A ruthenium target and a method for manufacturing the same

Abstract

The present application relates to the technical field of target material manufacturing, and in particular to a ruthenium target material and a preparation method thereof. The method comprises: high-pressure cold die forming of ruthenium powder to obtain a ruthenium blank; placing the ruthenium blank in a metal sheath made of stainless steel or low-carbon steel, high-temperature vacuum pumping and exhaust, and welding to obtain a metal sheath containing the ruthenium blank; two-stage hot isostatic pressing sintering of the metal sheath containing the ruthenium blank; the pressure of the first-stage sintering is 130-150 MPa, and the temperature is greater than or equal to 1000 DEG C; the pressure of the second-stage sintering is 160-180 MPa, and the temperature of the second-stage sintering is higher than the temperature of the first-stage sintering by more than 150 DEG C. The ruthenium target material prepared by the present application has an average grain size of less than 5 mu m, a relative density of more than 99.5%, and the ruthenium target material and the metal sheath skin are easy to separate and not to adhere, and the target material yield is more than 98%, thereby reducing the manufacturing cost of the noble metal ruthenium target material and meeting the application requirements of advanced process integrated circuit chips.

Description

Technical Field

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

[0002] Ruthenium thin films fabricated via magnetron sputtering on ruthenium targets possess advantages such as high-temperature resistance and low resistivity at the nanoscale, making them a core metal interconnect layer for advanced integrated circuit chips in magnetic storage, resistive switching, and other advanced processes. The prepared ruthenium films are typically several nanometers to tens of nanometers thick, placing extremely stringent requirements on the ruthenium target material: the target material usually needs fine grains and high density, with an average grain size of less than 10 μm and a relative density exceeding 99% to improve coating uniformity, reduce abnormal arcing during deposition, and decrease the number of generated microparticles, thereby improving chip yield. Due to ruthenium's high melting point of 2334℃, current ruthenium targets are primarily formed using powder metallurgy sintering processes, such as hot pressing or hot isostatic pressing. For hot pressing (HIP) sintering, ruthenium powder is first placed in a high-temperature resistant hot pressing mold such as isostatic graphite, and then hot pressing sintering is performed under vacuum or argon protection. Due to the strength limitations of graphite, the hot pressure is usually 15~50 MPa, thus requiring a higher sintering temperature to achieve high densification of the target material, but this easily leads to coarse grains and high-temperature carburization and impurities. For hot isostatic pressing (HIP), the hot pressure can reach over 100 MPa, thus allowing for a lower sintering temperature to achieve finer grains in the target material. The process typically involves: first, placing ruthenium powder in a metal sheath; second, evacuating and sealing the ruthenium powder inside the metal sheath; and then performing HIP sintering on the metal sheath containing the ruthenium powder. Throughout the entire HIP sintering process, the metal sheath maintains excellent airtightness, allowing the high-temperature, high-pressure argon gas medium used in HIP sintering to be applied to the ruthenium powder inside the sheath through the sheath, ultimately resulting in a highly dense ruthenium target blank. During the hot isostatic pressing (HIP) sintering process, the metal cladding and ruthenium powder shrink simultaneously. This results in the metal cladding and ruthenium target blank being tightly wrapped together, making subsequent removal of the cladding by machining or chemical etching extremely difficult, time-consuming, and prone to damaging the ruthenium target blank. Furthermore, the shrinkage of the ruthenium target blank is irregular, and metallurgical diffusion reactions easily occur at the interface between the cladding and the ruthenium target blank. This leads to ruthenium loss during cladding removal, which mixes into the cladding chips or chemical solutions. The ruthenium loss rate can typically reach over 5%, significantly reducing the yield of ruthenium target materials and thus increasing the manufacturing cost of precious metal ruthenium targets. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a ruthenium target and its preparation method. The ruthenium target prepared by the method of this invention has an average grain size of less than 5 μm, a relative density of over 99.5%, and the ruthenium target is easily separated from the metal sheath without sticking. The target yield reaches over 98%, thereby greatly reducing the manufacturing cost of the precious metal ruthenium target to meet the application requirements of advanced integrated circuit chips such as magnetic storage and resistive switching memory.

[0004] In a first aspect, the present invention provides a method for preparing a ruthenium target, comprising:

[0005] 1) Ruthenium powder is subjected to high-pressure cold molding to obtain ruthenium blank.

[0006] 2) The ruthenium blank is placed in a metal sheath made of stainless steel or low carbon steel, and then subjected to high-temperature vacuum degassing and welding to obtain a metal sheath containing the ruthenium blank.

[0007] 3) The metal cladding containing the ruthenium blank is subjected to two-stage hot isostatic pressing sintering; the pressure of the first stage sintering is 130~150MPa and the temperature is ≥1000℃; the pressure of the second stage sintering is 160~180MPa and the temperature of the second stage sintering is more than 150℃ higher than the temperature of the first stage sintering.

