High-purity ruthenium target material for sputtering and preparation method thereof

Abstract

The invention discloses a high-purity ruthenium target material for sputtering and a preparation method thereof, and belongs to the technical field of target material preparation. The density of the high-purity ruthenium target for sputtering is larger than or equal to 99.5%, the oxygen content is smaller than 200 ppm, and the average grain size of ruthenium is smaller than 10 micrometers. The preparation method comprises the steps that ruthenium powder is put into a die to be pre-pressed after being put into a vacuum hot-pressing sintering furnace, then under the vacuum condition, gradient heating is conducted to the sintering temperature of 1000-1200 DEG C, then heat preservation is conducted, gradient pressurization is conducted to the hot-pressing pressure of 35-40 MPa, hot-pressing sintering is conducted for 90-150 min, then furnace cooling is conducted, a ruthenium pre-target blank is obtained, the ruthenium pre-target blank is put into a hot isostatic pressing sintering furnace after being subjected to sheathing degassing, and the ruthenium target blank is obtained. And sintering for 3-5 hours at the temperature of 1300-1450 DEG C under the pressure of 110-160 MPa under the vacuum condition, cooling along with the furnace, recovering the pressure, and machining to obtain the finished ruthenium target with high density, high purity, low oxygen content and uniform and fine grain structure.

Description

Technical Field

[0001] The invention belongs to the technical field of target material preparation, and in particular relates to a high-purity ruthenium target material for sputtering and a preparation method thereof. Background Art

[0002] High-purity ruthenium metal targets have high purity, high melting point, high conductivity and chemical stability. High purity provides a guarantee for the production of high-quality films, and high melting point and high boiling point make its coating performance good. Ruthenium targets are mainly used to prepare various films with excellent properties such as high hardness, wear resistance, corrosion resistance, high temperature resistance and oxidation resistance, and are widely used in optics, electronics, semiconductors, aerospace, chemical industry and other fields. Especially in magnetic recording multilayer film structures, ruthenium has the effects of reducing the lattice mismatch between the upper and lower layers, reducing interface stress, reducing noise and increasing thermal stability. Ruthenium films can be prepared by magnetron sputtering, so high-purity ruthenium targets have become key materials. At present, my country's high-purity ruthenium targets mainly rely on imports. The independently produced ruthenium targets have low purity, insufficient density, and large grain size.

[0003] Patent document CN115233175A provides a method for preparing a ruthenium rotary sputtering target, which solves the volume shrinkage problem during the target molding process by artificial pressure molding, vacuum hot pressing molding, and hot isostatic pressing molding, making the shape of the target more controllable. However, the vacuum hot pressing heating method of this method adopts a uniform heating method, the density of the target is insufficient, and the microscopic morphology will be uneven.

[0004] Therefore, there is an urgent need for a high-purity ruthenium target for sputtering and a preparation method thereof to solve the above problems. Summary of the invention

[0005] One of the purposes of the present invention is to provide a high-purity ruthenium target for sputtering to solve the problem of low purity and insufficient density of the existing ruthenium target;

[0006] A second object of the present invention is to provide a method for preparing a high-purity ruthenium target for sputtering, so as to solve the problem of uneven microscopic morphology of the ruthenium target in the target preparation process.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] In a first aspect, a high-purity ruthenium target for sputtering has a density of ≥99.5%, an oxygen content of <200 ppm, an average ruthenium grain size of <10 μm, and a flatness error of ≤0.4 mm.

[0009] In a second aspect, a method for preparing a high-purity ruthenium target for sputtering comprises the following steps:

[0010] Step 1: Mold

[0011] Put the raw ruthenium powder into the graphite mold and flatten it;

[0012] Step 2: Hot Pressing and Sintering

[0013] The graphite mold filled with ruthenium powder is placed in a vacuum hot pressing sintering furnace for pre-pressing; then, under vacuum conditions, the temperature is gradually increased to a sintering temperature of 1000-1200°C and then kept warm, and then the hot pressing pressure is gradually increased to 35-40MPa, and the temperature is lowered along with the furnace after hot pressing sintering for 90-150 minutes to obtain a ruthenium pre-target blank with a density of 85%-90%;

