Sputtering targets and processes for producing the same

Abstract

A process for producing an aluminum-scandium alloy sputtering target, the process comprising consolidating a first powder having at least 90 wt% or more of an aluminum powder that contains from 0 to 10 at% scandium and second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium. The sputtering target may comprise an alloy of aluminum and scandium and containing from 10 at% to 50 at% scandium.

Description

Sputtering Targets and Processes for Producing the SamePRIORITY CLAIM

[0001] This application claims priority to US Provisional Application No. 63 / 636,323, filed on April 19, 2024, the entire contents and disclosure of which is hereby incorporated by reference.FIELD

[0002] The present disclosure relates to sputtering targets and processes for producing the sputtering targets. In particular, the process uses powders in a consolidation process that produces a durable sputtering targeting suitable for forming a metal film or nitride film. In one embodiment, the durable sputtering targeting is less susceptible to cracking.BACKGROUND

[0003] Aluminum scandium nitride (AlxSci.xN) is of interest for the fabrication of 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 electro-acoustic applications. For example, AlScN films are used in the manufacture of the bulk acoustic wave (BAW) filters enabling 5G communications. A conventional method for manufacturing these piezoelectric thin films is by using reactive sputter deposition. The sputtering target, typically a metal or metallic alloy, is constructed of the material to be sputtered. The sputtering target and the substrate are placed in proximity to one another within the chamber and the target is bombarded with charged particles or ions. The high energy ions cause a portion of the sputtering target to dislodge and be re-deposited on the substrate. Sputtering is advantageous because it allows compositional control of the film, affords control of residual stresses in the film, allows high rate deposition of the thin film, and readily accommodates controlled heating of the substrate. There is already a strong history of using this process in fabricating thin films.

[0004] The resulting properties of the thin films depend strongly on uniform deposition of the aluminum scandium alloy. This imposes considerable demands on the properties ofthe sputtering targets and the alloys. The Al-Sc alloy system presents challenges for the manufacturing of sputter targets due to the presence of multiple brittle intermetallic phases and a propensity for segregation. The piezoelectric response of the thin film is strongly dependent upon the scandium content of the film, and so the overall morphology, microstructure, and chemistry of the scandium in the sputtering target is critical.

[0005] Previously, targets comprising the aluminum-scandium alloys suffered from deficiencies in physical / mechanical performance such as a non-uniform microstructure, areas of low density, and / or having defects leading to cracks which can cause arcing and / or particulation during sputtering, leadingto yield losses and reduced target lifetime.

[0006] Even in view of the known alloys and sputtering targets, the need exists for an uncomplicated, powder consolidating process to produce an Al-Sc alloy sputtering target that provides a uniform and fine microstructure while also providing high density, hardness, and fracture toughness.SUMMARY

[0007] In one embodiment, there is provided a durable sputtering targeting and processes for producing such durable targets. Targets, such as those described herein, may have a uniform microstructure to address the need for targets generating minimal sputtering arcs during magnetron sputtering and hence better performance. In one embodiment, the sputtering target may contain from 10 to 50 at% scandium. In one embodiment, the sputtering targets described herein are enriched in the Al3Sc phase, and may greater than 50% Al3Sc by weight as determined by x-ray diffraction. While the sputtering target may comprise metallic aluminum (i.e. Al phase) and / or AISc phase, the sputtering target may have low amounts of Al2Sc phase. It has been found by the inventors that sputtering targets with higher Al2Sc phase amounts may be more brittle and less durable. In one embodiment, the sputtering target may have a density of greater than or equal to 2.7 g / cc.

[0008] In one aspect, the process described herein relates to a process for producing a sputtering target comprising consolidating a first powder and a second powder to form the sputtering target. In one embodiment, the first powder has at least 90 wt% or more of analuminum powder that contains from 0 to 10 at% scandium. In some embodiments, the first powder may contain from 0 to 5 at% scandium. In one embodiment, the first powder is an aluminum powder having 0 at% scandium. In one embodiment, the second powder has at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium. In some embodiments, the second powder may contain from 30 at% to 60 at% scandium. In one embodiment, the sputtering target comprisingfrom 5 to 50 wt% of the first powder and from 50 to 95 wt% of the second powder. In one embodiment, the first powder and / or second powder, each independently, have a phase ratio of Al3Sc to (Al3Sc+Al2Sc), also referred to as Al3Sc / (Al3Sc+Al2Sc) ratio, of greater than or equal to 0.5, or in terms of ranges from 0.5 to 0.95. The first powder may have an average particle size ranging from 2 to 300 microns, preferably 25 microns to 250 microns, from 50 microns to 150 microns. The second powder may have an average particle size ranging from 1 micron to 200 microns, preferably from 20 microns to 100 microns. The first powder and / or second powder may each comprise spherical particles. The first powder may comprise metallic aluminum, i.e. x is 0, and may have less than or equal to 1000 ppm oxygen. The second powder is an alloy and thus may not contain metallic aluminum, and may have less than or equal to 1000 ppm oxygen and less than or equal to 1000 ppm metallic aluminum.

