Al-Sc alloy, sputtering target, and method for solidifying it.

Abstract

A method for manufacturing an aluminum-scandium alloy sputtering target, wherein Sc x Al 1-x A method comprising the steps of atomizing to form a powder, where x is in the range of 0.05 to 0.5, and solidifying the powder to form a target having a microstructure characterized by an average particle size of up to 50 microns. An aluminum-scandium alloy sputtering target comprising one or more Al-Sc intermetallic phases comprising Al-Sc intermetallic particles, wherein the average Al-Sc intermetallic particle size is up to 50 microns.

Description

[Technical Field]

[0001] Claim of priority

[0001] This application claims priority to U.S. Provisional Application No. 63 / 497,406, filed on April 20, 2023, the entire contents and disclosures thereof, which are incorporated herein by reference.

[0002]

[0002] This disclosure relates to a sputtering target and a method for manufacturing the same. In particular, the method uses powder in a solidification process to produce a durable aluminum-scandium alloy sputtering target suitable for forming a metal film or nitride film. In one embodiment, the durable sputtering target is less prone to cracking. [Background technology]

[0003]

[0003] Aluminum scandium nitride (Al x Sc 1-x Aluminum scandium nitride (AlScN) is attracting attention for its use in fabricating thin-film piezoelectric materials for various applications. Specifically, aluminum scandium nitride (AlScN) thin films produced by reactive sputtering from Al-Sc alloy targets are useful as piezoelectric materials in electroacoustic applications. For example, AlScN films are used in the manufacture of bulk acoustic wave (BAW) filters that enable 5G communication. Conventional methods for manufacturing these piezoelectric thin films use reactive sputtering deposition. The sputtering target is usually a metal or metal alloy and consists of the material to be sputtered. The sputtering target and substrate are placed in close proximity to each other in a chamber, and charged particles or ions are irradiated onto the target. High-energy ions cause a portion of the sputtering target to peel off and redeposit onto the substrate. Sputtering has the advantages of allowing control of the film composition, control of residual stress within the film, high-speed deposition of thin films, and easy controlled heating of the substrate. There is already a wealth of experience in manufacturing thin films using this method.

[0004]

[0004] The properties of the resulting thin film depend heavily on the uniform deposition of the Al-Sc alloy. Therefore, significant requirements are placed on the properties of the sputtering target and the alloy. Al-Sc alloy systems present challenges in sputtering target manufacturing because they contain multiple brittle intermetallic phases and are prone to segregation. The piezoelectric response of the thin film strongly depends on the scandium content in the film, so the overall morphology, microstructure, and chemical composition of scandium in the sputtering target are extremely important.

[0005]

[0005] Conventionally, targets containing aluminum-scandium alloys have physical / mechanical performance defects such as non-uniform microstructure, low-density regions, and / or defects that cause cracking, which can cause arcing and / or particle formation during sputtering, leading to reduced yield and shortened target life. [Overview of the project] [Problems that the invention aims to solve]

[0006]

[0006] Considering known alloys and sputtering targets, there is a need for a simple powder solidification method to produce Al-Sc alloy sputtering targets that provide a uniform and fine microstructure while also possessing high density, hardness, and fracture toughness. Targets having a uniform and fine microstructure as described herein satisfy the requirement for targets that minimize the sputtering arc generated during magnetron sputtering and improve performance. [Means for solving the problem]

[0007]

[0007] In some aspects, the techniques described herein relate to methods for manufacturing aluminum-scandium alloy sputtering targets. The method is Sc x Al 1-xA step of atomizing to form a powder, where x ranges from 0.05 to 0.5, is included. The method further includes a step of consolidating the powder to form a target having a microstructure characterized by an average particle size of up to 50 microns.

[0008]

[0008] In some embodiments, the technology described herein is a method for manufacturing an aluminum-scandium alloy sputtering target, where Sc x Al 1-x A step of atomizing to form a powder, where x ranges from 0.25 to 0.45, and a step of consolidating the powder to form a target having an average Al-Sc intermetallic particle size of up to 50 microns. Consolidation may include heating to 900°C to 1200°C under pressure by at least one of spark plasma sintering, ultra-high pressure sintering, hot pressing, inert gas hot pressing, and vacuum hot pressing.

[0009]

[0009] In some embodiments, the technology described herein relates to an aluminum-scandium alloy sputtering target, including one or more Al-Sc intermetallic phases (including Al-Sc intermetallic particles), and having an average Al-Sc intermetallic particle size of up to 50 microns.

[0010]

[0010] A further understanding of the nature and advantages of the disclosed technology can be obtained by referring to the remainder of this specification and the drawings.

Brief Description of the Drawings

[0011] [Figure 1A]

[0011] A diagram showing the relationship between Sc content and piezoelectric coefficient. [Figure 1B]

[0012] A diagram showing the relationship between Sc content and mixing enthalpy. [Figure 2]

[0013] A schematic diagram of a centrifugal gas atomization system. [Figure 3]

[0014] This figure shows the particle size distribution of 30% GA powder. [Figure 4]

[0015] These are SED-SEM micrographs of atomized powder at low and high magnification. (a, d) GA 5%, (b, e) GA 30%, (c, f) GA 50%. [Figure 5]

[0016] These are cross-sectional OM micrographs (top) and BSE-SEM micrographs (bottom) of atomized powders (a, d) GA 5%, (b, e) GA 30%, and (c, f) GA 50%. [Figure 6]

[0017] This figure shows the phase diagram of an Al-Sc binary system. [Figure 7]

[0018] This is a cross-sectional BSE-SEM image of a GA Sc30% particle with a central pore. The inset shows the cooling rate calculated using DAS. [Figure 8]

[0019] This figure shows the X-ray diffraction patterns with Miller indices for GA Sc5%, Sc30%, and Sc50% powders. [Figure 9]

[0020] These are microscopic images of a comparative casting (Sc6%) and HP (GA Sc5%). [Figure 10]

[0021] This figure shows a BSE-SEM image of HP GA Sc50% and the corresponding EDS elemental mapping. [Figure 11]

[0022] This figure shows a DTA thermogram of GA30% powder. [Figure 12]

[0023] These are OM microscope images of samples HP 1-4#. The brown phase is Al2Sc, and the white matrix is ​​Al3Sc. [Figure 13]

[0024] These are optical microscope and SEM images of HP1# after heat treatment at 1200°C and water cooling. The phases shown were confirmed by EDS. [Figure 14]

[0025] This figure shows the X-ray diffraction patterns of 30%Sc samples. a) GA powder, b) casting, c) 1100℃ HP, d) HP + 1200℃ heat treatment. [Figure 15]

[0026] This figure shows time-dependent plots of process temperature, DC current, ram pressure, and ram position. [Figure 16]

[0027] These are optical microscope images of SPS samples #1-4. The brown phase is Al2Sc, and the white matrix phase is Al3Sc. [Figure 17]

[0028] This is an optical microscope image of a used SPS target showing the phase structure according to the embodiments of this specification. [Figure 18]

[0029] This is an optical microscope image of a used casting comparison target. [Figure 19]

[0030] This is an electron backscatter diffraction (EBSD) micrograph of a used SPS target showing a granular structure according to the embodiments of this specification. [Figure 20]

[0031] This is an EBSD micrograph of a used casting comparison target. [Figure 21]

[0032] Optical microscope images of Vickers indentations on polished surfaces of Al-30%Sc. a) Comparative cast Al3Sc phase, b) Comparative cast Al2Sc phase, c) HP3#, and d) SPS1#. White phase is Al3Sc, brown phase is Al2Sc. Working load = 1 kg. Note the difference in scale bar length. [Figure 22]

[0033] This figure shows the SED-SEM fracture surface of sample SPS 4#. a) shows the cleavage step and river pattern at low magnification, b) shows the cleavage step and river pattern at high magnification, and c) shows a micrograph of SPS + quenched crack. [Figure 23]

[0034] This figure shows a) a comparative casting, b) SPS4#, and c) used targets of HP3#. [Figure 24]

[0035] These are optical microscope images of an SPS4# target after 12 hours of sputtering. a) Inside the track area, b) Outside the track area. [Figure 25]

[0036] These are optical microscope images of used targets. A) Comparative casting, b) SPS4#, c) HP3#. [Figure 26]

[0037] This figure shows the X-ray diffraction pattern of an HP AlSc 35% target according to the embodiments of this specification. [Figure 27]

[0038] This figure shows the X-ray diffraction pattern of a cast 35% Sc comparison target. [Figure 28]

[0039] This is an optical microscope image of a cast 35% Sc comparison target. [Modes for carrying out the invention]

[0012] introduction

[0040] As described above, conventional Al-Sc alloy sputtering targets suffer from problems due to non-uniform microstructure and / or defects (e.g., cracks) resulting from issues related to the brittle (intermetallic) phase common to Al-Sc alloys.

[0013]

[0041] The disclosed methods, when combined synergistically, have been found to provide a uniform and fine microstructure with desired high hardness and fracture toughness. To obtain the desired microstructure, an Al-Sc alloy is atomized to form a powder, which is then solidified. Surprisingly, in a target with a scandium content of approximately 30 atomic percent, atomization was found to predominantly produce a preferred phase such as Al3Sc rather than Al2Sc (contrary to the phases predicted from existing binary Al-Sc phase diagrams). Advantageously, the atomized powder herein contains spherical particles with a fine average size and a narrow particle size distribution. The method herein further includes solidifying the atomized powder by hot pressing and / or discharge plasma sintering to form a dense sintered sputtering target with high fracture toughness and a uniform phase distribution.

[0014]

[0042] The sputtering target manufactured by the method of this specification can be used to deposit a thin film on a substrate. The piezoelectric properties of individual devices on the substrate largely depend on the local stoichiometric composition of the films contained within the individual devices. Therefore, the distribution of scandium and / or scandium-containing phases throughout the entire Al-Sc sputtering target should be as fine and uniform as possible. This is important because if the amount of scandium sputtered from the target varies over the target lifetime, the piezoelectric properties of the deposited film will vary over the target lifetime, leading to variations in device performance and a reduction in product yield. Furthermore, certain intermetallic phases (e.g., Al3Sc) are preferred over other phases (e.g., Al2Sc) and are known to impart certain favorable properties such as fracture toughness (e.g., crack resistance). Therefore, phases uniformly distributed within the microstructure of the target are also necessary to provide a long-lived and high-performance (crack-resistant, minimal arcing behavior, minimal atomization) target. The processing of the sputtering target, as well as its properties and characteristics, will be discussed below.