[0014] Step 3: Wrap

[0015] Encase the ruthenium pre-target blank according to the encasement assembly, and perform degassing treatment after encasement to obtain a degassed encasement;

[0016] Step 4: Hot Isostatic Pressing

[0017] The degassed package is placed in a hot isostatic pressing furnace, and sintered for 3-5 hours at a temperature of 1300-1450°C, a pressure of 110-160MPa, and a vacuum condition, and then the pressure is recovered by cooling the furnace to obtain a ruthenium target blank with a density of ≥99.5%;

[0018] Step 5: Machining

[0019] The ruthenium target blank is grinded according to the drawing requirements, and then the outer circle is processed to obtain a target blank with qualified size. Relevant defect and density tests are carried out, and vacuum packaging is carried out if no abnormalities are found.

[0020] Furthermore, in step 1, the purity of the raw ruthenium powder is ≥99.95%, and the median particle size is 6-10 μm.

[0021] Furthermore, in step 1, the graphite mold is a high-purity graphite mold, graphite paper of corresponding size is cut and placed on the bottom and inner side of the mold, ruthenium powder is spread flat in the graphite mold, and the powder is spread flat with a powder spreading shovel or other tools.

[0022] Furthermore, in step 2, the pre-compression pressure is 6-10 MPa, the pre-compression pressure increasing rate is 0.1-0.3 MPa / min, and the pressure is maintained for 10-15 minutes after reaching the pre-compression pressure.

[0023] Furthermore, in step 2, the vacuum degree is ≤5Pa.

[0024] Furthermore, in step 2, the gradient heating is specifically as follows: first, the temperature is uniformly increased to 400-600°C at a rate of 8-10°C / min, then the temperature is uniformly increased to 800-1000°C at a rate of 5-8°C / min, and kept at this temperature for 45-60min; then the temperature is uniformly increased to the sintering temperature at a rate of 3-5°C / min, and kept at this temperature for 45-60min.

[0025] Furthermore, in step 2, the gradient pressurization is specifically as follows: first, the first stage of uniform pressurization is started at a rate of 0.25-0.35 MPa / min to 20-25 MPa, and then the second stage of uniform pressurization is started at a rate of 0.1-0.2 MPa / min to the hot pressing pressure.

[0026] Furthermore, in step 2, after the hot pressing sintering is completed, the temperature is lowered to 100-200° C. in the furnace.

[0027] 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 the bottom, and then low carbon steel partitions and graphite fiber paper are laid on the bottom in sequence, the ruthenium pre-target blank is placed in the package, and graphite fiber paper, low carbon steel partitions and graphite fiber paper are placed on the ruthenium pre-target blank in sequence, and finally the package cover plate with a degassing port is welded to the top of the package, and the degassing pipe is welded to the degassing port.

[0028] Low carbon steel or stainless steel is used as the outer sheath material, which has low cost and good machinability; graphite paper is placed between the cover plate and the pre-target blank to prevent impurities from entering the target material; and the degassing pipe is welded to the degassing port and the sealing performance is good after the air is closed.

[0029] Furthermore, in step 3, the degassing process first uses a helium mass spectrometer leak detector to detect leaks on the package, and then degassing is performed by heating; the degassing temperature is 400-550°C, the degassing time is 3-6h, and the vacuum degree inside the package is less than 2×10 -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.

[0030] Furthermore, 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.

[0031] Furthermore, in step 5, the feed amount of the grinding machine is 2-10 μm, and the wire cutting rate of the electric spark wire cutting is 2-5 mm / min.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The present invention provides a high-purity ruthenium target for sputtering, which has the characteristics of high density, high purity, low oxygen content, flat target blank, small flatness error, uniform and fine grain structure, excellent sputtering performance, etc. Since ruthenium is a precious metal, the preparation cost of high-purity ruthenium is extremely high. The present invention adopts a combination of hot pressing sintering + hot isostatic pressing sintering to prepare a high-purity ruthenium target, and controls the internal microstructure of the target blank by combining gradient heating + gradient pressurization during the hot pressing sintering process, thereby improving the density of the target blank and the uniformity of its microscopic morphology.