[0009] In one aspect, there is provided a sputtering target comprising an alloy of aluminum and scandium and containing from 10 at% to 50 at% scandium, the sputtering target having an oxygen content of less than or equal to 2000 ppm and the sputtering target having from 60 to 75% of an Al3Sc phase, from 15 to 25% of an AISc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

[0010] In one aspect, there is provided a process for producing a sputtering target, the process comprising providing a first powder having at least 90 wt% or more of an aluminum powder that contains from 0 to 10 at% scandium, heating a second metal source comprising from 25 at% to 80 at% scandium, contacting the heated second metal source with an atomization gas to form a second powder, and consolidating the first powder and the second powder to form the sputtering target.

[0011] In one aspect, there is provided a process for producing a sputtering target, the process comprising heating a first metal source comprising from 0 to 10 at% scandium, contacting the heated first metal source with an atomization gas to form a first powder, heating a second metal source comprising from 25 at% to 80 at% scandium, contacting the heated second metal source with an atomization gas to form a second powder, and consolidating the first powder and the second powder to form the sputtering target.

[0012] In one aspect, there is provided a process for producing a sputtering target, the process comprising heating a first metal source comprising from 0 to 10 at% scandium, contacting the heated first metal source with an atomization gas to form a first powder, contacting a second metal source with a grinding media to form a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium, and consolidating the first powder and the second powder to form the sputtering target.

[0013] In one aspect there is provided a process for producing a sputtering target, the process comprising providing a first powder having at least 90 wt% or more of an aluminum powder that contains from 0 to 10 at% scandium, contacting a second metal source with a grinding media to form a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium, and consolidating the first powder and the second powder to form the sputtering target.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Afurther understanding of the nature and advantages of the disclosed technology may be realized by reference to the remaining portions of the specification and the drawings.

[0015] FIG. 1 is a photomicrograph of a sputtering target having 25 at% scandium accordingto Example 1 ;

[0016] FIG. 2 is a photomicrograph of a sputtering target having 19.2 at% scandium accordingto Example 2;

[0017] FIG. 3 is a photomicrograph of a sputtering target having 19.2 at% scandium accordingto Example 3;

[0018] FIG. 4 is a photomicrograph of a sputtering target having 19.2 at% scandium accordingto Example 4;

[0019] FIG. 5 is a photomicrograph of a sputtering target having 19.2 at% scandium accordingto Example 5;

[0020] FIG. 6a-6c are photomicrographs of a sputtering target having 19.2 at% scandium accordingto Example 6;

[0021] FIG. 7 is a graph of the AISc phases at different temperature;

[0022] FIG. 8 is a photomicrograph of a sputtering target having 20.5 at% scandium accordingto Example 7;

[0023] FIG. 9 is a photomicrograph of a sputtering target having 20.5 at% scandium accordingto Example 8;

[0024] FIG. 10 is a photomicrograph of a sputtering target having 20.5 at% scandium accordingto Example 9;

[0025] FIG. 11 is a photomicrograph of a sputtering target having 20.5 at% scandium accordingto Example 10;

[0026] FIG. 12 is a photomicrograph of a sputtering target having 30 at% scandium accordingto Example 11 ;

[0027] FIG. 13 is a photomicrograph of a sputtering target having 30 at% scandium accordingto Example 12;

[0028] FIG. 14 is a photomicrograph of a sputtering target having 30 at% scandium accordingto Example 13;

[0029] FIGS. 15a and 15b are photomicrographs of a sputtering target having 30 at% scandium accordingto Example 14; and

[0030] FIGS. 16a-16c are photomicrographs of a sputtering target through thickness having 40 at% scandium accordingto Example 15.DETAILED DESCRIPTION

[0031] Existing Al-Sc alloy sputtering targets suffer from problems due to non-uniform microstructures and / or defects, e.g., cracks due to challenges associated with brittle (intermetallic) phase(s) common to the Al-Sc alloys.