[0008] In this invention, ruthenium powder is subjected to high-pressure cold molding to prepare a ruthenium blank. The ruthenium blank is placed in a metal sheath and sheathed, and then subjected to a two-stage hot isostatic pressing sintering treatment under specific conditions. The first stage is a medium-high temperature holding pressure sintering at a temperature above 1000°C (pressure 130~150MPa). In this stage, the metal sheath material has good airtightness. The hot pressure is applied to the ruthenium blank inside the sheath through the sheath, so that the ruthenium blank can be sintered to a relative density of 95~96%. At the same time, the second stage is a high-temperature and high-pressure holding pressure sintering at a temperature at least 150°C higher than the first stage (pressure 160~180MPa). In this stage, the metal sheath material fails under high temperature and high pressure, and a through-crack is generated in the thickness direction of the sheath. However, the sheath does not melt into a liquid phase. The hot pressure is applied directly to the surface of the ruthenium sintered blank through the sheath, so that the ruthenium blank shrinks and densifies further. By optimizing the preparation process, metal cladding treatment, and two-stage hot isostatic pressing sintering conditions, the ruthenium target material prepared by this invention has an average grain size of less than 5 μm and a relative density of over 99.5%. Furthermore, the ruthenium target material and the metal cladding are easily separated and do not stick together, and the target material yield reaches over 98%. This greatly reduces the manufacturing cost of precious metal ruthenium targets and better meets the application requirements of advanced process integrated circuit chips such as magnetic storage and resistive switching storage.

[0009] Preferably, in step 1), the ruthenium powder has a particle size of 0.2~2μm and a purity of 5N. In this invention, by selecting high-purity, fine-particle-size powder raw materials, the sintering activity of the powder can be enhanced, which is beneficial for better preparation of high-purity, high-density, fine-grained ruthenium target materials.

[0010] Preferably, in step 1), the pressure of the high-pressure cold molding is 200~400MPa, and the relative density of the ruthenium blank is ≥50%. By selecting a regular mold and high-pressure molding, the dimensional accuracy and density of the blank can be improved, thereby achieving high-density and high-yield blank molding, which is beneficial to subsequent high-temperature sintering molding.

[0011] Preferably, in step 2), the wall thickness of the metal sheath is 0.5~2mm. More preferably, the carbon content of the low-carbon steel is less than 0.25%; the grade of the low-carbon steel preferably includes Q235, such as Q235A, Q235B, Q235C, etc. The grade of the stainless steel preferably includes 304. The metal sheath selected in this invention has good toughness, which facilitates the separation of the ruthenium billet from the sheath without adhesion, and is easy to weld and seal using argon arc welding, laser welding, etc., in an atmospheric environment. Throughout the entire hot isostatic pressing (HIP) sintering process, the metal sheath will not undergo severe liquid phase reaction with the target billet or the high-temperature resistant coating inside the sheath, nor will it melt into a liquid phase itself; moreover, at the HIP sintering temperature before the relative density of the target billet reaches 95~96%, the metal sheath has good high-temperature safety and airtightness; however, at the HIP sintering temperature after the relative density of the target billet reaches 96%, the metal sheath fails at high temperatures, producing through-cracks in the thickness direction of the sheath skin.

[0012] Preferably, in step 2), the inner wall of the metal sheath is provided with a high-temperature resistant insulating coating; the high-temperature resistant insulating coating does not undergo a liquid-phase reaction with the sheath or ruthenium, and the melting point of the high-temperature resistant insulating coating is higher than 1700℃. During the process of increasing the relative density of the ruthenium billet from 95-96% to over 99.5% in this invention, due to the failure of the stainless steel or low-carbon steel metal sheath and the presence of a high-temperature resistant insulating layer inside the sheath, the ruthenium billet is easily detached from the sheath and does not stick, thus facilitating subsequent sheath removal and improving the yield of the ruthenium target billet.

[0013] Further preferably, in step 2), the material of the high-temperature resistant isolation coating includes boron nitride, aluminum oxide, or yttrium oxide; the thickness of the high-temperature resistant isolation coating is 30~100μm.

[0014] Preferably, in step 2), the temperature of the high-temperature vacuum exhaust is 600~800℃.

[0015] Preferably, the high-temperature resistant insulating coating is prepared by methods including brushing or spraying.

[0016] Further preferably, the dimensional tolerance of the ruthenium blank and the inner cavity of the metal sheath is within ±0.2mm.

[0017] Preferably, in step 3), the sintering temperature of the first stage is 1000~1200℃, for example, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, etc., the pressure is 130~150MPa, for example, 130MPa, 135MPa, 140MPa, 145MPa, 150MPa, etc., and the heat and pressure holding time is 2~4h, for example, 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0018] Preferably, in step 3), the sintering temperature of the second stage is 1300~1400℃, for example, 1300℃, 1350℃, 1380℃, 1400℃, etc., the pressure is 160~180MPa, for example, 160MPa, 165MPa, 170MPa, 175MPa, 177MPa, 180MPa, etc., and the heat and pressure holding time is 1~2h, for example, 1h, 1.5h, 2h, etc.