[0034] 2. In the present invention, before hot pressing and sintering, the ruthenium powder needs to be molded to ensure that the powder is spread evenly, and pre-pressing is performed before heating. Evacuate to below 5Pa and start heating. The present invention adopts a staged heating method: a fast heating rate is used at low temperatures, a slow heating rate is used at high temperatures, and a heat preservation step is set, the purpose of which is to obtain a real and effective temperature environment and a fully uniform temperature field; heat preservation at 800-1000℃ for 45-60min and 1000-1200℃ for 45-60min can reduce the longitudinal and radial temperature gradients of the powder, make the temperature field inside the powder layer uniform, and then make the internal microstructure of the target blank uniform. If the temperature is directly raised to the highest temperature without setting a heat preservation step, the temperature field will be distorted, the density of the pre-target blank will be insufficient, and the microscopic morphology will be uneven.

[0035] The hot pressing also uses a segmented pressurization method: a high-rate pressure increase is used at the beginning of the pressurization, and a low pressure increase rate is used after the pressure reaches a certain value, that is, after the 1000-1200℃ insulation is completed, the pressure is first increased by 20-25MPa at a rate of 0.25-0.35MPa / min; then the pressure is increased by 35-40MPa at a rate of 0.1-0.2MPa / min. On the one hand, this pressure increase method matches the hot pressing equipment, and on the other hand, it allows the sintering neck to fully grow and combine in the early stage of sintering, and the densification rate is fast. In the later stage of sintering, the densification is mainly carried out by creep, which requires a slow pressure increase rate. This pressure increase method improves the density of the target material while also obtaining a uniform and fine grain structure. The density of the high-purity ruthenium pre-target blank obtained by hot pressing sintering can reach 85%-90%.

[0036] Finally, the hot isostatic pressing sintering temperature is 1300°C-1450°C, the pressure is 110-160MPa, and the holding time is 3-5h, and a high-purity ruthenium target with fine grain size, oxygen content <200ppm, and density ≥99.5% can be obtained.

[0037] 3. The preparation method provided by the present invention can be widely used in the preparation process of sputtering targets of different sizes by adjusting the size, especially the preparation of large-sized (diameter > 440 mm) high-purity ruthenium targets, and has broad application prospects in the field of powder metallurgy preparation of large-sized targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention will be further described below in conjunction with the accompanying drawings.

[0039] Figure 1 It is a schematic diagram of a process flow of preparing a high-purity ruthenium target for sputtering according to the present invention;

[0040] Figure 2 It is a schematic diagram of the packaging assembly structure in the packaging process of step 3 of the present invention;

[0041] Figure 3 This is a physical picture of a large-sized high-purity ruthenium target for sputtering prepared in Example 1 of the present invention;

[0042] Figure 4 is a graph showing the relationship between the temperature rise process and the pressure rise process and time in the hot pressing sintering process of step 2 of embodiment 2 of the present invention;

[0043] Figure 5 It is a relationship diagram between the temperature rise process and the pressure rise process and time in the hot pressing sintering process of step 2 of comparative example 1 of the present invention;

[0044] Figure 6 It is a relationship diagram between the temperature rise process and the pressure rise process and time in the hot pressing sintering process of step 2 of comparative example 2 of the present invention;

[0045] Figure 7 It is a relationship diagram between the temperature rise process and the pressure rise process and time in the hot pressing sintering process of step 2 of comparative example 3 of the present invention;

[0046] Figure 8 This is a low-magnification cross-sectional microscopic morphology SEM image of the high-purity ruthenium target for sputtering prepared in Example 1 of the present invention;

[0047] Fig. 9 This is a high-magnification cross-sectional microscopic morphology SEM image of the high-purity ruthenium target for sputtering prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0048] 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0049] A high-purity ruthenium target material for sputtering, wherein the target material has a density of ≥99.5%, an oxygen content of <200ppm, an average ruthenium grain size of <10μm, and a flatness error of ≤0.4mm.