[0015] Piezoelectric Materials for Electroacoustic Applications

[0043] One of the piezoelectric materials for electroacoustic applications is aluminum nitride (AlN). However, AlN-based devices have a low piezoelectric coefficient d 33 = 5.5 pC / N and a limited electromechanical coupling of 7%. These properties are significantly improved by adding scandium (Sc) to wurtzite-structured AlN. Adding Sc to AlN has been shown to increase the piezoelectric coefficient d 33 by up to 400% (Figure 1A). Furthermore, the electromechanical coupling of the Al 1-x Sc x N material is predicted to increase by 200% at a Sc concentration of x = 0.3. Piezoelectric AlScN maintains a hexagonal wurtz structure similar to c-axis-oriented AlN up to x = 0.5 (Figure 1B), so the maximum doping amount of Sc into Al 1-x Sc x N can reach 50%.

[0016]

[0044] AlScN thin films are typically manufactured by reactive sputtering from AlSc alloy targets. Essential properties required of all AlScN thin films are similar: the deposit must be chemically uniform, have a consistent metallic structure, uniform thickness, and adequately cover all features on the substrate. The sputtering performance of the AlSc target must be predictable and consistent. Performance should not vary significantly throughout the target's lifetime, and the reliability of the sputtering should not differ from target to target. The AlSc sputtering target itself is primarily manufactured by casting and refers to the bulk material deposited on the substrate. The quality of the deposited film is directly influenced by the quality of the cast target. Common defects include porosity and heterogeneity in both composition and microstructure, resulting from the wide solidification temperature range (ΔT up to 640°C) and the large melting point difference between Sc and Al in Al-Sc systems (Sc content <25 atomic%, see Figure 6). Impurities and oxides are also common concerns. The composition of these targets significantly impacts the success of the sputtering process and, consequently, the overall usability of the filter itself. Impurities are harmful components often found in target materials and tend to weaken the piezoelectric effect of Al-Sc alloys. Another defect commonly found in target materials is porosity. During sputtering, porosity not only hinders a uniform deposition rate but can also cause particle formation.

[0017]

[0045] Powder metallurgy (PM) is a suitable alternative route for manufacturing large (diameter) targets, potentially minimizing porosity and non-uniformity of composition and microstructure, and potentially reducing the overall cost of the final target produced by conventional ingot metallurgy.

[0018]

[0046] However, controlling oxygen is a major challenge in powder sintering. Elemental powders of Al and Sc, as well as aluminum-scandium intermetallic compounds, are highly reactive, resulting in easy oxidation of the particle surface and the formation of a surface oxide film, posing a technical challenge. Hot pressing under a vacuum or hydrogen atmosphere can solve the problem to some extent, but if stable Al2O3 or Sc2O3 oxides are formed, it cannot be expected that most of the oxygen will be removed by vacuum or hydrogen. In recent years, SPS technology has emerged as a new means of overcoming the constraints of surface films. In this method, a high amperage DC current and uniaxial pressure are typically applied simultaneously to compress and sinter the powder. Unlike conventional sintering methods, the SPS process has a fast heating rate and a low sintering temperature, thus suppressing coarsening of the microstructure. It has been demonstrated that surface oxides at interparticle contact points can be reduced by SPS. The presence of a semi-continuous network of residual oxide phases in the sintered product is undesirable as it can adversely affect ductility.

[0019] Experimental method

[0047] This specification includes some details regarding illustrative experimental methods. These examples are not intended to be limiting and are not intended to limit.

[0020]

[0048] Microstructure analysis. In some cases, the microstructure and morphology of the powder are evaluated using either an optical microscope (OM, Keyence VHX-970F) or a scanning electron microscope (SEM, JEOL JSM-IT500). Cross-sections of GA powder and pressed samples are mounted, polished, and finally polished with a 1200-grit silicon carbide disk, then progressively polished with cloth pads and 9, 6, 3, and 1 micron diamond suspensions, and finally finished with a 0.06 micron colloidal silica suspension. Microstructure analysis is also performed using electron backscatter diffraction (EBSD) with the JEOL IT800. The microstructure can be characterized by the present phases and / or average particle size. The present phases (e.g., intermetallic Al-Sc phase) can be determined by a combination of microscopic images, image analysis, and X-ray diffraction. Average particle size is determined by ASTM E112-13.

[0021]

[0049] Hardness. Hardness is measured using a Wilson VH1202 Vickers hardness tester with loads of 0.05 kg, 0.3 kg, 1 kg, and 2 kg. The average hardness can be determined from five measurements. Fracture toughness can be calculated from the indentation dimensions and crack length measurements at the indentation tip, according to the ASTM E384 standard test method.

[0022]

[0050] Electrical conductivity. Eddy current conductivity can be tested using a Sigmascope SMP350-Fisher.

[0051] Phase transition. Differential thermal analysis (DTA) can be performed using the Perkin Elmer DTA system 1700 under an Ar atmosphere, from room temperature to 1250°C, at a constant heating and cooling rate of 20°C / min.

[0023]

[0052] Density. The density of the sample can be measured by hydrostatic metering in distilled water using an analytical balance. The accuracy of the density is ±0.02 g / cc.

[0053] X-ray diffraction. Phase analysis and microstructure characterization can be determined in the 2θ range of 20 to 75° by X-ray diffraction (XRD) using Cu-Kα rays (λ=0.15406 nm). An angular step size of 0.02° and a count time of 11 seconds / step can be used. Since all the phases involved, Al(fcc), Al3Sc(L12), Al2Sc(C15), and AlSc(B2), have a cubic structure, the following equation for the d-plane spacing holds.

[0024]

number

[0025]

number

[0026]

number

[0027] method

[0054] This disclosure relates to a method for manufacturing an Al-Sc alloy sputtering target. x Al 1-x The process includes the steps of atomizing to form a powder, where x is in the range of 0.05 to 0.5, and solidifying the powder to form a target.

[0028]

[0055] Atomizing. Atomizing can be carried out by centrifugal helium atomization, as detailed in the following examples. Atomizing may include a powder consisting of one or more phases. In the case of Al-30%Sc, in some embodiments, atomizing may include a powder having an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5. The methods herein include cases where x is in the range of 0.25 to 0.33, and atomizing includes the powder having a higher Al3Sc / (Al3Sc+Al2Sc) ratio than the casting, as detailed in the following examples. In some embodiments where x is in the range of 0.25 to 0.33, the powder includes an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5, for example, at least 0.55, at least 0.60, at least 0.62, at least 0.63, at least 0.64, or at least 0.65. More specifically, and unexpectedly (considering the phase diagram in Figure 6), when x is in the range of 0.29 to 0.33, the powder contains at least an Al3Sc / (Al3Sc+Al2Sc) ratio of 0.5. In other words, the atomized powder contains more Al3Sc than Al2Sc. Unless otherwise specified, the ratio can be determined based on the integrated XRD peak intensity of the Al-Sc intermetallic phase. As understood herein, atomizing a powder may further involve milling and / or crushing the powder to reduce its particle size before solidification.

[0029]

[0056] Solidification. Solidification includes inert gas or vacuum hot pressing and / or discharge plasma sintering, as detailed in the following embodiments. In the case of Al-30%Sc, solidification may include a target having an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5 (illustrated in Table 6 below). In some embodiments, the target has an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5, e.g., at least 0.55, at least 0.60, at least 0.62, at least 0.63, at least 0.64, or at least 0.65. In some embodiments where x is in the range of 0.25 to 0.33, the target has an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5, e.g., at least 0.55, at least 0.60, at least 0.62, at least 0.63, at least 0.64, or at least 0.65. More specifically, if x is in the range of 0.29 to 0.33, the target will contain an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5.

[0030]

[0057] Hot pressing may involve heating at a specific temperature, time, and pressure (e.g., sintering to achieve densification). Hot pressing may include inert gas hot pressing (IGHP) and hot isostatic pressing (HIP). In some embodiments, hot pressing is performed at temperatures between 900°C and 1250°C, e.g., 1000°C to 1225°C, 1050°C to 1250°C, or 1100°C to 1250°C. With respect to the lower limit, hot pressing can be performed at temperatures of at least 900°C, e.g., at least 950°C, at least 1050°C, or at least 1100°C. With respect to the upper limit, hot pressing can be performed at temperatures up to 1250°C, e.g., up to 1225°C, up to 1200°C, or up to 1150°C.

[0031]

[0058] In some embodiments, the hot pressing is performed for 1 to 8 hours, for example, 1 to 4 hours, 2 to 6 hours, or 3 to 5 hours. Lowerly, the hot pressing can be performed for at least 1 hour, for example, at least 2 hours, or at least 3 hours. Upperly, the hot pressing can be performed for up to 8 hours, for example, up to 6 hours, up to 5 hours, or up to 4 hours. In certain embodiments, the hot pressing is performed for 4 hours.

[0032]

[0059] In some embodiments, the hot press is performed at a pressure of 10 MPa to 60 MPa, for example, 10 MPa to 50 MPa, or 15 MPa to 45 MPa. Regarding the lower limit, the hot press can be performed at a pressure of at least 10 MPa, for example, at least 15 MPa, or at least 25 MPa. Regarding the upper limit, the hot press can be performed at a pressure of up to 60 MPa, for example, up to 50 MPa, up to 45 MPa, or up to 35 MPa. In a particular embodiment, the hot press is performed at a pressure of 15 MPa. In another embodiment, the hot press is performed at a pressure of 45 MPa.

[0033]

[0060] Hot pressing can be performed in an inert atmosphere, such as Ar gas.

[0061] Discharge plasma sintering may involve heating at a specific temperature, time, and pressure (e.g., sintering that results in densification). Ultra-high pressure sintering can also be used. In some embodiments, discharge plasma sintering is performed at temperatures of 900°C to 1250°C, e.g., 900°C to 1200°C, 950°C to 1150°C, 1000°C to 1200°C, or 1000°C to 1100°C. With respect to the lower limit, discharge plasma sintering can be performed at temperatures of at least 900°C, e.g., at least 950°C, at least 1000°C, at least 1050°C, or at least 1100°C. With respect to the upper limit, discharge plasma sintering can be performed at temperatures up to 1250°C, e.g., up to 1100°C, up to 1150°C, or up to 1100°C.

[0034]

[0062] In some embodiments, the discharge plasma sintering is performed for 1 minute to 60 minutes (1 hour), for example, 5 minutes to 60 minutes, 10 minutes to 40 minutes, or 15 minutes to 30 minutes. Regarding the lower limit, the discharge plasma sintering can be performed for at least 1 minute, for example, at least 5 minutes, at least 10 minutes, or at least 15 minutes. Regarding the upper limit, the discharge plasma sintering can be performed for up to 1 hour, for example, up to 40 minutes or up to 30 minutes. In certain embodiments, the discharge plasma sintering is performed for 10 minutes, or 22 minutes, or 40 minutes.