[0032] It has now been discovered that the disclosed processes synergistically combine to provide for a microstructure that has the desired hardness and fracture toughness. In one embodiment, the process forms a uniform and fine microstructure. To achieve the preferred microstructure, the embodiments describe processed for producing Al-Sc alloys by consolidating at least two powder compositions having different amounts of scandium. One of the powders may comprise at least 90% of an aluminum powder that contains from 0 to 10 at% scandium, e.g. from 0 to 5 at% scandium or 0 at% scandium. The other powder may comprise at least 90% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium. Surprisingly, it has been found that consolidation of at least two different powders provides a predominance of preferred phases, in particular a predominance of Al3Sc. In one embodiment, the target has a predominance of Al3Sc in targets having scandium content from 10 at% to 50 at%, and in particular for those targets having a scandium content of greater than 25 at%. The consolidation of at least two different powders may also suppress other phases such as Al2Sc. Previous efforts obtain a predominance of Al3Sc in targets having scandium content of greater than 25 at% were limited by the binary Al-Sc phase diagrams. Processes herein further include that the different powders are consolidated by hot pressing, hot isostatic pressing, and / or spark plasma sintering to form dense, sintered sputtering targets of hardness and uniform phase distribution. In one embodiment, the sintered sputtering targets may have ductility.

[0033] In one embodiment, there is provided a sputtering target comprising an alloy of aluminum and scandium and containingfrom 10 at% to 50 at% scandium, and the sputtering target having from 60 to 75% of an Al3Sc phase, from 15 to 25% of an Al2Sc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

[0034] Sputtering targets made from the processes herein may be used to deposit thin films onto a substrate. The piezoelectric properties of an individual device on the substrate are critically dependent upon the local stoichiometry of the film contained within an individual device. Hence the distribution of the scandium and / or scandium-containing phases through an Al-Sc sputtering target should be as finely distributed and as uniform as possible. This is important because if the amount of scandium being sputtered from the target varies over the life of the target, the piezoelectric properties of the deposited film will change over the life of the target, resulting in device performance inconsistencies and resulting product yield loss. Further, it has been found that certain intermetallic phases are preferred (e.g., Al3Sc) over others (e.g., Al2Sc) imparting certain favorable properties such as hardness and / or fracture toughness (e.g., resistance to cracking). Thus, evenly distributed phases within the target microstructure is also necessary to provide targets for long life and high performance (crack resistant, minimal arcing behavior, and minimal particulation). Processing, as well as properties and characteristics, of the sputtering targets are discussed below.

[0035] One of the piezoelectric materials in electro-acoustic applications is aluminum nitride (AIN). However, AlN-based devices have a rather low piezoelectric coefficient d33= 5.5 pC / N, and a limited electromechanical coupling of 7%. These properties are significantly improved by adding scandium (Sc) in the wurtzite structure AIN. It was shown that the incorporation of Sc into AIN allows an increase up to 400% of the piezoelectric coefficient d33. Moreover, the material electromechanical coupling of the Ali.xScxN is expected to increase 200% with Sc concentration x = 0.3. The piezoelectric AlScN will remain the same hexagonal wurtzite structure as AIN with c-axis orientation up to x = 0.5, so that the max doping Sc in Ali.xScxN could be up to 50%.

[0036] The AlScN is now gaining more attention in the microelectronic industry for its use as a piezoelectric filter in phones requiring high bandwidths at high frequencies. These filters, also known as bulk acoustic waves (BAW), prevent and protect frequencies within a device at around 900 MHz for bandwidths up to 5 GHz. More specifically, BAW resonators implement a thin layer of piezoelectric material that is deposited through sputtering andare placed between two electrodes where an acoustic wave is then generated from the resulting electric field.

[0037] AlScN thin films are normally produced by reactive sputtering from AISc alloy targets. The extrinsic properties required of any AlScN thin film are similar: the deposit should be homogeneous in chemistry, exhibit consistent metallurgical structure, be uniform in thickness, and adequately coat all feature on the substrate. The sputtering performance of AISc targets must be predictable and consistent: performance must not vary significantly through the life of the target, nor should be sputtering reliability deviate from target to target. AISc sputtering targets themselves refer to the bulk material that is deposited onto a substrate with mainly being manufactured through casting method. The quality of deposited film is directly affected by the quality of the target that has been cast, with common defects being porosity, non-homogeneity of both composition and microstructure due to a large solidification temperature range (AT up to 640 °C) in Al-Sc system (<25at%Sc), and to a great difference between the melting temperatures of Sc and Al. Impurities and oxides are other general concerns. The composition of these targets plays a huge role in the success of the sputtering process, and therefore the overall viability of the filter itself. Impurities are a common detrimental component that target material often contains as it tends to dampen the piezoelectric effect of the Al-Sc alloy. Another common defect seen in target material is porosity. During sputtering, porosity can prevent uniform deposition rates as well as result in particulation.