[0050] See also Figure 1 , a method for preparing a high-purity ruthenium target for sputtering, comprising the following steps:

[0051] Step 1: Mold

[0052] First, cut graphite paper of corresponding size and place it on the bottom and inner side of a high-purity graphite mold of appropriate size. Place raw ruthenium powder with a purity of ≥99.95% and a median particle size of 6-10μm in the graphite mold and flatten the powder with a powder shovel or other tools.

[0053] Step 2: Hot Pressing and Sintering

[0054] Put the graphite mold filled with ruthenium powder into a vacuum hot pressing sintering furnace, increase the pressure at a rate of 0.1-0.3MPa / min, and after reaching the pre-pressing pressure of 6-10MPa, maintain the pressure for 10-15 minutes and then release the pressure;

[0055] Then evacuate to a vacuum degree of ≤5Pa, and use a gradient heating method to uniformly heat to 400-600°C at a rate of 8-10°C / min, then uniformly heat to 800-1000°C at a rate of 5-8°C / min, and keep warm for 45-60min, then uniformly heat at a rate of 3-5°C / min, and after reaching the sintering temperature of 1000-1200°C, keep warm for 45-60min;

[0056] Then, a gradient pressurization method is adopted, and the first stage of uniform pressurization is started at a rate of 0.25-0.35MPa / min to 20-25MPa, and then the second stage of uniform pressurization is started at a rate of 0.1-0.2MPa / min. After reaching the hot pressing pressure setting value of 35-40MPa, the heat-maintaining pressure is maintained and hot-pressed for 90-150min; after the hot pressing sintering is completed, the temperature is lowered to 100-200°C with the furnace to obtain a ruthenium pre-target blank;

[0057] Step 3: Wrap

[0058] Design the package according to the finished product size. The package assembly diagram is as follows: Figure 2 As shown, Figure 2 In the process, the sheath material is low carbon steel or stainless steel, the inner wall of the sheath is padded with graphite fiber paper and a partition, the ruthenium pre-target blank is placed in the sheath, the graphite fiber paper and the partition are placed on the ruthenium pre-target blank in sequence, and then the sheath cover plate with a degassing port is welded to the top of the sheath, and the degassing pipe is welded to the degassing port;

[0059] After the package is wrapped, it is degassed and leak-checked with a helium mass spectrometer. After the leak is checked, it is heated for degassing at a temperature of 400-550°C and a degassing time of 3-6 hours. When the vacuum degree inside the package is less than 2×10 -3 After Pa, the degassing pipe near the package is clamped flat and the excess part is cut off to form a closed vacuum environment in the package;

[0060] Step 4: Hot Isostatic Pressing

[0061] The degassed package is placed in a hot isostatic pressing sintering furnace, and sintered for 3-5 hours at a temperature of 1300-1450°C, a pressure of 110-160MPa, and vacuum conditions; after sintering, the temperature is lowered and the pressure is recovered along with the furnace until the temperature is less than 100°C and the pressure of the hot isostatic pressing sintering furnace is 0MPa, and the ruthenium target blank is obtained when the furnace discharge standard is met;

[0062] Step 5: Machining

[0063] The outer sheath of the ruthenium target blank is removed and the target blank is grinded according to the requirements of the drawing. The feed amount of the grinder is 2-10μm and the wire cutting rate 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 there are no abnormalities, it is vacuum packed to obtain the finished ruthenium target material.

[0064] Example 1

[0065] This embodiment provides a method for preparing a high-purity ruthenium target for sputtering, comprising the following steps:

[0066] Step 1: Mold

[0067] Place the raw ruthenium powder with a purity of ≥99.95% and a median particle size of 8 μm in a graphite mold and lay it flat;

[0068] Step 2: Hot Pressing and Sintering

[0069] Put the graphite mold filled with ruthenium powder into a vacuum hot pressing sintering furnace, increase the pressure at a rate of 0.2MPa / min, and after reaching the pre-pressing pressure of 10MPa, maintain the pressure for 13 minutes and then release the pressure to 0MPa; evacuate to a vacuum degree of 0Pa;

[0070] First, the temperature was raised to 600°C at a rate of 10°C / min, then raised to 900°C at a rate of 5°C / min, and kept at that temperature for 60 minutes. Then, the temperature was raised at a rate of 3°C / min, and after reaching the sintering temperature of 1150°C, it was kept at that temperature for 60 minutes.