[0035]

[0063] In some embodiments, discharge plasma sintering is performed at a pressure of 35 MPa to 75 MPa, for example, 45 MPa to 65 MPa. Regarding the lower limit, discharge plasma sintering can be performed at a pressure of at least 35 MPa, for example, at least 45 MPa, or at least 55 MPa. Regarding the upper limit, discharge plasma sintering can be performed at a pressure of up to 75 MPa, for example, up to 65 MPa, or up to 55 MPa. In certain embodiments, discharge plasma sintering is performed at a pressure of 45 MPa. In other embodiments, discharge plasma sintering is performed at a pressure of 55 MPa. In yet another embodiment, discharge plasma sintering is performed at a pressure of 65 MPa.

[0036]

[0064] Discharge plasma sintering can be carried out in an inert atmosphere, such as in Ar gas, or in a vacuum, or in a forming gas. In certain embodiments, the method herein involves solidifying a powder to form an aluminum-scandium alloy sputtering target by discharge plasma sintering at a temperature of 1000°C to 1200°C; a time of 1 minute to 60 minutes; and a pressure of 35 MPa to 75 MPa, one or more of these conditions.

[0037]

[0065] Target composition. In some embodiments, the Al-Sc target contains 5 to 50 atomic percent scandium and 50 to 95 percent aluminum (and optionally other elements). For example, Sc x Al 1-xIn this example, if x is 0.05, it means the alloy contains 5 atomic percent scandium and 95 atomic percent aluminum. x Al 1-x In this example, if x is 0.3, it means the alloy contains 30 atomic percent scandium and 70 atomic percent aluminum. In yet another example, Sc x Al 1-x In this case, if x is 0.5, it means the alloy contains 50 atomic percent scandium and 50 atomic percent aluminum. The detailed composition will be described later. The composition of the atomized, pulverized and / or milled powder determines the target composition.

[0038]

[0066] Overall, the manufacturing method is Sc x Al 1-x The Al-Sc target includes, where x is in the range of 0.05 to 0.5, for example, x is in the range of 0.05 to 0.50, 0.10 to 0.50, 0.08 to 0.45, 0.15 to 0.45, 0.25 to 0.45, 0.20 to 0.40, 0.05 to 0.10, 0.10 to 0.15, 0.15 to 0.20, 0.20 to 0.25, 0.25 to 0.30, 0.30 to 0.35, 0.35 to 0.40, 0.40 to 0.45, or 0.45 to 0.50. In certain embodiments, with respect to the lower limit, the Al-Sc sputtering target may include x = at least 0.05, e.g., at least 0.08, at least 0.10, at least 0.15, at least 0.20, at least 0.25, at least 0.30, at least 0.35, at least 0.40, or at least 0.45. With respect to the upper limit, the Al-Sc sputtering target may include x = up to 0.5, e.g., up to 0.50, up to 0.45, up to 0.40, up to 0.35, up to 0.30, up to 0.25, up to 0.20, up to 0.15, or up to 0.10. In some embodiments, x is equal to 0.30; or x is equal to 0.35; or x is equal to 0.38; or x is equal to 0.42.

[0039]

[0067] Overall, the disclosed Al-Sc alloy sputtering targets, in some embodiments, contain scandium in amounts of 5 to 50 atoms, for example, 10 to 50 atoms, 5 to 45 atoms, 8 to 45 atoms, 15 to 45 atoms, 25 to 45 atoms, 20 to 40 atoms, 5 to 10 atoms, 10 to 15 atoms, 15 to 20 atoms, 20 to 25 atoms, 25 to 30 atoms, 30 to 35 atoms, 35 to 40 atoms, 40 to 45 atoms, or 45 to 50 atoms.

[0040]

[0068] Regarding the lower limit, the Al-Sc sputtering target may contain at least 5 atomic percent of scandium, for example, at least 8 atomic percent, at least 10 atomic percent, at least 15 atomic percent, at least 20 atomic percent, at least 25 atomic percent, at least 30 atomic percent, at least 35 atomic percent, at least 40 atomic percent, or at least 45 atomic percent of scandium. Regarding the upper limit, the sputtering target may contain up to 50 atomic percent of scandium, for example, up to 45 atomic percent, up to 40 atomic percent, up to 35 atomic percent, up to 30 atomic percent, up to 25 atomic percent, up to 20 atomic percent, up to 15 atomic percent, or up to 10 atomic percent of scandium.

[0041]

[0069] Overall, the disclosed Al-Sc alloy sputtering targets having the above scandium content include, in some embodiments, the remaining aluminum, for example, 50 to 95 atomic percent of aluminum. With respect to the lower limit, the Al-Sc sputtering target may contain at least 50 atomic percent of aluminum, for example, at least 55 atomic percent, at least 60 atomic percent, at least 65 atomic percent, at least 70 atomic percent, at least 75 atomic percent, at least 80 atomic percent, at least 85 atomic percent, or at least 90 atomic percent of aluminum. With respect to the upper limit, the sputtering target may contain up to 95 atomic percent of aluminum, for example, up to 90 atomic percent, up to 85 atomic percent, up to 80 atomic percent, up to 75 atomic percent, up to 70 atomic percent, up to 65 atomic percent, up to 60 atomic percent, or up to 55 atomic percent of aluminum.

[0042] Target microstructure

[0070] The disclosed Al-Sc alloy sputtering targets have a microstructure characterized by a fine microstructure and a uniform phase distribution. Both of these properties result in a durable sputtering target with high fracture toughness and resistance to cracking. The fine microstructure is shown in the examples herein, with an average grain size of up to 10 microns for the intermetallic phase. Importantly, the grain size of the fine microstructure of targets manufactured by the method herein is 10 times finer than that of conventional cast targets.

[0043]

[0071] The aluminum-scandium alloy sputtering targets disclosed herein may have an average particle size in the range of 0.1 microns to 10 microns. In some embodiments, the aluminum-scandium alloy sputtering targets are characterized by having an average particle size in the range of 0.1 microns to 10 microns, for example, 0.5 microns to 10 microns, 1 micron to 10 microns, 1 micron to 5 microns, or 2 microns to 4 microns. In some embodiments, the aluminum-scandium alloy sputtering targets disclosed herein may have an average particle size in the range of 1 micron to 5 microns, or 2 microns to 4 microns.

[0044]

[0072] Regarding the lower limit, an aluminum-scandium alloy sputtering target can be characterized by having an average particle size of at least 0.1 microns, e.g., at least 0.5 microns, at least 1 micron, or at least 2 microns. Regarding the upper limit, an aluminum-scandium alloy sputtering target can be characterized by having an average particle size of up to 10 microns, e.g., up to 8 microns, up to 6 microns, or up to 5 microns.

[0045]

[0073] Furthermore, in the aluminum-scandium alloy sputtering targets of the methods described herein, the distribution of the intermetallic phases is uniform. In the examples described herein, the intermetallic phases are uniformly distributed, and the fine microstructure is evident. In some embodiments, the first Al-Sc intermetallic phase and the second Al-Sc intermetallic phase are each distributed in phase regions with a diameter of up to 10 microns. The uniformly distributed phases are observed in the microstructure by optical microscopy and / or scanning electron microscopy and image analysis. The intermetallic phases may be interconnected, in which case, if the phase regions are multi-grained and non-spherical, the region size is estimated as the equivalent diameter of a sphere.

[0046]

[0074] The aluminum-scandium alloy sputtering targets disclosed herein may have a first Al-Sc intermetallic phase and a second Al-Sc intermetallic phase, each distributed in phase regions with a diameter of up to 10 microns. In some embodiments, the aluminum-scandium alloy sputtering targets are characterized by having a uniform distribution of intermetallic phases in the range of 1 to 20 microns, for example, 1 to 10 microns, 4 to 10 microns, or 5 to 8 microns. In some embodiments, the aluminum-scandium alloy sputtering targets herein may have intermetallic phases distributed in phase regions with a diameter of up to 10 microns.

[0047]

[0075] The aluminum-scandium alloy sputtering targets disclosed herein, having 25% or more scandium, may include one or more Al-Sc intermetallic phases. In some embodiments, the target includes Al3Sc and Al2Sc. In some embodiments, the target consists of Al3Sc and Al2Sc. In some embodiments, the target includes AlSc and Al2Sc. In some embodiments, the target consists of AlSc and Al2Sc. In some embodiments, there are no phases other than the Al-Sc intermetallic phase.

[0048]

[0076] The targets described herein may be Al2O3-free or substantially Al2O3-free. The targets described herein may be free of free aluminum (Al)-free or substantially Al2O3-free. "Free of or substantially Al2O3" means that no aluminum oxide or metal aluminum is added and is explicitly avoided. In some cases, trace amounts of aluminum oxide or aluminum are present, e.g., less than 5% by weight of the total target weight, less than 3% by weight of the total target weight, or less than 1% by weight of the total target weight. In some cases, the amount of aluminum oxide or aluminum is below the detection limit, e.g., less than 3% by weight as measured by X-ray diffraction.

[0049]

[0077] The aluminum-scandium alloy sputtering targets disclosed herein can be characterized by a microstructure that includes an isotropic crystallographic structure. This isotropic texture can be determined by X-ray diffraction. In other words, the grain structure in the microstructure of the disclosed targets is random, and no specific planes are identified during analysis. For comparison, cast targets, as shown in the examples, have organized grains and exhibit anisotropy.

[0050] Characteristics of atomized powders

[0078] Powder composition. The atomized powder compositions disclosed in the methods herein are, in some embodiments, Sc x Al 1-xThis includes the range where x is in the range of 0.05 to 0.5, for example, x is in the range of 0.05 to 0.50, 0.10 to 0.50, 0.08 to 0.45, 0.15 to 0.45, 0.25 to 0.45, 0.20 to 0.40, 0.05 to 0.10, 0.10 to 0.15, 0.15 to 0.20, 0.20 to 0.25, 0.25 to 0.30, 0.30 to 0.35, 0.35 to 0.40, 0.40 to 0.45, or 0.45 to 0.50. In certain embodiments, with respect to the lower limit, the Al-Sc sputtering target may include x = at least 0.05, e.g., at least 0.08, at least 0.10, at least 0.15, at least 0.20, at least 0.25, at least 0.30, at least 0.35, at least 0.40, or at least 0.45. With respect to the upper limit, the Al-Sc sputtering target may include x = up to 0.5, e.g., up to 0.50, up to 0.45, up to 0.40, up to 0.35, up to 0.30, up to 0.25, up to 0.20, up to 0.15, or up to 0.10. In some embodiments, x is equal to 0.30; or x is equal to 0.35; or x is equal to 0.38; or x is equal to 0.42.