[0019] In this invention, the ruthenium blank is subjected to two stages of hot isostatic pressing sintering with heat preservation and pressure preservation. In the first stage, the metal cladding material has good airtightness, and the thermal pressure is applied to the ruthenium blank inside the cladding through the cladding skin, so that the ruthenium blank can be sintered to a relative density of 95-96%. In the second stage, the metal cladding material fails under high temperature and high pressure, and a through-crack is generated in the thickness direction of the cladding skin. However, the cladding does not melt into a liquid phase, and the thermal pressure is applied directly to the surface of the sintered ruthenium blank through the cladding skin, so that the ruthenium blank material shrinks and densifies further. The effect is even better under the optimal temperature, pressure and time (the first stage sintering temperature is 1000~1200℃, the pressure is 130~150MPa, and the holding temperature and pressure are 2~4h; the second stage sintering temperature is 1300~1400℃, the pressure is 160~180MPa, and the holding temperature and pressure are 1~2h), which is more conducive to the preparation of high-quality ruthenium targets and improves the yield.

[0020] Preferably, the method further includes a step of removing the metal sheath, which includes removing the metal sheath after hot isostatic pressing sintering to obtain a ruthenium sintered target blank; preferably, the method further includes a post-processing step, which includes welding the ruthenium sintered target blank to a back plate and performing machining.

[0021] The ruthenium target material prepared by the method provided by this invention has an average grain size of less than 5 μm and a relative density of over 99.5%. Furthermore, the ruthenium target material is easy to separate from the metal cladding and does not stick together. The target material yield reaches over 98%, thereby greatly reducing the manufacturing cost of precious metal ruthenium target materials to meet the application requirements of advanced process integrated circuit chips such as magnetic storage and resistive switching storage.

[0022] Secondly, the present invention provides a ruthenium target material prepared by the above-described preparation method.

[0023] Preferably, the ruthenium target has an average grain size ≤ 5 μm, a relative density ≥ 99.5%, and a target yield ≥ 98%.

[0024] Further preferred, the ruthenium target has an average grain size ≤ 4.5 μm, a relative density ≥ 99.6%, the ruthenium target is easy to separate from the metal sheath and does not stick, and the target yield is ≥ 98.5%.

[0025] The beneficial effects of this invention are at least as follows: First, the ruthenium target material exhibits fine grains and high density. For conventional powder sintering processes of ruthenium targets, as the sintering temperature increases, it becomes easier to achieve high density. However, high sintering temperatures also lead to rapid grain growth, coarsening, and even abnormal growth of the target grains, making it extremely difficult to achieve both fine grains and high density in the ruthenium target material. This invention achieves both fine grains and high density in the ruthenium target material primarily through the following aspects: The initial ruthenium powder particle size is controlled at 0.2~2μm. The ruthenium powder is extremely fine with a large specific surface area, greatly enhancing the powder sintering activity, thereby reducing the sintering temperature and micro-grain size of the ruthenium target material. A hot isostatic pressing (HIP) sintering process under specific conditions is employed, and the extremely high thermal pressure facilitates rapid contact diffusion and densification of the ruthenium particles, significantly reducing the sintering temperature and shortening the sintering time, thus enabling the ruthenium target material to achieve both fine grains and high density. Secondly, conventional metal cladding does not suffer from high-temperature thermal cracking failure. During the entire hot isostatic pressing sintering process, the metal cladding and the built-in ruthenium powder or blank shrink synchronously. On the one hand, this causes the metal cladding and the ruthenium target blank to be tightly wrapped together, making it extremely difficult, time-consuming, and prone to damaging the ruthenium target blank when removing the cladding using machining or chemical etching methods. On the other hand, the ruthenium target blank tends to shrink irregularly, and metallurgical diffusion reactions easily occur at the interface between the cladding and the ruthenium target blank. As a result, ruthenium is easily lost during the cladding removal process, and it mixes into the cladding chips or chemical solution. The ruthenium loss rate can usually reach more than 5%, which greatly reduces the yield of ruthenium target materials and increases the manufacturing cost of precious metal ruthenium targets. This invention achieves high yield of ruthenium targets primarily through the following aspects: Combining the physical and mechanical properties of the metal cladding and ruthenium material at different hot isostatic pressing (HIP) sintering temperatures, the HIP sintering is divided into two holding and pressurizing stages: The first stage is medium-high temperature holding and pressurizing sintering, in which the stainless steel or low-carbon steel metal cladding material has good airtightness, and the thermal pressure is applied to the ruthenium blank inside the cladding through the cladding skin, allowing the ruthenium blank to be sintered to a relative density of 95-96%; the second stage is high temperature holding and pressurizing sintering, in which the metal cladding... Under high temperature and pressure, the material becomes embrittled due to grain boundary sliding migration, creep fracture, and chemical reactions with trace amounts of residual oxygen or nitrogen in the furnace. This leads to through-cracks in the thickness direction of the cladding, but the cladding does not melt into a liquid phase. High-pressure argon gas is then applied directly through these through-cracks to the surface of the ruthenium sintered billet. Since the relative density of the ruthenium sintered billet has reached 95-96%, and there are no through-pores on the surface, the billet can be pressure sintered without cladding, allowing it to further shrink and densify to over 99.5%. During the process of increasing the relative density of the ruthenium billet from 95-96% to over 99.5%, the metal cladding fails due to high temperature and pressure and stops shrinking, while the ruthenium billet continues to densify and shrink, completely detaching from the metal cladding. A significant detachment gap forms between them, which is highly beneficial for subsequent cladding removal.Furthermore, during the green blank forming process, a regular green blank with a relative density of over 50% is obtained through high-pressure cold molding at 200-400 MPa. This green blank is then placed within a regular metal sheath. This ensures that the ruthenium blank experiences relatively small and regular shrinkage and deformation during hot isostatic pressing (HIP), thus guaranteeing easy removal of the metal sheath and a regular dimensional appearance. Additionally, a high-temperature resistant insulating layer, such as boron nitride, aluminum oxide, or yttrium oxide, is coated inside the metal sheath. During HIP, especially in the first stage of heat and pressure holding, this ensures that diffusion reactions do not occur between the metal sheath and the ruthenium blank, thus facilitating the separation of the metal sheath from the ruthenium blank. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the manufacturing method of fine-grained, highly dense, and high-yield ruthenium sputtering targets provided in an embodiment of the present invention.