[0071] Then, a gradient pressurization method is adopted, and the first stage of uniform pressurization is started at a rate of 0.35 MPa / min to 25 MPa, and then the second stage of uniform pressurization is started at a rate of 0.2 MPa / min. After reaching the hot pressing pressure setting value of 40 MPa, the hot pressing sintering is carried out for 120 minutes with heat preservation and pressure maintenance; after the hot pressing sintering is completed, the temperature is lowered to 200° C. with the furnace to obtain a ruthenium pre-target blank;

[0072] Step 3: Wrap

[0073] For the ruthenium pre-target blank, Figure 2 The structure is assembled and packaged, and then degassed. A helium mass spectrometer is used to detect leaks in the package. After the leak detection is OK, the temperature is increased for degassing. The degassing temperature is 450℃ and the degassing time is 5h. When the vacuum degree inside the package is less than 2×10 -3 Degassing ends after Pa;

[0074] Step 4: Hot Isostatic Pressing

[0075] The degassed package is placed in a hot isostatic pressing sintering furnace, and sintered for 5 hours at a temperature of 1450°C, a pressure of 150MPa, and a vacuum condition; after sintering, the temperature is lowered and the pressure is recovered along with the furnace, and a ruthenium target blank is obtained when the standard for exiting the furnace is met;

[0076] Step 5: Machining

[0077] The outer sheath of the ruthenium target blank is removed and the target blank is grinded according to the requirements of the drawing. The feed amount of the grinder is 8μm and the wire cutting rate of the electric spark wire cutting is 3mm / min. The outer circle is then processed to obtain a target blank with qualified size. Relevant defect and density tests are carried out. Vacuum packaging is performed if no abnormalities are found.

[0078] The actual picture of the large-sized ruthenium target prepared in this example is as follows Figure 3 shown.

[0079] Example 2

[0080] This embodiment provides a method for preparing a high-purity ruthenium target for sputtering, comprising the following steps:

[0081] Step 1: Mold

[0082] Place the raw ruthenium powder with a purity of ≥99.95% and a median particle size of 8 μm in a graphite mold and lay it flat;

[0083] Step 2: Hot Pressing and Sintering

[0084] Place the graphite mold filled with ruthenium powder into a vacuum hot-pressing sintering furnace, increase the pressure at a rate of 0.2MPa / min, and after reaching the pre-pressing pressure of 10MPa, maintain the pressure for 13 minutes and then release the pressure to 0MPa; evacuate to a vacuum degree of 0Pa; refer to Figure 4 ,

[0085] First, the temperature was raised to 600°C at a rate of 10°C / min, then raised to 800°C at a rate of 5°C / min, and kept at that temperature for 60 minutes. Then, the temperature was raised at a rate of 3°C / min, and after reaching the sintering temperature of 1100°C, it was kept at that temperature for 60 minutes.

[0086] Then, a gradient pressurization method is adopted, and the first stage of uniform pressurization is started at a rate of 0.3 MPa / min to 20 MPa, and then the second stage of uniform pressurization is started at a rate of 0.2 MPa / min. After reaching the hot pressing pressure setting value of 40 MPa, the hot pressing sintering is carried out for 120 minutes with heat preservation and pressure maintenance; after the hot pressing sintering is completed, the temperature is lowered to 200° C. with the furnace to obtain a ruthenium pre-target blank;

[0087] Step 3: Wrap

[0088] For the ruthenium pre-target blank, Figure 2The structure is assembled and packaged, and then degassed. A helium mass spectrometer is used to detect leaks in the package. After the leak detection is OK, the temperature is increased for degassing. The degassing temperature is 450℃ and the degassing time is 5h. When the vacuum degree inside the package is less than 2×10 -3 Degassing ends after Pa;

[0089] Step 4: Hot Isostatic Pressing

[0090] The degassed package is placed in a hot isostatic pressing sintering furnace, and sintered for 5 hours at a temperature of 1350°C, a pressure of 150MPa, and a vacuum condition; after sintering, the temperature is lowered and the pressure is recovered along with the furnace, and a ruthenium target blank is obtained when the standard for exiting the furnace is met;

[0091] Step 5: Machining

[0092] The outer sheath of the ruthenium target blank is removed and the target blank is grinded according to the requirements of the drawing. The feed amount of the grinder is 8μm and the wire cutting rate of the electric spark wire cutting is 3mm / min. The outer circle is then processed to obtain a target blank with qualified size. Relevant defect and density tests are carried out. Vacuum packaging is performed if no abnormalities are found.