[0051]

[0079] The atomized powder compositions disclosed by the methods of this specification include, in some embodiments, 5 to 50 atomic percent scandium, for example, 10 to 50 atomic percent, 5 to 45 atomic percent, 8 to 45 atomic percent, 15 to 45 atomic percent, 25 to 45 atomic percent, 20 to 40 atomic percent, 5 to 10 atomic percent, 10 to 15 atomic percent, 15 to 20 atomic percent, 20 to 25 atomic percent, 25 to 30 atomic percent, 30 to 35 atomic percent, 35 to 40 atomic percent, 40 to 45 atomic percent, or 45 to 50 atomic percent scandium. Regarding the lower limit, the powder may contain at least 5 atomic percent of scandium, for example, at least 8 atomic percent, at least 10 atomic percent, at least 15 atomic percent, at least 20 atomic percent, at least 25 atomic percent, at least 30 atomic percent, at least 35 atomic percent, at least 40 atomic percent, or at least 45 atomic percent of scandium. Regarding the upper limit, the powder may contain up to 50 wt% of scandium, for example, up to 45 wt%, up to 40 wt%, up to 35 wt%, up to 30 wt%, up to 25 wt%, up to 20 wt%, up to 15 wt%, or up to 10 wt% of scandium. The powder composition may be the same as any of the target compositions detailed above.

[0052]

[0080] Powder particle size. Atomized Al-Sc powder can have its particle size reduced by grinding and / or milling. The atomized Al-Sc powder disclosed herein may have particle sizes ranging from 2 microns to 300 microns. The powder particles are not single crystals but particle aggregates consisting of numerous crystal grains.

[0053]

[0081] In some embodiments, the atomized Al-Sc powder is characterized by having an average particle size in the range of 2 to 300 microns, for example, 10 to 250 microns, 10 to 150 microns, 50 to 225 microns, or 100 to 200 microns. In some embodiments, the atomized Al-Sc powder disclosed herein may have a particle size in the range of 100 to 200 microns.

[0054]

[0082] With respect to the lower limit, the atomized Al-Sc powder may be characterized by having an average particle diameter of at least 2 microns, for example, at least 10 microns, at least 50 microns, or at least 100 microns. With respect to the upper limit, the powder may be characterized by having an average particle diameter of up to 300 microns, for example, up to 250 microns, up to 225 microns, up to 200 microns, or up to 150 microns.

[0055]

[0083] Powder particle size distribution. Atomized powder has a narrow particle size distribution. This is thought to result in a uniform phase distribution in the sputtering target to which it is subsequently solidified. The atomized Al-Sc powder disclosed herein has a particle size distribution D in the range of 50 microns to 150 microns. 50 It may have a particle size distribution D in the range of 50 microns to 150 microns, for example, 60 microns to 140 microns, 80 microns to 120 microns, or 90 microns to 100 microns. 50 It is characterized by having a particle size distribution D in the range of 90 microns to 100 microns. In one embodiment, the atomized Al-Sc powder disclosed herein has a particle size distribution D in the range of 90 microns to 100 microns. 50 It may have.

[0056]

[0084] Powder shape and internal pores. The atomized Al-Sc powder disclosed herein may contain spherical particles. Spherical particles exhibit good fluidity. In some embodiments, the spherical particles of the atomized powder useful in the methods herein include porosity and internal (or central) pores.

[0057]

[0085] Impurity content. In some cases, Al-Sc sputtering targets are highly pure and contain as few contaminants as possible. For example, oxygen can be extremely detrimental to the properties of piezoelectric films, causing both preferential bonding to the matrix and stabilization of phases other than the piezoelectric phase. Therefore, atomized Al-Sc powders disclosed by the methods herein should contain as little oxygen as possible. Oxygen is a function of scandium content, with higher scandium content resulting in higher oxygen content. For Al-30%Sc powder, in some embodiments, the powder contains up to 2000 ppm of oxygen, e.g., up to 1750 ppm, up to 1500 ppm, up to 1250 ppm, up to 1000 ppm, up to 600 ppm, or up to 300 ppm.

[0058]

[0086] The presence of transition metal elements such as iron should also be kept to a minimum. Therefore, the atomized Al-Sc powder disclosed by the method herein should contain as few metallic impurities as possible. In some embodiments, the powder contains up to 2000 ppm of metallic impurities, for example, up to 1750 ppm, up to 1500 ppm, up to 1250 ppm, up to 1000 ppm, up to 750 ppm, or up to 500 ppm.

[0059]

[0087] In some embodiments, the atomized powder contains up to 1000 ppm, or up to 600 ppm, or up to 300 ppm of oxygen. In some embodiments, the atomized powder contains up to 500 ppm of transition metal elements. During the solidification process, the oxygen content may increase. In some embodiments, the aluminum-scandium alloy sputtering target contains up to 2000 ppm, up to 1000 ppm, up to 600 ppm, or up to 300 ppm of oxygen.

[0060] Target phase.

[0061]

[0088] After solidification, the Al-Sc sputtering target has a composition containing 5 to 50 atomic percent scandium and 50 to 95 percent aluminum (including other elements as needed), as described above. The composition of the sputtering target matches the composition of the atomized powder used for solidification. The sputtering targets disclosed herein may contain free aluminum (Al), Al3Sc, Al2Sc, AlSc, combinations thereof, and possibly trace amounts of other phases. The sputtering targets disclosed herein may not contain Al2O3, or may substantially not contain it.

[0062]

[0089] In certain embodiments, the Al-Sc sputtering target has a composition of Sc x Al 1-x (x=0.05) is present. For example, the phase present in a target containing 5 atomic percent scandium (the remainder being aluminum) contains (mainly) free aluminum (Al) and the intermetallic phase Al3Sc.

[0063]

[0090] In other specific embodiments, the Al-Sc sputtering target is composed of Sc x Al 1-x (x=0.3) is present. For example, the phase present in a target containing 30 atomic% scandium (the remainder being aluminum) includes (mainly) the intermetallic phases Al3Sc and Al2Sc. In a preferred embodiment, an Al-Sc sputtering target contains at least 50% Al3Sc on an intensity basis determined by X-ray diffraction. Thus, when x=0.3, Al3Sc is the dominant phase in the target.

[0064]

[0091] The Al3Sc(L12) phase is preferred over the Al2Sc(Laves) phase, partly because of its characteristic equiaxed structure, rather than the dendritic structure of Al2Sc (which is prone to brittleness and cracking).

[0065]

[0092] In yet another embodiment, the Al-Sc sputtering target is composed of Sc x Al 1-xIt has (x=0.5). For example, the phase present in a target containing 50 atomic% scandium (the remainder being aluminum) contains (mainly) AlSc.

[0066] Target characteristics (Al-30%Sc)

[0093] Density. The Al-Sc sputtering targets of the methods disclosed herein are dense sintered targets. The density depends on the target composition. In embodiments having Al-30%Sc, the density of the targets disclosed herein is at least 2.9 g / cm³. 3 The theoretical density is 3.03 g / cm³. 3 In some embodiments, the target density is at least 2.9 g / cm³. 3 For example, at least 2.95 g / cm³ 3 at least 2.98 g / cm³ 3 at least 2.99 g / cm³ 3 at least 3.00 g / cm³ 3 , or at least 3.03 g / cm³ 3 In some embodiments, the target density is at least 97% of the theoretical density, for example, at least 98%, at least 99%, at least 99.5%, at least 99.9%, or at least 100% of the theoretical density.

[0067]

[0094] Impurity content. As mentioned above, Al-Sc sputtering targets are of high purity and contain as few contaminants as possible. Therefore, targets disclosed in the methods herein should contain as little oxygen as possible. In some embodiments, the target contains up to 2000 ppm of oxygen, for example, up to 1750 ppm, up to 1500 ppm, up to 1250 ppm, or up to 1000 ppm.

[0068]

[0095] The presence of transition metal elements such as iron should also be minimized. Therefore, the targets disclosed by the methods herein should contain as few metal elements as possible. In some embodiments, the powder contains up to 2000 ppm of metal elements, for example, up to 1750 ppm, up to 1500 ppm, up to 1250 ppm, up to 1000 ppm, up to 750 ppm, or up to 500 ppm.

[0069]

[0096] In one embodiment, the target contains up to 1000 ppm of oxygen. In another embodiment, the target contains up to 500 ppm of a transition metal element.

[0097] Hardness. The Al-Sc sputtering targets of the methods disclosed herein are hard. Hardness also depends on the target composition. Targets with low x (low Sc content) will have lower hardness due to the high Al content (ductile phase). In some embodiments, the targets of this specification exhibit a hardness of at least 340 HV. Targets of the methods described herein exhibit hardness values ​​of 340 HV to 400 HV, for example, 345 HV to 390 HV, or 350 HV to 380 HV, in some embodiments. With respect to the lower limit, targets may exhibit a hardness of at least 340 HV, for example, at least 345 HV, or at least 350 HV. With respect to the upper limit, targets may exhibit hardness values ​​of up to 400 HV, for example, up to 390 HV, or up to 380 HV.

[0070]

[0098] Dimensions. The Al-Sc sputtering target of the method disclosed herein may be large, for example, having a diameter of at least 50 mm, at least 100 mm, at least 200 mm, at least 300 mm, at least 400 mm, or at least 450 mm. The thickness of the target herein may be at least 5 mm, at least 8 mm, or at least 10 mm. In certain embodiments, the target of the method herein has a diameter of at least 100 mm and a thickness of at least 8 mm.

[0071]

[0099] In the examples herein, “as-cast” or “casting” refers to comparative examples manufactured by conventional methods. Powder metallurgy (PM), gas atomization (GA), hot pressing (HP), and discharge plasma sintering (SPS) refer to the examples of the present invention herein.

[0072]

[0100] In some embodiments, any or some of the components disclosed herein may be considered optional. In some cases, the disclosed compositions may expressly exclude any or some of the aforementioned components or process steps described herein, for example, by the language of the claims. For example, the language of the claims may be modified to state that the disclosed compositions do not utilize or contain one or more of the aforementioned impurities or phases. For example, the language of the claims may be modified to state that the disclosed targets do not contain the Al2Sc phase. Such negative limitations are anticipated, and this specification serves as the basis for any negative limitations with respect to components, steps, and / or features.