[0028] Figure 2 This is a schematic diagram showing the positions of the metal cladding, coating, and ruthenium blank before hot isostatic pressing sintering, as provided in an embodiment of the present invention.

[0029] Figure 3 This is a schematic diagram showing the positions of the metal cladding, coating, and ruthenium sintered billet during the medium-high temperature pressure holding sintering stage, as provided in an embodiment of the present invention.

[0030] Figure 4 This is a schematic diagram showing the positions of the metal cladding, coating, and ruthenium sintered billet during the high-temperature pressure sintering stage, as provided in an embodiment of the present invention. Detailed Implementation

[0031] 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.

[0032] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0033] Unless otherwise specified, the techniques or conditions described in the embodiments of this invention shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Devices, instruments, reagents, etc., without specified manufacturers, are all conventional products that can be purchased through legitimate channels. All experimental reagents and raw materials involved are commercially available products, and all reagents are analytical grade products.

[0034] In this embodiment of the invention, the blank is a square ruthenium blank, the stainless steel material grade is 304, and the low carbon steel grade is Q235.

[0035] Example 1

[0036] This embodiment provides a fine-grained, highly dense, and high-yield ruthenium target and its preparation method. See Figures 1-4 The details are as follows:

[0037] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 0.2μm.

[0038] 2) Blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold-pressing mold and cold-pressed at 300MPa to obtain a regular blank with a relative density of 55%. The dimensional tolerance of the blank and the inner cavity of the metal sheath is ±0.2mm.

[0039] 3) Vacuuming and Sealing of the Encasing: Place the ruthenium blank from step 2) into a regular stainless steel metal casing (0.5mm wall thickness), and then vacuum-vent and seal the casing at 700℃. Apply a 30μm thick boron nitride high-temperature resistant insulating coating to the inner wall of the casing, ensuring that it does not undergo liquid-phase reaction with either the casing or the ruthenium.

[0040] 4) Hot Isostatic Pressing (HIP): The metal cladding containing the ruthenium blank from step 3) is subjected to HIP, which consists of two holding and pressure stages: The first stage is medium-high temperature holding and pressure sintering, with a sintering temperature of 1000℃, a pressure of 130MPa, and a holding time of 4 hours. During this stage, the metal cladding material has good airtightness, and the thermal pressure is applied to the ruthenium blank inside the cladding through the cladding skin, allowing the ruthenium blank to be sintered to a relative density of 95~96%. The second stage is high temperature holding and pressure sintering, with a sintering temperature of 1300℃, a pressure of 160MPa, and a holding time of 1.5 hours. During this stage, the metal cladding material fails under high temperature and high pressure, and through-cracks are generated in the thickness direction of the cladding skin. However, the cladding does not melt into a liquid phase, and the thermal pressure is applied directly to the surface of the ruthenium sintered blank through the cladding skin, causing the ruthenium blank to shrink and densify further.

[0041] 5) Removal of the metal cladding: The metal cladding cover from step 4) of hot isostatic pressing (HIP) is removed, and then the ruthenium sintered target blank, now detached from the cladding, is taken out. There is a gap between the sintered blank and the cladding, making the cladding easy to remove.

[0042] 6) Welding to the backplate and machining the finished product: The ruthenium target blank from step 5) is welded to the backplate and then machined to finally produce a high-density ruthenium target. The average grain size of the ruthenium target is 2.5 μm, the relative density is 99.6%, and the yield is 99.2%.