[0093] Example 3

[0094] This embodiment provides a method for preparing a high-purity ruthenium target for sputtering, comprising the following steps:

[0095] Step 1: Mold

[0096] Place the raw ruthenium powder with a purity of ≥99.95% and a median particle size of 8 μm in a graphite mold and lay it flat;

[0097] Step 2: Hot Pressing and Sintering

[0098] The graphite mold filled with ruthenium powder was placed in a vacuum hot-pressing sintering furnace, and the pressure was increased at a rate of 0.2 MPa / min. After reaching the pre-pressing pressure of 10 MPa, the pressure was maintained for 13 minutes and then the pressure was released to 0 MPa.

[0099] Then evacuate to a vacuum degree of ≤5Pa, and use a gradient heating method to uniformly heat to 500°C at a rate of 9°C / min, then uniformly heat to 1000°C at a rate of 7°C / min, and keep warm for 50 minutes, then uniformly heat at a rate of 5°C / min, and after reaching the sintering temperature of 1200°C, keep warm for 50 minutes;

[0100] Then, a gradient pressurization method is adopted, and the first stage of uniform pressurization is started at a rate of 0.3MPa / min to 20MPa, and then the second stage of uniform pressurization is started at a rate of 0.15MPa / min. After reaching the hot pressing pressure setting value of 40MPa, the hot pressing sintering is carried out for 120min at a temperature of 40MPa. After the hot pressing sintering is completed, the temperature is lowered to 200°C with the furnace to obtain a ruthenium pre-target blank;

[0101] Step 3: Wrap

[0102] For the ruthenium pre-target blank, Figure 2 The structure is assembled and packaged, and then degassed. A helium mass spectrometer is used to detect leaks in the package. After the leak detection is OK, the temperature is increased for degassing. The degassing temperature is 450℃ and the degassing time is 5h. When the vacuum degree inside the package is less than 2×10 -3 Degassing ends after Pa;

[0103] Step 4: Hot Isostatic Pressing

[0104] The degassed package is placed in a hot isostatic pressing sintering furnace, and sintered for 4 hours at a temperature of 1400°C, a pressure of 120MPa, and a vacuum condition; after sintering, the temperature is lowered and the pressure is recovered along with the furnace, and a ruthenium target blank is obtained when the standard for exiting the furnace is met;

[0105] Step 5: Machining

[0106] The outer sheath of the ruthenium target blank is removed and the target blank is grinded according to the requirements of the drawing. The feed amount of the grinder is 8μm and the wire cutting rate of the electric spark wire cutting is 3mm / min. The outer circle is then processed to obtain a target blank with qualified size. Relevant defect and density tests are carried out. Vacuum packaging is performed if no abnormalities are found.

[0107] Comparative Example 1

[0108] This comparative example provides a method for preparing a ruthenium target material, which is different from Example 2 in that step 2: hot pressing sintering adopts the following process:

[0109] Place the graphite mold filled with ruthenium powder into a vacuum hot-pressing sintering furnace, increase the pressure at a rate of 0.2MPa / min, and after reaching the pre-pressing pressure of 10MPa, maintain the pressure for 13 minutes and then release the pressure to 0MPa; evacuate to a vacuum degree of ≤5Pa; refer to Figure 5 ,

[0110] First, the temperature was raised uniformly at a rate of 4.2°C / min to 1100°C and kept at that temperature for 60 minutes.

[0111] Then, a gradient pressurization method is adopted, and the first stage of uniform pressurization is started at a rate of 0.3 MPa / min to 20 MPa, and then the second stage of uniform pressurization is started at a rate of 0.2 MPa / min. After reaching the hot pressing pressure setting value of 40 MPa, the hot pressing sintering is carried out for 120 minutes with heat preservation and pressure maintenance; after the hot pressing sintering is completed, the temperature is lowered to 200° C. with the furnace to obtain a ruthenium pre-target blank;

[0112] The remaining steps and parameters remain the same.