[0073]

[0101] In this specification, the limitations “at least” and “at most” may include the numerical values ​​associated therewith. In other words, “at least” and “at most” may be interpreted as “at least or equal to” and “at most or equal to.” This wording may subsequently be amended in the claims to include “or equal to.” For example, “at least 1.0 mm” may be interpreted as “at least 1.0 mm or equal to 1.0 mm” and subsequently amended in the claims. [Examples]

[0074] Materials and Procedure

[0102] Three types of pre-alloy powders with nominal compositions of 5 atomic%, 30 atomic%, and 50 atomic% Sc-Al were produced by centrifugal helium atomization (GA). A schematic diagram of the system is shown in Figure 2. As starting materials, distilled Sc strips (purity 3N) and Al rods (purity 5N) were induced by vacuum melting using a "gradient injection method" with two refractories. Crucible contamination was mainly due to Mg and Si, which were controlled to a maximum of 400 ppm. The final total amount of metal impurities in the GA powder was a maximum of 800 ppm. Oxygen control in the powder manufacturing process is also an important consideration. Table 1 shows the oxygen levels at each stage of production for the three Sc-composition GA powders.

[0075]

[0103]

[0076] [Table 1]

[0104] Table 1 shows that oxygen levels increased with Sc content and then leveled off after prolonged exposure to air. Oxidation stopped when the powder surface was completely covered with oxide. EDS analysis indicated that the oxide was primarily Sc2O3, not Al2O3. The 5%Sc-Al GA powder had a remarkably low oxygen content, likely due to its significantly lower melting point and lower reactivity compared to high-Sc alloys, resulting in minimal crucible reaction during melting and minimal oxidation throughout the process.

[0077]

[0105] Atomized powders may be ground and / or milled to reduce particle size. For example, after atomization, the recovered powders were sieved to 100 mesh (5%Sc and 30%Sc) and -200 mesh (50%Sc), respectively. One reason why the 50%Sc powder has a higher oxygen level when exposed to air is that its particle size is smaller (-200 mesh) compared to the -100 mesh of the 5%Sc and 30%Sc. Smaller particle sizes lead to higher heat exchange efficiency (sintering effect) and finer structures, but the resulting increase in oxygen is a concern. Considering the trade-off between the two, a particle size of -100 mesh (approximately 150 microns) is recommended.

[0078]

[0106] Figure 3 shows the particle size distribution (PSD) of GA 30% measured by laser scattering. The PSD is narrow, with D50 = 90-100 microns. Because the particles are spherical, good fluidity can be expected.

[0079]

[0107] GA powder was sintered by inert gas hot pressing (IGHP) and discharge plasma sintering (SPS). The powder was handled in an Ar-filled glove box, and moisture and oxygen were controlled to a maximum of 5 ppm. HP was performed in-house under an argon atmosphere using a BN-coated graphite tool set, with the powder covered on both sides with graphite foil. SPS was operated with pulsed DC current. Test specimens were processed with the graphite tool set. The thermal cycle involved raising the powder to a set temperature of 1000-1100°C at a heating rate of 10,000-15,000 A, with a current of 5,000-7,500 A / min, under a vacuum / Ar / H2 atmosphere and an initial pressure of 6-15 MPa. The sample was then held isothermally for 10 minutes, after which the pressure was increased to 45-65 MPa. The resulting product was a disc puck with a diameter of 100 mm and a thickness of 8 mm.

[0080]

[0108] The pressed pack was machined and polished into a target with a diameter of 75 mm x 6 mm. Using this target, Ar pressure 3 x 10 -3 Film deposition was performed by magnetron sputtering under conditions of mbar and a flow rate of 200 sccm. Before deposition, the process chamber was 1 × 10 -6 The exhaust was reduced to mbar. The power density was 10 W / cm². 2 The voltage was kept constant. The sputtering power was increased to 440W over 3 minutes. The target was first sputtered for 3 minutes (test run 1 for arcing and particle generation), then released into the atmosphere, evacuated, operated for 12 hours (test run 2), and finally restarted for 3 minutes without vacuum breaking (test run 3).

[0081] Gas atomizing (GA) powder

[0109] Nearly spherical powder particles are typically produced by atomization using various inert gases (mainly argon or helium). The inert gas environment prevents oxidation and promotes convective cooling. Figure 4 shows SEM micrographs of three types of gas-atomized Al-Sc powders. The 5% (Figure 4a) and 50% (Figure 4c) powders are mainly spherical with some satellite particles. The GA 30% powder is partially non-spherical with minimal satellite formation, although some fragmented particles are present (Figure 4b). Both of these may be evidence of lower superheating due to the higher liquidus temperature when the same injection temperature (1410°C) is used for both the 30% and Sc 50% compositions. Non-spherical droplets were formed by solidification, and then became spherical.

[0082]

[0110] As shown in Figure 4d, the particle surface of GA5% is not smooth but exhibits a tortoise-shell-like structure, which is evidence of the formation of equiaxed microstructures during the solidification process. In Figure 4e, faint fine artifacts are observed in GA30%, which are thought to be Al2Sc dendrites, as will be discussed later. In Figure 4f, satellite formation can be observed in GA50%.

[0083]

[0111] Cross-sectional images can reveal artifacts that indicate potential manufacturing conditions or processing problems. Figure 5 shows cross-sectional views of the atomized powder. The 5% (Figure 5a) and 30% GA powders (Figure 5b) show many pores in the center, while the 50% powder (Figure 5c) has the fewest pores. In the 30% powder, many cracks and voids are already present at the edges of the particles, consistent with the surface morphology shown in Figure 4b.

[0084]

[0112] Internal pores are commonly observed in GA powder particles. During the powder formation process, the liquid metal interacts with an inert gas environment, trapping a considerable amount of gas within the particles. The low pore size of 50% powder is thought to be due to two factors: 1) small particle size, and 2) close to a eutectic composition. Regarding the latter, because eutectic formation has a narrow solidification temperature range, solidification shrinkage between dendrites becomes finer, resulting in finer voids. Large pores containing gas are unsuitable for solidification because they are difficult to remove by diffusion.

[0085]

[0113] Backscattered electron images reveal compositional differences. BSE micrographs of the 5% (Figure 5d) and 30% (Figure 5e) samples show a two-phase structure. EDS analysis revealed that the 5% sample contained an Al (matrix) + Al3Sc (white) phase, while the 30% sample consisted of an Al2Sc (white dendrite) + Al3Sc (matrix) phase. The Al3Sc phase, the dominant phase of the 5% sample, exhibited a fine cellular structure (1-2 microns) due to rapid solidification, with occasional larger cells (10 microns). This equiaxed cellular structure is consistent with the surface morphology shown in Figure 4d and is thought to be related to the broad solidification temperature range ΔT shown in the Al-Sc phase diagram in Figure 6. The Al2Sc phase that precipitated first in the 30% sample (Figure 5e) mainly exhibited a dendritic structure, which is thought to be the result of a combination of cooling rate, temperature gradient, and solidification temperature range. Two ultrafine radial dendrite clusters were also observed in the 30% atomized particles (Figure 5e), which may have originated from two surface nucleation sites. One explanation for the observed microstructure is that molten droplets collided with small solidified particles, forming solidification nuclei at their edges, resulting in the growth of radial dendrites outward from these nucleation sites. This is a typical example of heterogeneous nucleation.

[0086]

[0114] The cross-sections of the 50% particles (Figure 5c, f) show no phase structure artifacts in either the BSE or SED images, suggesting the possibility of a single phase structure with no compositional differences.

[0087]

[0115] Figure 7 shows detailed observation results of the dendrites and internal structure within the central pores of GA30% particles. A network-like skeletal structure was observed inside the central pores, clearly indicating the formation of primary Al2Sc (confirmed by EDS) before the peritectic reaction occurred. The closed pores inhibited further penetration of the liquid phase into the Al2Sc dendrites, preventing the formation of the Al3Sc phase.

[0088]

[0116] The dendritic structure is associated with segregation. In GA 30% powder, dendrites (Al2Sc) have a higher melting point compared to the interdendritic regions of the matrix. Particle size and secondary dendrite arm spacing (DAS) are commonly used to evaluate segregation / homogenization. Fine DAS and particle size of GA powder are obtained by rapid cooling and fine particle size. From the inset in Figure 7, the DAS was measured at 1-2 microns, and the solidification time t E This determines the spacing between the dendrite arms. Generally, the following principle (Equation 3-1) applies.

[0089]

number

[0090]

[0117] Table 2 summarizes the particle size, density, and flow properties of three different compositional powders. It is clear that the low density of the 5% powder is mainly due to its composition. The densities of both the Sc and Al-Sc intermetallic phases are 3 × 10⁻⁶. 3 kg / m 3 While it is almost equivalent to that, aluminum is 2.7 × 10 3 kg / m 3It is lightweight. The Hausner ratio of the 5% powder is similar to the others because the density differences between phases cancel each other out. Comparing the 30% and 50% powders, although the apparent densities are similar because the densities of all intermetallic compounds are close, the 50% powder has a higher tap density and therefore a higher Hausner ratio. A higher Hausner ratio indicates a greater increase in particle density due to vibration. The GA 50% powder has a small particle size and high interparticle friction, so it does not pass through the Hall flow meter, which is undesirable in most additive manufacturing. A higher tap density may improve compressibility, but the main reason for this is pressure. From a sintering perspective, -200 mesh fine particles may be superior to -100 mesh coarse particles, but -100 mesh was selected in the 30% powder solidification test considering oxygen control.

[0091]

[0118]

[0092] [Table 2]

[0119] Figure 8 shows the X-ray diffraction patterns of three types of GA powder. As shown in the figure, GA Sc5% and Sc30% consist of two phases, a pure Al+L12 phase and an L12+C15 phase, respectively, while GA 50% shows only a single B2 phase. To our knowledge, XRD indexing data for Al-Sc systems has not been published, and in particular, B2 structure data is not included in the ICDD reference database. Therefore, as shown in Figure 8, we attempted to index all Miller index (hkl) peaks appearing in the 2θ range of 20-75°.