[0038] Powder metallurgy (PM) is a relevant alternative route to product large sized (diameter) targets, which offers the potential for minimizing porosity and non-uniformity of composition and microstructure, and potentially for reducing overall cost of the final targets made by conventional ingot metallurgy.

[0039] The disclosure relates to processes for producing Al-Sc alloy sputtering targets by consolidating at least two powders having different amounts of scandium to form a high purity aluminum rare earth sputtering target. The aluminum rare earth sputtering target may have a 99% purity or greater based on the aluminum and scandium content. In one embodiment, there is provided a high purity aluminum rare earth sputtering target havingfrom 15 at% to 50 at% scandium, wherein the phases comprise an Al phase, AISc phase and an Al3Sc phase. Preferably, Al2Sc phase is not present or is minimized. Preferably, the aluminum sputtering target may have from 12.5 at% to 45 at% scandium, or more preferably 18.5 at% to 43 at% scandium, wherein the Al3Sc phase is more predominate than the Al2Sc phase. The process described herein are use a powder approach to avoid the limitations of casting process.

[0040] In one embodiment, atomized powder may be used for the different powders that are consolidated to form the target. In one embodiment, the atomizing may comprise a gas atomization process, centrifugal atomization process, plasma atomization, impulse atomization, ultrasonic gas atomization, plasma spray pyrolysis, and explosive atomization. Centrifugal atomization process may be preferably used to obtain atomized powder. Atomizing may be conducted by smelting a metal or metal alloy to form a liquid metal stream that is atomized by an inert gas flow and collected as an atomized powder. The inert gas flow may be a high pressure using argon, nitrogen, and / or helium. The atomization process may be conducted in a vacuum. In one embodiment, each powder may be prepared by a separate atomization process.

[0041] In one embodiment, the atomized powders herein comprise spherical particles or nearly spherically particles. Preferably, the morphologies of the powders are predominantly spherical with some degree of satellite particles. Spherical particles demonstrate good flowability. In one embodiment, the atomized powders have a fine average size as well as a narrow particle size distribution (PSD). In one embodiment, the PSD is narrow whereby the D50 is from 50 to 150, e.g., from 60 microns to 140 microns, from 80 microns to 120 microns, or from 90 microns to 100 microns. In one embodiment, the atomized powders, and in particular the spherical particles, may have internal pores. Processes herein further include that the atomized powders are consolidated by hot pressing and / or spark plasma sintering to form dense, sintered sputtering targets of hardness and uniform phase distribution.

[0042] In one embodiment, the powder may be obtained by a mechanical process such as milling, ball milling, grinding, stirring, rolling, vibrating, sonicating, or a combinationthereof. Preferably ball milling may be used to obtain either the first or second powders or both powders. The mechanical process may produce a spherical powder, irregular (non- spherical) powder, plate-like powder or flake-like powder.

[0043] In one embodiment, the grinding media used in the mechanical process may be hardened steel, stainless steel, tungsten carbide, alumina ceramic, zirconia ceramic (includingyttria stabilize zirconia), silicon nitride, agate, polystyrene, methacrylate, polycarbonate or combinations thereof. The grinding media is of sufficient size to obtain the desired powder.

[0044] Ball milling the powder mixture may be in the presence of an alumina grinding media and a solvent to form a powder slurry.

[0045] In one embodiment, the first powder may be an aluminum powder or an aluminum scandium alloy powder. The first powder may comprise at least 90 wt% or more of an aluminum powder or an aluminum scandium alloy powder, e.g., at least 95 wt% or more, at least 98 wt% or more. Accordingly, it is preferable that the first powder is entirely the aluminum powder orthe aluminum scandium alloy powder. In one embodiment, the first powder may be prepared by an atomizing process and it is less preferred to use a mechanical process.

[0046] In one embodiment, the first powder contains more aluminum whether as an aluminum powder or an aluminum scandium alloy powder having a low amount of scandium as compared to the second powder. The aluminum from the first powder may react during consolidation with Al2Sc and / or AISc phases to form Al3Sc. By adjustingthe amount of the first powder, the process may improve the mechanical properties to provide sputtering targets that are less susceptible to cracking by increasing the Al3Sc in the phase structure.