[0043] Example 2

[0044] This embodiment provides a fine-grained, highly dense, and high-yield ruthenium target and its preparation method, as detailed below:

[0045] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 0.5μm.

[0046] 2) Blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold-pressing mold and cold-pressed at 200MPa to obtain a regular blank with a relative density of 52%. The dimensional tolerance of the blank and the inner cavity of the metal sheath is ±0.1mm.

[0047] 3) Vacuuming and Sealing of the Encasing: Place the ruthenium blank from step 2) into a regular low-carbon steel casing (1.0 mm wall thickness), and then vacuum-vent and seal the casing at 800℃. Apply a 50 μm thick alumina high-temperature resistant insulating coating to the inner wall of the casing, ensuring that it does not undergo a liquid-phase reaction with either the casing or the ruthenium.

[0048] 4) Hot Isostatic Pressing (HIP): The metal cladding containing the ruthenium blank from step 3) is subjected to HIP, which is divided into two holding and pressure stages: The first stage is medium-high temperature holding and pressure sintering, with a sintering temperature of 1100℃, a pressure of 140MPa, and a holding time of 3 hours. During this stage, the metal cladding material has good airtightness, and the hot pressure is applied to the ruthenium blank inside the cladding through the cladding skin, so that the ruthenium blank can be sintered to a relative density of 95~96%; The second stage is high temperature holding and pressure sintering, with a sintering temperature of 1300℃, a pressure of 160MPa, and a holding time of 1 hour. During this stage, the metal cladding material fails under high temperature and high pressure, and through-cracks are generated in the thickness direction of the cladding skin. However, the cladding does not melt into a liquid phase, and the hot pressure is applied directly to the surface of the ruthenium sintered blank through the cladding skin, causing the ruthenium blank to shrink and densify further.

[0049] 5) Removal of the metal cladding: The metal cladding cover from step 4) of hot isostatic pressing (HIP) is removed, and then the ruthenium sintered target blank, now detached from the cladding, is taken out. There is a gap between the sintered blank and the cladding, making the cladding easy to remove.

[0050] 6) Welding to the backplate and machining the finished product: The ruthenium target blank from step 5) is welded to the backplate and then machined to finally produce a high-density ruthenium target. The average grain size of the ruthenium target is 3.2 μm, the relative density is 99.7%, and the yield is 99.0%.

[0051] Example 3

[0052] This embodiment provides a fine-grained, highly dense, and high-yield ruthenium target and its preparation method, as detailed below:

[0053] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 1.5μm.

[0054] 2) Blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold-pressing mold and cold-pressed at 400MPa to obtain a regular blank with a relative density of 58%. The dimensional tolerance of the blank and the inner cavity of the metal sheath is ±0.2mm.

[0055] 3) Vacuuming and Sealing of the Encasing: Place the ruthenium blank from step 2) into a regular stainless steel metal casing (2mm wall thickness), and then vacuum-vent and seal the casing at 700℃. Apply a 100μm thick boron nitride high-temperature resistant insulating coating to the inner wall of the casing, which does not undergo liquid-phase reaction with the casing or the ruthenium.

[0056] 4) Hot Isostatic Pressing (HIP): The metal cladding containing the ruthenium blank from step 3) is subjected to HIP, which is divided into two holding and pressure stages: The first stage is medium-high temperature holding and pressure sintering, with a sintering temperature of 1200℃, a pressure of 150MPa, and a holding time of 2 hours. During this stage, the metal cladding material has good airtightness, and the hot pressure is applied to the ruthenium blank inside the cladding through the cladding skin, so that the ruthenium blank can be sintered to a relative density of 95~96%; The second stage is high temperature holding and pressure sintering, with a sintering temperature of 1350℃, a pressure of 175MPa, and a holding time of 2 hours. During this stage, the metal cladding material fails under high temperature and high pressure, and through-cracks are generated in the thickness direction of the cladding skin. However, the cladding does not melt into a liquid phase, and the hot pressure is applied directly to the surface of the ruthenium sintered blank through the cladding skin, causing the ruthenium blank to shrink and densify further.

[0057] 5) Removal of the metal cladding: The metal cladding cover from step 4) of hot isostatic pressing (HIP) is removed, and then the ruthenium sintered target blank, now detached from the cladding, is taken out. There is a gap between the sintered blank and the cladding, making the cladding easy to remove.

[0058] 6) Welding to the backplate and machining the finished product: The ruthenium target blank from step 5) is welded to the backplate and then machined to finally produce a high-density ruthenium target. The average grain size of the ruthenium target is 3.2 μm, the relative density is 99.6%, and the yield is 98.8%.

[0059] Example 4

[0060] This embodiment provides a fine-grained, highly dense, and high-yield ruthenium target and its preparation method, as detailed below:

[0061] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 2μm.