[0093]

[0120] The lattice parameter constants for each peak shown were calculated using equation (2-3). Table 3 summarizes the calculation results of diffraction indices and lattice parameters for all three related intermetallic phases. The calculated lattice parameters (Al3Sc: 0.3996 nm, Al2Sc: 0.7393 nm, AlSc: 0.3310 nm) are consistent with the ASM phase diagram data (0.4101 nm, 0.7600 nm, 0.3388 nm). The agreement of the lattice parameter calculation results for Al2Sc supports the fact that it is a cubic C15 Laves phase, not a tetragonal C14 structure. This agreement further suggests that AlSc is a cubic B2 structure, not a tetragonal phase. Furthermore, the small variation when using different peaks for each phase suggests that the indexing is quite accurate.

[0094]

[0121]

[0095] [Table 3]

[0122] The superlattice peaks of L12(Al3Sc) are (100), (110), (210), and (211), while the fundamental peaks (111), (200), and (220) overlap with the peaks of the Al phase in GA Sc 5% powder, as shown in Figure 8. Al has an fcc structure, while L12 has an ordered fcc structure, and the overlapping peaks indicate that the lattice parameters of both phases are close. The mismatch between the lattice parameters of Al and Al3Sc is calculated to be 1.37% at room temperature, assuming the lattice parameter values ​​of Al and Al3Sc are 0.3942 nm and 0.3996 nm, respectively, without considering residual stress. This small mismatch forms the basis of precipitation-strengthened Sc-added aluminum alloys, and the precipitated nano-sized L12-Al3Sc particles adhere closely to the Al matrix due to the small mismatch. The Al3Sc / Al interface has high strength, which causes pinning of dislocations and grain boundaries, and can significantly refine the grain size of castings.

[0096] Consolidation

[0123] Examples 1 and 2: AlSc 5% (x=0.05) and AlSc 50% (x=0.5)

[0124] GA Sc 5% powder was sintered in an IGHP at 600°C and 30 MPa to obtain a perfectly dense (2.77 g / c) target. Figure 9 shows the typical microstructure of Example 1, a pressed sample, on the right. For comparison, Comparative Example 1 (CE1), a cast sample, is shown on the left. In the hot-pressed Example 1, a brighter Al3Sc phase is uniformly distributed within the Al matrix. Example 1 shows a fine microstructure with an average Al3Sc particle size of approximately 1-3 microns. Comparative Example 1 shows that the average Al3Sc particle size in the casting is considerably larger, at approximately 50 microns (for example, at least 10 times larger than that of Example 1).

[0097]

[0125] A perfectly dense target (3.07 g / cc) was obtained from GA Sc 50% powder by IGHP at 1100°C and 30 MPa. Figure 10 shows the typical microstructure of Example 2 (left) and the corresponding EDS elemental mapping (Sc, Al) (right). As shown in the figure, the microstructure of Example 2 is mainly single-phase B2 AlSc, with almost no internal pores (appearing black). The elemental mapping (right) shows that the distribution of Al and Sc within Example 2 is very uniform.

[0098]

[0126] Example 3: AlSc 30% (x=0.3)

[0127] Figure 11 shows the DTA plot for GA Sc 30%. The thermogram during heating shows neither exothermic nor endothermic peaks, indicating that no phase transition occurs below 1250°C. The broad, bell-shaped peak in the heating curve was likely related to the stress relaxation process (due to rapid cooling during atomization). No free Al phase was present in the GA 30% powder. Interestingly, an endothermic peak was observed in the cooling curve at 658°C, corresponding to Al precipitation. Since the peritectic temperature is considerably higher than 1250°C (1316°C according to the phase diagram), Al precipitation at this temperature was unexpected. One possible explanation is that initial melting occurred, leading to the peritectic reaction (L + Al2Sc ⇔ Al3Sc). Based on the DTA analysis, pressing at temperatures below 1250°C is desirable.

[0099]

[0128] Sputtered targets were manufactured using the inert gas hot pressing (IGHP) method and the discharge plasma sintering (SPS) method. The process parameters and obtained properties are summarized in Table 4. Examples 3.1 to 3.4 were manufactured using the hot pressing method, and Examples 3.5 to 3.8 were manufactured using the discharge plasma sintering method. The results for a comparative target, Comparative Example 2 (CE2), manufactured using a conventional molten casting method, are also included in the table. It can be seen that the optimal temperature and pressure for obtaining a perfectly dense target are similar for the IGHP targets (Examples 3.1 to 3.4) and the SPS targets (Examples 3.5 to 3.8). However, the soak time and cycle time for the latter were significantly reduced. Compared to the casting (CE2), Examples 3.1 to 3.8 showed significantly higher electrical conductivity. This is thought to be due to fewer pores and a finer microstructure. Furthermore, the examples of the present invention showed higher hardness, which is also thought to be due to the acquisition of a uniform and finer microstructure.

[0100]

[0129] In all press targets, the total amount of metal impurities was confirmed to be a maximum of 1000 ppm, and the oxygen content was a maximum of 2000 ppm. Low oxygen incorporation was observed in both the HP and SPS methods. The 30% Sc powder immediately after atomization was low in oxygen (<300 ppm), but subsequently increased to at least 1500 ppm before solidification in the recovery process not protected by an inert atmosphere (see Table 1). Under controlled conditions, the final oxygen content is considered controllable to a maximum of 1000 ppm (similar to the level of cast targets). Table 5 shows typical impurity analysis values ​​for Example 3.2, which was hot-pressed, with a total metal impurity content of 793 ppm and oxygen content of 1786 ppm.

[0101]

[0130]

[0102] [Table 4]

[0131]

[0103] [Table 5]

[0104]

[0132] Examples 3.1-3.4 IGHP AlSc 30% (x=0.3)

[0133] Figure 12 is an optical microscope image showing the microstructure of all four hot-pressed examples 3.1 to 3.4, which have an Al2Sc phase (darker phase) and an Al3Sc phase (brighter matrix phase). In the examples pressed at 1000°C (Example 3.4) and 1100°C (Examples 3.1 and 3.3), the amount of the Al2Sc phase remained constant, and no significant coarsening was observed compared to the starting powder (see Figures 5 and 7). However, when the temperature was increased to 1250°C (Example 3.2), the Al2Sc phase region grew significantly from 1-3 microns to 5-10 microns, as shown in Figure 12 (HP2, Example 3.2). The pressurizing pressure also had an effect. At a low pressure of 15 MPa, the majority of grain boundary pores were not closed (Example 3.1), resulting in a decrease in density (95.9%), but at the same temperature of 1100°C and a high pressure of 45 MPa (Example 3.3), a perfectly dense target was obtained. In the temperature and pressure ranges shown in Table 4, porosity (for example, shown in black in Example 3.4) remained in all hot pressing examples using IGHP (Examples 3.1 to 3.4).

[0105]

[0134] Thermal analysis (Figure 8) showed that Al precipitated during cooling after heating to 1250°C, but no free Al phase was detected even in hot pressing at the maximum temperature of 1250°C (Example 3.2). Since hot pressing is a slow cooling process, it is thought that the small amount of precipitated Al reacted with Al2Sc to form Al3Sc. To confirm this, Example 3.1 was further heat-treated at 1200°C for 2 hours (Example 3.1.1) and then water-cooled. As shown in Figure 13, Al precipitated, but mainly occurred at the edges of the sample. At these edges, Sc was locally lost due to surface oxidation, promoting Al precipitation. On the other hand, the Al2Sc phase around the Al phase region had transformed into Al3Sc. This is shown in the optical microscope image (left) of Figure 13 and was also confirmed in the EDS image (right). In the EDS image, Al3Sc was detected at positions 001 and 003, Al2Sc at position 002, and Al at position 002. Furthermore, in the surrounding pore and grain boundary regions where the defect free energy is high, most of the darker Al2Sc phase has transitioned to the brighter Al3Sc (see Figure 12, HP1, 3, and 4, corresponding to Examples 3.1, 3.3, and 3.4, respectively).

[0106]

[0135] The change in the Al3Sc / Al2Sc phase ratio at different process stages is supported by the changes in peak density shown in the XRD plots for the gas atomized powder (Figure 14a), the casting comparative example (CE2) (Figure 14b), hot press example 3.1 (Figure 14c), and heat-treated hot press example 3.1.1 (Figure 14d) shown in Figure 14. Figure 14b shows that while the dominant phase in the casting comparative example was Al2Sc(C15), the dominant phase present in the GA powder and HP samples of the present invention (Figures 14a and 14c) was Al3Sc(L12). This was observed from the changes in peak intensity of the L12(111) and C15(311) phases. This is an important and unexpected finding that the dominant phase is Al3Sc when the scandium content is x=0.30 (or higher), as in Example 3. With this high scandium content, the dominant phase should have been Al2Sc, as confirmed in the comparative example (according to the phase diagram in Figure 6). The unexpectedly high Al3Sc content in the examples of the present invention provides higher fracture toughness, thereby conferring high resistance to cracking and ensuring the long life of targets prepared according to the method herein. Hereinafter, the dominant phase refers to the phase that is most abundant in terms of strength. Furthermore, a small Sc2O3 peak was observed in the heat-treated sample, as shown in Figure 14d. This is consistent with the results of microstructural studies (the dark gray phase in Figure 13 (left) is scandium oxide). No free Al was detected by X-ray diffraction. This indicates that, even if aluminum metal is present, it would only be up to 3% by weight, given the detection limits of this method.

[0107]

[0136] Phase ratio analysis was performed by measuring the integrated intensity and peak height of the strongest peaks obtained from both the L12(111) phase and the C15(311) phase. Table 6 summarizes the changes in phase intensity ratios under different conditions for the casting (comparative example) and the HP sample. The atomized powder had a considerably higher amount of Al3Sc(L12) compared to the casting. The phase ratio did not change with HP at 1100°C, but the amount of Al3Sc phase increased slightly further with heat treatment at 1200°C (Example 3.1.2), which is consistent with previous results (Figure 13).

[0108]

[0137] According to the lever principle, the Al3Sc and Al2Sc phases in the equilibrium phase diagram are 39.8 atomic% and 60.2 atomic% respectively. Atomization is a rapid cooling process, resulting in less primary Al2Sc formation. Subsequently, more liquid phase undergoes peritectic reactions with the Al2Sc phase, forming more Al3Sc phase, thus increasing the Al3Sc / (Al3Sc+Al2Sc) ratio.

[0109]

[0138]

[0110] [Table 6]

[0111]

[0139] Examples 3.5-3.8: SPS AlSc 30% (x=0.3)

[0140] Figure 15 shows the discharge plasma sintering process control. The starting pressure was 15 MPa, and densification was promoted by pre-compression. The final temperature was 1100°C, and the holding time was 22 minutes. The cooling rate was 15.9°C / min. The total cycle time was a maximum of 2 hours. Notably, the processing time for the discharge plasma sintering method was a maximum of 2 hours, which is significantly shorter than the conventional hot press method, which typically takes 12 to 24 hours. SPS also used a shorter processing time compared to IGHP described in Examples 3.1 to 3.4 above.