[0113] Comparative Example 2

[0114] This comparative example provides a method for preparing a ruthenium target material, which is different from Example 2 in that step 2: hot pressing sintering adopts the following process:

[0115] Place the graphite mold filled with ruthenium powder into a vacuum hot-pressing sintering furnace, increase the pressure at a rate of 0.2MPa / min, and after reaching the pre-pressing pressure of 10MPa, maintain the pressure for 13 minutes and then release the pressure to 0MPa; evacuate to a vacuum degree of ≤5Pa; refer to Figure 6 ,

[0116] First, the temperature was raised to 600°C at a rate of 10°C / min, then raised to 800°C at a rate of 5°C / min, and kept at that temperature for 60 minutes. Then, the temperature was raised at a rate of 3°C / min, and after reaching the sintering temperature of 1100°C, it was kept at that temperature for 60 minutes.

[0117] Then, the pressure is increased uniformly at a rate of 0.24 MPa / min to 40 MPa, and the hot pressing sintering is performed for 120 minutes under the same temperature and pressure. After the hot pressing sintering is completed, the temperature is lowered to 200° C. with the furnace to obtain a ruthenium pre-target blank.

[0118] The remaining steps and parameters remain the same.

[0119] Comparative Example 3

[0120] This comparative example provides a method for preparing a ruthenium target material, which is different from Example 2 in that step 2: hot pressing sintering adopts the following process:

[0121] Place the graphite mold filled with ruthenium powder into a vacuum hot-pressing sintering furnace, increase the pressure at a rate of 0.2MPa / min, and after reaching the pre-pressing pressure of 10MPa, maintain the pressure for 13 minutes and then release the pressure to 0MPa; evacuate to a vacuum degree of ≤5Pa; refer to Figure 7 ,

[0122] The method of gradient heating and gradient pressurization is adopted at the same time, the temperature is uniformly increased to 600°C at a rate of 10°C / min, and then the temperature is uniformly increased to 800°C at a rate of 5°C / min, and the temperature is kept for 60 minutes, and then the temperature is uniformly increased at a rate of 3°C / min. After reaching the sintering temperature of 1100°C, the temperature is kept for 60 minutes; at the same time, the first stage of uniform pressurization is started at a rate of 0.3MPa / min to 20MPa, and then the second stage of uniform pressurization is started at a rate of 0.2MPa / min. After reaching the hot pressing pressure setting value of 40MPa, the temperature is kept and the pressure is kept hot pressed for 120 minutes; after the hot pressing sintering is completed, the temperature is lowered to 200°C with the furnace to obtain the ruthenium pre-target blank;

[0123] The remaining steps and parameters remain the same.

[0124] Comparative Example 4

[0125] This comparative example provides a method for preparing a ruthenium target material, which is different from Example 2 in that step 2: hot pressing sintering adopts the following process:

[0126] Put the graphite mold filled with ruthenium powder into a vacuum hot pressing sintering furnace, increase the pressure at a rate of 0.2MPa / min, and after reaching the pre-pressing pressure of 10MPa, maintain the pressure for 13 minutes and then release the pressure to 0MPa; evacuate to a vacuum degree of 0Pa;

[0127] The sintering was carried out at a constant temperature and pressure of 1100°C and a pressure of 40 MPa for 600 min. After the hot pressing sintering, the temperature was lowered to 200°C with the furnace to obtain a ruthenium pre-target blank.

[0128] The remaining steps and parameters remain the same.

[0129] The surface flatness of the ruthenium target blanks before machining in the preparation processes of Examples 1-3 and Comparative Examples 1-4 was tested, the surface flatness was detected with a plane detection ruler, and the flatness error value was recorded; if the surface flatness of the target blank before machining is higher and the flatness error value is smaller, the machining allowance for subsequent machining will be smaller.

