitride powder layer is laid on the first refractory metal foil. The surface dense layer of the modified pre-pressed blank is placed on the first hexagonal boron nitride powder layer, and a second hexagonal boron nitride powder layer and a second refractory metal foil are sequentially laid on the surface dense layer on the other side of the modified pre-pressed blank. The blank is then hot-pressed and sintered to obtain a silicide target.

2. The method for preparing the silicide target according to claim 1, characterized in that, In step S1, the refractory metal silicide is selected from tungsten disilicide or molybdenum disilicide.

3. The method for preparing the silicide target according to claim 1 or 2, characterized in that, In step S1, the relative density of the surface dense layer is denoted as n1, and the relative density of the refractory metal silicide pre-pressed billet is denoted as n2, where n1-n2≥10%.

4. The method for preparing the silicide target according to claim 3, characterized in that, In step S1, the plastic deformation treatment method includes at least one of ultrasonic rolling, ultrasonic vibration, and surface grinding.

5. The method for preparing the silicide target according to claim 4, characterized in that, The specific conditions for ultrasonic rolling include: ultrasonic frequency of 20 kHz to 40 kHz and rolling pressure of 5 N / mm. 2 Up to 10 N / mm 2 .

6. The method for preparing the silicide target according to claim 1, 4, or 5, characterized in that, In step S2, the first refractory metal foil and the second refractory metal foil are each independently selected from tungsten foil or molybdenum foil, and the thickness of the first refractory metal foil and the second refractory metal foil is each independently 0.5~1.5 mm.

7. The method for preparing the silicide target according to claim 6, characterized in that, In step S2, the thickness of the first hexagonal boron nitride powder layer and the second hexagonal boron nitride powder layer are each independently 3~8 mm, and the average particle size of the hexagonal boron nitride powder in the first hexagonal boron nitride powder layer and the second hexagonal boron nitride powder layer is each independently 25~50 μm.

8. The method for preparing the silicide target according to claim 1 or 7, characterized in that, In step S2, the hot pressing sintering adopts a stepped pressurization process, specifically including: applying an initial pressure of 5-10 MPa when the temperature is raised to 600-1000℃, and then applying a final pressure of 20-40 MPa when the temperature is further raised to 1300-1600℃.

9. The method for preparing the silicide target according to claim 1, characterized in that, In step S2, after hot pressing and sintering is completed, the temperature is controlled to be cooled to below 800°C at a rate of ≤10°C / min. Then, the pressure is released in a stepwise manner. First, the pressure is reduced from the final sintering pressure to 50% to 70% of its value at a rate of 0.5 to 2 MPa / min and held for 5 to 30 minutes. Then, the pressure is released to atmospheric pressure at a rate of 1 to 5 MPa / min.

10. A silicide target, characterized in that, It is prepared by the method for preparing silicide targets as described in any one of claims 1 to 9.

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