[0062] 2) Blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold-pressing mold and cold-pressed at 300MPa to obtain a regular blank with a relative density of more than 53%. The dimensional tolerance of the blank and the inner cavity of the metal sheath is within ±0.15mm.

[0063] 3) Vacuuming and Sealing of the Encasing: Place the ruthenium blank from step 2) into a regular low-carbon steel casing (1.5mm wall thickness), and then vacuum-vent and seal the casing at 600℃. Apply an 80μm thick alumina high-temperature resistant insulating coating to the inner wall of the casing, ensuring that it does not undergo a liquid-phase reaction with either the casing or the ruthenium.

[0064] 4) Hot Isostatic Pressing (HIP): The metal cladding containing the ruthenium blank from step 3) is subjected to HIP, which is divided into two holding and pressure stages: The first stage is medium-high temperature holding and pressure sintering, with a sintering temperature of 1200℃, a pressure of 150MPa, and a holding time of 4 hours. During this stage, the metal cladding material has good airtightness, and the hot pressure is applied to the ruthenium blank inside the cladding through the cladding skin, so that the ruthenium blank can be sintered to a relative density of 95~96%; The second stage is high temperature holding and pressure sintering, with a sintering temperature of 1400℃, a pressure of 180MPa, and a holding time of 2 hours. During this stage, the metal cladding material fails under high temperature and high pressure, and through-cracks are generated in the thickness direction of the cladding skin. However, the cladding does not melt into a liquid phase, and the hot pressure is applied directly to the surface of the ruthenium sintered blank through the cladding skin, causing the ruthenium blank to shrink and densify further.

[0065] 5) Removal of the metal cladding: The metal cladding cover from step 4) of hot isostatic pressing (HIP) is removed, and then the ruthenium sintered target blank, now detached from the cladding, is taken out. There is a gap between the sintered blank and the cladding, making the cladding easy to remove.

[0066] 6) Welding to the backplate and machining the finished product: The ruthenium target blank from step 5) is welded to the backplate and then machined to finally produce a high-density ruthenium target. The average grain size of the ruthenium target is 4.5 μm, the relative density is 99.8%, and the yield is 98.5%.

[0067] Example 5

[0068] This embodiment provides a fine-grained, highly dense, and high-yield ruthenium target and its preparation method, as detailed below:

[0069] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 1μm.

[0070] 2) Blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold-pressing mold and cold-pressed at 350MPa to obtain a regular blank with a relative density of more than 54%. The dimensional tolerance of the blank and the inner cavity of the metal sheath is within ±0.2mm.

[0071] 3) Vacuuming and Sealing of the Encasing: Place the ruthenium blank from step 2) into a regular stainless steel metal casing (0.5mm wall thickness), and then vacuum-vent and seal the casing at 700℃. Apply a 50μm thick boron nitride high-temperature resistant insulating coating to the inner wall of the casing, ensuring that it does not undergo a liquid-phase reaction with either the casing or the ruthenium.

[0072] 4) Hot Isostatic Pressing (HIP): The metal cladding containing the ruthenium blank from step 3) is subjected to HIP, which is divided into two holding and pressure stages: The first stage is medium-high temperature holding and pressure sintering, with a sintering temperature of 1000℃, a pressure of 130MPa, and a holding time of 2 hours. During this stage, the metal cladding material has good airtightness, and the hot pressure is applied to the ruthenium blank inside the cladding through the cladding skin, so that the ruthenium blank can be sintered to a relative density of 95~96%; The second stage is high temperature holding and pressure sintering, with a sintering temperature of 1380℃, a pressure of 177MPa, and a holding time of 1 hour. During this stage, the metal cladding material fails under high temperature and high pressure, and through-cracks are generated in the thickness direction of the cladding skin. However, the cladding does not melt into a liquid phase, and the hot pressure is applied directly to the surface of the ruthenium sintered blank through the cladding skin, causing the ruthenium blank to shrink and densify further.

[0073] 5) Removal of the metal cladding: The metal cladding cover from step 4) of hot isostatic pressing (HIP) is removed, and then the ruthenium sintered target blank, now detached from the cladding, is taken out. There is a gap between the sintered blank and the cladding, making the cladding easy to remove.

[0074] 6) Welding to the backplate and machining the finished product: The ruthenium target blank from step 5) is welded to the backplate and then machined to finally produce a high-density ruthenium target. The average grain size of the ruthenium target is 3.2 μm, the relative density is 99.6%, and the yield is 98.7%.

[0075] Example 6

[0076] This embodiment provides a fine-grained, highly dense, and high-yield ruthenium target and its preparation method, as detailed below:

[0077] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 1.5μm.

[0078] 2) Blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold-pressing mold and cold-pressed at 400MPa to obtain a regular blank with a relative density of more than 58%. The dimensional tolerance of the blank and the inner cavity of the metal sheath is within ±0.2mm.