[0130] Density test was performed on ruthenium pre-target and ruthenium target; the average grain size, purity and oxygen content of the finished ruthenium target were tested. The density was tested by the traditional Archimedean method, and the density was calculated by (test density ÷ theoretical density) × 100%; the microstructure was observed by scanning electron microscopy (SEM), and then the average grain size was calculated by the intercept method; the purity was tested by GDMS; and the oxygen content was tested by LECO-oxygen, nitrogen and hydrogen analyzer.

[0131] The test results are shown in Table 1:

[0132] Table 1

[0133]

[0134] The SEM image of the cross-section microstructure of the high-purity ruthenium target prepared in Example 1 is as follows: Figure 8 As shown; the high-magnification cross-sectional micromorphology SEM image is as follows Fig. 9 As shown; it can be seen from the test results that by regulating the temperature rise process during hot pressing and sintering, the longitudinal and radial temperature gradients of the ruthenium powder can be effectively reduced, the uniformity of the temperature in the powder layer can be improved, and the microscopic morphology inside the target material (cross section) can be made uniform and dense; on this basis, the pressure increase method is further adjusted so that the inside of the ruthenium powder can adapt to the change in the densification rate, and the prepared target material has a uniform and fine grain structure.

[0135] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0136] Although 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 the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-purity ruthenium target for sputtering, characterized in that: The density of the ruthenium target material is ≥99.5%, the oxygen content is <200ppm, the average grain size of ruthenium is <10μm, and the flatness error is ≤0.4mm.

2. A method for preparing a high-purity ruthenium target for sputtering as claimed in claim 1, characterized in that: The following steps are involved: Step 1: Mold Put the raw ruthenium powder into the graphite mold and flatten it; Step 2: Hot Pressing and Sintering The graphite mold filled with ruthenium powder is placed in a vacuum hot pressing sintering furnace for pre-pressing; then, under vacuum conditions, the temperature is gradually increased to a sintering temperature of 1000-1200°C and then kept warm, and then the hot pressing pressure is gradually increased to 35-40MPa, and the hot pressing sintering is performed for 90-150 minutes and then the temperature is lowered along with the furnace to obtain a ruthenium pre-target blank; Step 3: Wrap Encapsulating the ruthenium pre-target blank, and performing a degassing treatment after encapsulation to obtain a degassed encapsulation; Step 4: Hot Isostatic Pressing The degassed package is placed in a hot isostatic pressing furnace, and sintered for 3-5 hours at a temperature of 1300-1450°C, a pressure of 110-160MPa, and a vacuum condition, and then the temperature is lowered and the pressure is recovered to obtain a ruthenium target blank; Step 5: Machining The ruthenium target blank is processed by a grinder to obtain a target material with qualified size. The target material is then tested for relevant defects and density. If no abnormality is found, it is vacuum packaged.

3. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, characterized in that: In step 1, the purity of the raw ruthenium powder is ≥99.95%, and the median particle size is 6-10 μm.

4. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, characterized in that: In step 2, the pre-compression pressure is 6-10MPa, the pre-compression pressure increase rate is 0.1-0.3MPa / min, and the pressure is maintained for 10-15 minutes after reaching the pre-compression pressure.

5. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, characterized in that: In step 2, the gradient heating is specifically as follows: first, the temperature is uniformly increased to 400-600°C at a rate of 8-10°C / min, then the temperature is uniformly increased to 800-1000°C at a rate of 5-8°C / min, and kept at this temperature for 45-60min; then, the temperature is uniformly increased to the sintering temperature at a rate of 3-5°C / min, and kept at this temperature for 45-60min.

6. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, characterized in that: In step 2, the gradient pressurization is specifically as follows: first, the first stage of uniform pressurization is started at a rate of 0.25-0.35 MPa / min to 20-25 MPa, and then the second stage of uniform pressurization is started at a rate of 0.1-0.2 MPa / min to the hot pressing pressure.

7. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, characterized in that: In step 2, after the hot pressing sintering is completed, the temperature is lowered to 100-200°C in the furnace.

8. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, characterized in that: In step 3, the degassing temperature is 400-550°C, the degassing time is 3-6h, and the degassing is performed until the vacuum degree inside the package is less than 2×10 -3 Pa.

9. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, 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.

10. The method for preparing a high-purity ruthenium target for sputtering according to claim 2, 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.

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