[0112]

[0141] Figure 16 shows the microstructures of Examples 3.5 to 3.8 mentioned in Table 4, with Example 3.5 in the upper left, Example 3.6 in the upper right, Example 3.7 in the lower left, and Example 3.8 in the lower right. Surprisingly, the sintering temperature (1000°C vs. 1100°C) and time (10 to 40 minutes) did not significantly affect the size of the phase region and the final density (see Table 4). Increasing the press pressure from 45 MPa to 55 MPa and then to 65 MPa did not significantly affect the properties. However, it was confirmed that using SPS allows for lower temperatures and shorter times (compared to hot pressing) while maintaining a fine microstructure. Example 3.8, sintered at 1000°C, had the same density as the targets of Examples 3.5 to 3.7, which were sintered at a higher temperature of 1100°C, but grain boundary pores were observed. The oxide particles shown as black dots in Figure 16 are submicron (e.g., maximum 0.2 μm) and are mainly dispersed at the grain boundaries.

[0113]

[0142] Figure 17 shows the uniform microstructure and phase morphology of Example 3.5. Figure 17 shows that Example 3.5 exhibits a darker Al2Sc phase and a brighter Al3Sc phase, indicating a fine microstructure due to a uniform phase distribution.

[0114]

[0143] For comparison, a conventional casting target CE2 is shown in Figure 18. In the CE2 casting target example, a wide area of ​​the darker Al2Sc phase (e.g., at least 200 microns) and a wide area of ​​the brighter Al3Sc phase (e.g., at least 200 microns) are observed.

[0115]

[0144] Figures 19 and 20 show the grain morphology of Example 3.5 and CE2, respectively, using electron backscatter diffraction (EBSD) images. Figure 19 shows that the target of SPS Example 3.5 had an average grain size of approximately 3.8 microns, calculated by image analysis (equivalent circle diameter, area-weighted average). Figure 20 shows that the average grain size of the cast CE2 target was approximately 200-300 microns.

[0116]

[0145] The microhardness data for Example 3.5 is shown in Table 7.

[0146]

[0117] [Table 7]

[0147] Since Vickers hardness is sensitive to load, the variation (standard deviation) decreased with increasing load. This is attributable to increasing the indenter size to cover a wider area of ​​at least partially different phases (Al3Sc and Al2Sc). At each load, measurements were taken at five locations on the target surface: four locations spaced along the target diameter (two near the outer circumference at both ends of the diameter), and the fifth location near the outer circumference perpendicular to the diameter. The hardness at these locations was found to be very uniform. For example, the hardness values ​​for HV2 (load 2kg) in Example 3.5 were 316.8, 308.5, 304.6, 311.2, and 313.1, with a standard deviation of 4.1. This uniform hardness also suggests a uniform distribution and fine microstructure of the phases in Example 3.5. Conventional targets commonly develop cracks (or break) during operation (due to thermal shock or bending caused by water pressure used to cool the backing plate), whereas the targets described herein have the aforementioned microstructural advantages and reduce cracking. This is because the more ductile AlSc30% targets have higher fracture strength and also offer the advantage of improved sputtering rate.

[0118]

[0148] In Example 3.5, scandium content was measured by X-ray fluorescence analysis (XRF) at five locations on the upper and lower surfaces of the target. As shown in Table 8, the chemical composition was uniform throughout the entire diameter and thickness. For comparison, the chemical composition of the casting is shown in International Publication No. 2018 / 169998A1, which is incorporated herein by reference.

[0119]

[0149]

[0120] [Table 8]

[0150] Electrical conductivity was measured for Example 3.5 according to ASTM E1004-17, and the data are shown in Table 9. The data show that the electrical conductivity is very uniform, suggesting a uniform distribution of scandium and low porosity.

[0121]

[0151]

[0122] [Table 9]

[0123] Destruction mechanism of PM 30%Sc

[0152] Polycrystalline L12 (Al3Sc) exhibits brittleness at room temperature despite its basic fcc structure. Fracture has been observed to occur primarily intragranularly, accompanied by cleavage along the {011} plane. The C15 Al2Sc Laves phase is typically very brittle at room temperature, further reducing toughness. 30%Sc consists of both the Laves phase and the L12 brittle phase and is known to crack easily during machining and grinding. In PM 30%Sc products, a lower Laves phase may improve crack resistance.

[0124]

[0153] Hardness measurements at room temperature have been used to evaluate the relative strength and ductility of materials. Figure 21 compares Vickers indentations of samples prepared using castings (for comparison, Figures 21a and 21b), HP (Figure 21c), and SPS (Figure 21d). In the cast samples, clear differences are observed in indentation size and crack patterns between Al3Sc (lighter phase) and Al2Sc (darker phase) (Figures 21a and 21b). Note the difference in scale bar lengths. The indentation size of the Al3Sc phase is larger than that of the Al2Sc phase, corresponding to hardnesses of 175 HV and 611 HV, respectively, confirming that Al2Sc is more brittle than Al3Sc. As shown in Figure 21b, cracks from Al2Sc originated from the four indentation angles and propagated outward (radially). As shown in Figure 21a, all cracks from Al3Sc were related to / connected to the Al2Sc phase, and no cracks were observed at any of the indentation angles. This also supports the idea that the Al2Sc Raves phase is more brittle than the Al3Sc L12 phase.

[0125]

[0154] As shown in Figures 21c and 21d, the indentation size and crack patterns in the HP and SPS (Figures 21c and 21d) examples are nearly identical. Neither example shows long cracks originating from the corners of the indentation. Instead, short cracks are observed not only at the corners but also on the sides of the indentation. The complete absence of long propagating cracks originating from the corners of the Vickers indentation indicates that the PM Sc30% product exhibited higher fracture toughness than the comparative casting. This is due to the fine and uniform microstructure obtained by the method described herein. Another factor is the low amount of Raves phase in the PM product (see Table 6). While cast samples exhibit multiple cracks from each corner and / or non-uniform crack lengths, pressed PM samples show no cracks at the corners, thus allowing for the measurement of fracture toughness K using the Vickers microhardness test. 1c It is impossible to measure it quantitatively.

[0126]

[0155] Figure 22 shows micrographs of the fracture surface morphology of SPS Example 3.8 after bending, and grain boundary cracks caused by thermal stress after water cooling. The fracture surface after bending appears glossy and smooth to the naked eye, exhibiting a faceted structure due to the differing orientations of the cleavage planes within the crystal grains. Figure 22b shows a typical brittle intragranular fracture observed at high magnification, with river lines visible on the intragranular facets, pointing in the direction of grain boundaries / crystal grain boundaries. The crack appears to originate around the grain joint in the center of the image (Figure 22b), which is due to stress concentration occurring in that area. As shown in Figures 22a and 22c, the crack propagates between grains, and the shape and size of the crystal grains along the fracture path can be easily observed.

[0127] Magnetron sputtering

[0156] Table 10 shows an overview of the sputtering data. The HP Example 3.3 and SPS Example 3.8 targets showed significantly better performance than the cast target CE2 after 12 hours of continuous sputtering (approximately 33% of the target life), with minimal microarc generation and zero hard arcs.

[0128]

[0157]

[0129] [Table 10]

[0158] The target after sputtering is key to a deeper understanding of this method. In magnetron sputtering, a so-called "racetrack" is created where the plasma (and sputter removal) of the target material is concentrated, as shown in Figure 23. Figure 23a shows a used CE2 (cast) target, Figure 23b shows a used SPS Example 3.8 target, and Figure 23c shows a used HP Example 3.3 target. Example 3.3 in Figure 23c appears smoother and more reflective than the cast CE2 target (Figure 23a), which is thought to be due to an inherently more uniform and finer microstructure. On the other hand, the surface of SPS Example 3.8 is relatively rougher than that of HP Example 3.3, which is thought to be due to the presence of interparticle pores, as mentioned above. Sputtered targets manufactured by discharge plasma sintering and inert gas hot pressing showed a smoother surface compared to cast sputtered targets. This indicates improved sputtering and reduced arcing in the sputtered targets.

[0130]

[0159] A wide range of interaction factors influence the magnetron deposition of thin films. These factors include gas composition, flow rate / pressure, deposition time, deposition rate, power, distance between substrate and target, substrate temperature, electron temperature, and target manufacturing process. Figure 24 shows optical microscope images of the track region (Figure 24a) and the off-track region (Figure 24b) of a used SPS Example 3.8 target where the plasma is concentrated by the magnetic field. Molten nodules were generated in the track region, but the nodular features were not as pronounced in the off-track region. The different surface morphologies are a direct result of local sputtering conditions.

[0131]

[0160] Figure 25 shows the surface morphology of three used targets. Figure 25a is CE2 (cast), Figure 25b is SPS Example 3.8, and Figure 25c is HP Example 3.3. The cast CE2 target (Figure 25a) showed a faceted structure with larger nodules. Al3Sc (lighter phase) and Al2Sc (darker phase) were smoothly connected and coexisted within the same nodule, which may suggest that the sputtering rates of both phases were similar. The targets from SPS Example 3.8 and HP Example 3.3 (Figures 25b and 25c) showed defective spherical regions and black spots (possibly oxides). The fine and uniform microstructure of the PM targets (e.g., the targets from SPS Example 3.8 and HP Example 3.3) was observed to reduce arcing.

[0132] Example 4: HP AlSc 35% (x=0.35)

[0161] In Example 4, a target with the composition Al-35%Sc was prepared. The ingot was crushed and ball-milled to obtain a -100 mesh powder. The powder was then hot-pressed at 1100°C and 45 MPa / Ar for 4 hours (using the same parameters as in Example 3.3) to produce a target with a diameter of 100 mm and a thickness of 8 mm.

[0133]

[0162] Comparative Example 3 (CE3) was a net-shape target with the composition Al-35%Sc, which was induced by vacuum melting and cast in a horizontal graphite mold.

[0163] Figures 26 and 27 are X-ray diffraction (XRD) plots for Example 4 and CE3, respectively. These plots show that Example 4 exhibits an isotropic structure. In contrast, the casting comparative example CE3 exhibits a strong (511) structure. The isotropic structure of Example 4 offers the advantage of providing a uniform sputtering rate and thin film uniformity when forming thin films using the target of the present invention.