[0079] 3) Vacuuming and Sealing of the Encasing: Place the ruthenium blank from step 2) into a regular stainless steel metal casing (2mm wall thickness), and then vacuum-vent and seal the casing at 800℃. Apply a 100μm thick yttrium oxide high-temperature resistant insulating coating to the inner wall of the casing, which does not undergo liquid-phase reaction with the casing or the ruthenium.

[0080] 4) Hot Isostatic Pressing (HIP): The metal cladding containing the ruthenium blank from step 3) is subjected to HIP, which is divided into two holding and pressure stages: The first stage is medium-high temperature holding and pressure sintering, with a sintering temperature of 1100℃, a pressure of 140MPa, and a holding time of 3 hours. During this stage, the metal cladding material has good airtightness, and the hot pressure is applied to the ruthenium blank inside the cladding through the cladding skin, so that the ruthenium blank can be sintered to a relative density of 95~96%; The second stage is high temperature holding and pressure sintering, with a sintering temperature of 1300℃, a pressure of 160MPa, and a holding time of 1 hour. During this stage, the metal cladding material fails under high temperature and high pressure, and through-cracks are generated in the thickness direction of the cladding skin. However, the cladding does not melt into a liquid phase, and the hot pressure is applied directly to the surface of the ruthenium sintered blank through the cladding skin, causing the ruthenium blank to shrink and densify further.

[0081] 5) Removal of the metal cladding: The metal cladding cover from step 4) of hot isostatic pressing (HIP) is removed, and then the ruthenium sintered target blank, now detached from the cladding, is taken out. There is a gap between the sintered blank and the cladding, making the cladding easy to remove.

[0082] 6) Welding to the backplate and machining the finished product: The ruthenium target blank from step 5) is welded to the backplate and then machined to finally produce a high-density ruthenium target. The average grain size of the ruthenium target is 3.5 μm, the relative density is 99.7%, and the yield is 99.1%.

[0083] Comparative Example 1

[0084] This comparative example provides a single-stage high-temperature pressure-holding sintering method for preparing ruthenium sputtering targets:

[0085] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 0.5μm.

[0086] 2) Green blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold pressing mold and cold-pressed at 200MPa to obtain a regular green blank with a relative density of 52%.

[0087] 3) Vacuuming and Sealing of the Encasing: The ruthenium blank from step 2) is placed inside a regular low-carbon steel casing (1.0 mm thick), and then the casing is vacuumed at 800℃ and sealed. The inner wall of the casing is coated with a high-temperature resistant alumina coating (50 μm thick) that does not react with the casing and the liquid ruthenium phase.

[0088] 4) Hot isostatic pressing sintering: The metal cladding containing the ruthenium blank in step 3) is subjected to hot isostatic pressing sintering. Instead of holding pressure sintering in the medium and high temperature stage, the temperature and pressure are directly increased from room temperature to high temperature holding pressure sintering. The sintering temperature is 1350℃, the pressure is 175MPa, and the temperature and pressure are held for 2 hours.

[0089] 5) Removal of the metal cladding: In step 4), the sintered metal cladding develops through-cracks along its thickness. However, the cladding tightly wraps around the ruthenium billet inside, and there is no gap between the sintered billet and the cladding, making the cladding difficult to remove. It is quite laborious to remove the metal cladding using a lathe, and the surface layer of the ruthenium billet is also removed along with the metal cladding chips. The average grain size of this comparative example is 2.5 μm, the relative density is 93.2%, and the yield of the ruthenium billet is 97.1%.

[0090] Comparative Example 2

[0091] This comparative example provides the first stage of ruthenium target material preparation using low-temperature and medium-pressure sintering:

[0092] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 0.5μm.

[0093] 2) Green blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold pressing mold and cold-pressed at 200MPa to obtain a regular green blank with a relative density of 52%.

[0094] 3) Vacuuming and Sealing of the Encasing: The ruthenium blank from step 2) is placed inside a regular low-carbon steel casing (1.0 mm thick), and then the casing is vacuumed at 800℃ and sealed. The inner wall of the casing is coated with a high-temperature resistant alumina coating (50 μm thick) that does not react with the casing and the liquid ruthenium phase.

[0095] 4) Hot isostatic pressing sintering: The metal cladding containing the ruthenium blank in step 3) is subjected to hot isostatic pressing sintering, which is divided into two heat and pressure holding stages: the first stage is medium and low temperature pressure holding sintering, with a sintering temperature of 900℃ and a pressure of 115MPa, and heat and pressure holding for 3 hours; the second stage is high temperature pressure holding sintering, with a sintering temperature of 1400℃ and a pressure of 180MPa, and heat and pressure holding for 2 hours.

[0096] 5) Removal of the metal cladding: In step 4), the sintered metal cladding develops through-cracks along its thickness. However, the cladding tightly wraps around the ruthenium billet inside, and there is no gap between the sintered billet and the cladding, making the cladding difficult to remove. It is quite laborious to remove the metal cladding using a lathe, and the surface layer of the ruthenium billet is also removed along with the metal cladding chips. The average grain size of this comparative example is 2.8 μm, the relative density is 94.1%, and the yield of the ruthenium billet is 96.5%.

[0097] Comparative Example 3

[0098] This comparative example provides ruthenium targets prepared by hot isostatic pressing sintering with a titanium metal cladding:

[0099] 1) Raw material: 99.999% pure ruthenium powder, with a particle size of 1.5μm.

[0100] 2) Blank forming: The ruthenium powder from step 1) is placed in a regular high-strength steel cold-pressing mold and cold-pressed at 400MPa to obtain a regular blank with a relative density of more than 58%. The dimensional tolerance of the blank and the inner cavity of the metal sheath is within ±0.2mm.

[0101] 3) Vacuuming and Sealing of the Encasing: Place the ruthenium blank from step 2) into a regular titanium metal casing (2mm wall thickness), and then vacuum-vent and seal the casing at 800℃. Apply a 100μm thick yttrium oxide high-temperature resistant insulating coating to the inner wall of the casing, which does not undergo liquid-phase reaction with the casing or the ruthenium.

[0102] 4) Hot isostatic pressing sintering: The metal cladding containing the ruthenium blank in step 3) is subjected to hot isostatic pressing sintering, which is divided into two heat and pressure holding stages: the first stage is medium-high temperature pressure holding sintering, with a sintering temperature of 1200℃, a pressure of 150MPa, and a heat and pressure holding time of 4h; the second stage is high temperature pressure holding sintering, with a sintering temperature of 1350℃, a pressure of 175MPa, and a heat and pressure holding time of 2h.

[0103] 5) Removal of the metal cladding: After sintering in step 4), the metal cladding has no visible through cracks. The cladding tightly wraps around the ruthenium billet inside. There is no gap between the sintered billet and the cladding. The cladding is difficult to remove. It takes considerable effort to remove the metal cladding using a lathe. In addition, the surface layer of the ruthenium billet is also removed along with the metal cladding chips. The average grain size of this comparative example is 5.2 μm, the relative density is 99.8%, and the yield of the ruthenium billet is 94.3%.

[0104] As can be seen from the performance results of ruthenium targets in Examples 1-6 and Comparative Examples 1-3, the ruthenium targets manufactured by the method of the present invention have the advantages of fine grains, high density and high yield, which reduces the manufacturing cost of the target and is beneficial to the uniformity of the coating thickness and the reduction of the number of micro particles in the subsequent target coating.

[0105] 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 ruthenium target, characterized in that, include: 1) Ruthenium powder is subjected to high-pressure cold molding to obtain ruthenium preform; 2) The ruthenium blank is placed in a stainless steel or low-carbon steel metal sheath, and subjected to high-temperature vacuum degassing and welding to obtain a metal sheath containing the ruthenium blank; the inner wall of the metal sheath is provided with a high-temperature resistant insulating coating; the high-temperature resistant insulating coating does not undergo liquid-phase reaction with the sheath or the ruthenium; the melting point of the high-temperature resistant insulating coating is higher than 1700℃, and the material of the high-temperature resistant insulating coating includes boron nitride, aluminum oxide or yttrium oxide; the thickness of the high-temperature resistant insulating coating is 30~100μm; 3) The metal cladding containing the ruthenium blank is subjected to two-stage hot isostatic pressing sintering; the pressure of the first stage sintering is 130~150MPa and the temperature is ≥1000℃; the pressure of the second stage sintering is 160~180MPa and the temperature of the second stage sintering is more than 150℃ higher than the temperature of the first stage sintering. The ruthenium target has an average grain size of ≤5μm, a relative density of ≥99.5%, and a target yield of ≥98%.

2. The preparation method according to claim 1, characterized in that, In step 1), the ruthenium powder has a particle size of 0.2~2μm and a purity of 5N; And / or, the pressure of the high-pressure cold molding is 200~400MPa; And / or, the ruthenium preform is circular or square in shape, and the relative density of the ruthenium preform is ≥50%.

3. The preparation method according to claim 1, characterized in that, In step 2), the wall thickness of the metal sheath is 0.5~2mm.

4. The preparation method according to any one of claims 1-3, characterized in that, In step 2), the temperature of the high-temperature vacuum exhaust is 600~800℃.

5. The preparation method according to any one of claims 1-3, characterized in that, In step 3), the sintering temperature of the first stage is 1000~1200℃, the pressure is 130~150MPa, and the holding time is 2~4h; And / or, in step 3), the sintering temperature of the second stage is 1300~1400℃, the pressure is 160~180MPa, and the holding time is 1~2h.

6. The preparation method according to any one of claims 1-3, characterized in that, It also includes a step of removing the metal cladding, which includes removing the metal cladding after hot isostatic pressing sintering to obtain a ruthenium sintered target blank; And / or, may include a post-processing step, which includes welding the ruthenium sintered target blank to the back plate and machining it.

7. A ruthenium target, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

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