[0134]

[0164] The microstructure of CE3 is shown in the optical microscope image in Figure 28, where the columnar structure of the cast 35%Sc comparison target can be confirmed. The presence of the columnar grain structure is due to the large temperature gradient during solidification, which leads to grain orientation, confirming that CE3 does not have an isotropic structure.

[0135]

[0165] In the following description, certain terms are used for clarity, but these terms refer only to specific structures of the embodiments illustrated in the drawings and do not define or limit the scope of this disclosure. In the drawings and the following description, identical numerical notations should be understood to indicate components of the same function.

[0136]

[0166] Unless the context clearly indicates a different meaning, the singular forms "a," "an," and "the" refer to multiple objects.

[0167] As used herein and in the claims, the term “contains” may include embodiments that “consume” and “essentially consist of.” The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s)” and their variations as used herein are intended as open-ended transitional phrases, terms, or words that require the presence of a specified component / component / step and permit the presence of other components / components / steps. However, such descriptions should also be interpreted as describing compositions, articles, or processes that “consume” and “essentially consist of” the enumerated components / components / steps, thereby permitting the presence of only the specified component / component / step and any impurities that may arise therefrom, and excluding other components / components / steps.

[0137]

[0168] The numerical values ​​in the specification and claims of this application should be understood to include numerical values ​​that are identical when converted to the same number of significant figures, and numerical values ​​that differ from the values ​​stated in this application within the experimental error of the conventional measurement techniques described herein in order to determine the values.

[0138]

[0169] All ranges disclosed herein include the stated endpoints and can be combined independently (for example, the range “2 grams to 10 grams” includes the endpoints of 2 grams or 10 grams, and all intermediate values).

[0139]

[0170] In this specification, the limitations “at least” and “at most” may include the associated numerical values. In other words, “at least” and “at most” may be interpreted as “at least or equal to” and “at most or equal to.” This wording may subsequently be amended in the claims to include “or equal to.” For example, “at least 4.0” may be interpreted as “at least 4.0 or equal to 4.0” and subsequently amended in the claims.

[0140]

[0171] When a material is described as having an average particle diameter or average particle diameter distribution, this is defined as the particle diameter at which 50% (by volume) of the total number of particles are achieved. In other words, 50% of the particles have a diameter larger than the average particle diameter, and 50% of the particles have a diameter smaller than the average particle diameter. The particle size distribution follows a Gaussian distribution, with the upper and lower quartiles being 25% and 75% of the specified average particle diameter, respectively, and all particles being up to 150% of the specified average particle diameter.

[0141]

[0172] The process steps described herein relate to temperature, and unless otherwise specified, refer to the temperature reached by the referenced material, not the set temperature of the heat source (e.g., furnace, oven). The term "room temperature" refers to the range of 20°C to 25°C (68°F to 77°F).

[0142]

[0173] The term "approximately" can be used to include any number that may vary without changing the fundamental function of its value. When used with a range, "approximately" also discloses a range defined by the absolute values ​​of the two endpoints; for example, "approximately 2 to approximately 4" also discloses the range "2 to 4". The term "approximately" may also refer to ±10% of the given number.

[0143] Embodiment

[0174] The following embodiments are conceivable. Any combination of features and embodiments is conceivable.

[0144]

[0175] Embodiment 1 Scx Al 1-x A method for producing an aluminum-scandium alloy sputtering target, comprising the steps of: atomizing to form a powder, wherein x is in the range of 0.05 to 0.5; and solidifying the powder to form a target having a microstructure characterized by an average particle size of up to 50 microns.

[0145]

[0176] Embodiment 2 Sc x Al 1-x A method for producing an aluminum-scandium alloy sputtering target, comprising the steps of: atomizing to form a powder, wherein x is in the range of 0.25 to 0.45; and solidifying the powder to form a target having a microstructure characterized by an average particle size of up to 50 microns, wherein the solidification includes heating under pressure to 900°C to 1200°C by at least one of discharge plasma sintering, ultra-high pressure sintering, hot pressing, inert gas hot pressing, and vacuum hot pressing.

[0146]

[0177] Embodiment 3: The method according to Embodiment 1, wherein x is in the range of 0.08 to 0.45.

[0178] Embodiment 4 The method according to any one of Embodiments 1 to 3, wherein the microstructure is characterized by an average particle size of up to 10 microns or up to 5 microns.

[0147]

[0179] Embodiment 5 The method according to any one of Embodiments 1 to 4, wherein the microstructure is characterized by two or more Al-Sc intermetallic phases distributed in phase regions with a diameter of up to 50 microns or a diameter of up to 10 microns.

[0148]

[0180] Embodiment 6 The method according to any one of Embodiments 1 to 5, wherein the target has an isotropic structure determined by X-ray diffraction. Embodiment 7 The method according to any one of Embodiments 1 to 6, wherein the atomizing comprises one or more of the following: atomizing comprising a powder having an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5; atomizing carried out by centrifugal helium atomization; atomizing to form a powder having up to 1000 ppm of oxygen, or up to 600 ppm of oxygen, or up to 300 ppm of oxygen; atomizing comprising further milling the powder to a particle size in the range of 100 microns to 200 microns; and atomizing comprising a powder having a particle size distribution D50 in the range of 90 microns to 100 microns.

[0149]

[0181] Embodiment 8: The method according to Embodiment 1 or Embodiment 2, wherein x is in the range of 0.25 to 0.33, and atomizing comprises a powder having an Al3Sc / (Al3Sc+Al2Sc) ratio of at least 0.5.

[0150]

[0182] Embodiment 9 The method according to any one of Embodiments 1 to 8, wherein the powder contains up to 1000 ppm of oxygen and up to 1000 ppm of metal impurities.

[0183] Embodiment 10 The method according to Embodiment 2, wherein the powder contains up to 300 ppm of oxygen.

[0151]

[0184] Embodiment 11 The method according to any one of Embodiments 1 to 10, wherein the target comprises one or more Al-Sc intermetallic phases; or the target comprises Al3Sc and Al2Sc; or the target comprises Al2Sc and AlSc; or the target is substantially free of Al2O3 and substantially free of free Al.

[0152]

[0185] Embodiment 12: The method according to any one of Embodiments 1 to 11, wherein x = 0.30; or x = 0.35; or x = 0.38; or x = 0.42.

[0186] Embodiment 13: An aluminum-scandium alloy sputtering target manufactured by the method described in any of Embodiments 1 to 12.

[0153]

[0187] Embodiment 14: An aluminum-scandium alloy sputtering target comprising one or more Al-Sc intermetallic phases containing Al-Sc intermetallic particles, wherein the average Al-Sc intermetallic particle size is up to 50 microns.

[0154]

[0188] Embodiment 15: An aluminum-scandium alloy sputtering target according to Embodiment 14, wherein the average Al-Sc intermetallic particle size is up to 10 microns.

[0155]

[0189] Although the present invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those skilled in the art. Given the preceding discussion, the relevant technical knowledge, and the references discussed above in relation to the background art and detailed description, all disclosures are incorporated herein by reference. Furthermore, it should be understood that the aspects of the invention described below and / or in the appended claims, some of the various embodiments, and various features described therein are, in whole or in part, interchangeable or interchangeable. In the preceding description of various embodiments, embodiments that refer to other embodiments can be appropriately combined with other embodiments as will be understood by those skilled in the art. Furthermore, those skilled in the art will understand that the preceding description is merely illustrative and not intended to be limiting.

Claims

1. A method for manufacturing an aluminum-scandium alloy sputtering target, Sc ｘ Al １－ｘ The steps include atomizing to form a powder, wherein x is in the range of 0.05 to 0.5; and The step of solidifying the powder to form a target having a microstructure characterized by an average particle size of up to 50 microns. Methods that include...

2. A method for manufacturing an aluminum-scandium alloy sputtering target, Sc ｘ Al １－ｘ The step of atomizing to form a powder, wherein x is in the range of 0.25 to 0.45; and The step of solidifying the powder to form a target having a microstructure characterized by an average particle size of up to 50 microns, wherein the solidification includes heating under pressure to 900°C to 1200°C by at least one of the following: discharge plasma sintering, ultra-high pressure sintering, hot pressing, inert gas hot pressing, and vacuum hot pressing. Methods that include...

3. The method according to claim 1, wherein x is in the range of 0.08 to 0.

45.

4. The method according to claim 1 or claim 2, wherein the microstructure is characterized by an average particle size of up to 10 microns or up to 5 microns.

5. The method according to claim 1 or claim 2, wherein the microstructure is characterized by two or more Al-Sc intermetallic phases distributed in phase regions with a maximum diameter of 50 microns or a maximum diameter of 10 microns.

6. The method according to claim 1 or claim 2, wherein the target has an isotropic structure determined by X-ray diffraction.

7. Atomizing, At least 0.5% Al ３ Sc / (Al ３ Sc+Al ２ Atomizing containing the powder having a Sc ratio; Atomizing performed by centrifugal helium atomization; Atomizing to form a powder having a maximum of 1000 ppm of oxygen, or a maximum of 600 ppm of oxygen, or a maximum of 300 ppm of oxygen; Atomizing, which includes further milling the powder to a particle size in the range of 100 microns to 200 microns; and Particle size distribution D in the range of 90 microns to 100 microns ５０ Atomizing comprising the powder having the above, The method according to claim 1 or claim 2, comprising one or more of the above.

8. x is in the range of 0.25 to 0.33, and atomizing is at least 0.5 Al ３ Sc / (Al ３ Sc + Al ２ Sc) ratio, the method according to claim 1 or claim 2, comprising said powder.

9. The method according to claim 1 or claim 2, wherein the powder contains up to 1000 ppm of oxygen and up to 1000 ppm of metal impurities.

10. The method according to claim 2, wherein the powder contains a maximum of 300 ppm of oxygen.

11. The target comprises one or more Al-Sc intermetallic phases; or the target is Al ３ Sc and Al ２ Including Sc; or the target is Al ２ Including Sc and AlSc; or the target is Al ２ O ３ The method according to claim 1 or claim 2, which substantially does not contain and substantially does not contain free Al.

12. The method according to claim 1 or claim 2, wherein x = 0.30; or x = 0.35; or x = 0.38; or x = 0.

42.

13. An aluminum-scandium alloy sputtering target manufactured by the method described in claim 1 or claim 2.

14. An aluminum-scandium alloy sputtering target containing one or more Al-Sc intermetallic phases, each containing Al-Sc intermetallic particles with an average Al-Sc intermetallic particle size of up to 50 microns.

15. The aluminum-scandium alloy sputtering target according to claim 14, wherein the average Al-Sc intermetallic particle size is a maximum of 10 microns.

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