[0047] In one embodiment, the first powder may be an aluminum powder comprising metallic aluminum. Accordingly, the first powder may be an aluminum powderthat contains 0 at% scandium. The metallic aluminum may be of high purity, having a purity of greater than or equal to 95%, e.g., greater than or equal to 97%, greater than or equal to 98.5%, greater than or equal to 99%, or greater than or equal to 99.5%. The metallicaluminum has minimal amounts and preferably very low amounts of alumina. In such embodiments, the process uses two different powders and the scandium is provided by the second powder.

[0048] In one embodiment, first powder is an aluminum scandium alloy powder that comprises scandium. For purposes of the present invention, the first powder may contain from 0 to 10 at% scandium, e.g., from 0.1 to 10 at% scandium, from 0.1 to 8 at% scandium, from 0.1 to 7.5 at% scandium, from 0.1 to 6 at% scandium, from 0.1 to 5.5 at% scandium, from 0.1 to 5 at% scandium, from 0.5 to 5 at% scandium, from 1 to 5 at% scandium, from 1 .5 to 5 at% scandium, or from 2.5 to 5 at% scandium. In one aspect of the present invention, the process uses two different powders and it is preferred that one of the powder, herein labelled as the first powder, contains a lower atomic percentage of scandium. In one aspect of the present invention, the process uses two different powders and it is preferred that one of the powder, herein labelled as the first powder, contains a higher atomic percentage of aluminum.

[0049] When the first powder contains small amounts of scandium, the phases in the second powder may be binary intermetallic phases such as AISc and Al3Sc. It is preferred that the first powder contains insignificant or no amounts of Al2Sc. In one aspect, there is provided a process for producing a sputtering target comprising consolidating a first powder that contains insignificant or no amounts of Al2Sc with a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium to form the sputtering target.

[0050] The first powder may have an average particle size ranging from 2 microns to 300 microns, e.g., from 5 microns to 275 microns, from 25 microns to 250 microns, from 30 microns to 225 microns, from 35 microns to 200 microns, from 40 microns to 175 microns or from 50 microns to 150 microns. When the particle size is less than 2 microns the particles may tend to agglomerate. While larger particles, which are over 300 microns are not preferred due to processing inefficiencies upon consolidation.

[0051] The first powder disclosed in processes herein should contain as little oxygen as possible to avoid deleterious effects in sputtering. In some embodiments, the first powdercomprises less than 1000 ppm oxygen, e.g., less than 950 ppm, less than 900 ppm, less than 850 ppm, or less than 750 ppm. In terms of ranges, the oxygen content of the first powder is from 0 to 1000 ppm, e.g., from 10 ppm to 1000 ppm, from 25 ppm to 950 ppm, from 50 ppm to 900 ppm, from 75 ppm to 850 ppm or from 100 ppm to 750 ppm.

[0052] Preferably, the first powder is of high purity and contains as few contaminants as possible. Both the metallic aluminum and aluminum scandium alloy may contain low amounts of transition metal elements, e.g., less than 1000 ppm or more preferably less than 100 ppm. In particular, the amount of iron should be minimized. Both the metallic aluminum and aluminum scandium alloy has a halide content from 0 to 100 ppm, e.g., from 0 to 50 ppm or from 0 to 10 ppm or from 0 to 1 ppm. Appropriately, the aluminum and aluminum scandium alloy may comprise insignificant to no amounts of halides such as fluoride and chloride.

[0053] Turning to the second powder, which is consolidated with the first powder, the second powder may be aluminum scandium alloy powder. As indicated above, the second powder may be produced as an atomized powder or through mechanical process such as ball milling or other process described herein. In general, the scandium content of the second powder is higher than the first powder. In one embodiment, the second powder has at least 90 wt% or more of an aluminum scandium powder, e.g., at least 95% or more, at least 98% or more or at least 99% or more. In one embodiment, the second powder may be essentially an aluminum scandium powder. The aluminum scandium powder for the second powder may contain from 25 at% to 80 at% scandium, e.g., from 30 at% to 70 at%, from 30 at% to 65 at%, from 35 at% to 50 at%, from 35 at% to 45 at%, or from 38 at% to 43 at%. In one embodiment, the second powder has a phase ratio of Al3Sc phase to the combined phases of Al3Sc and Al2Sc (the “Al3Sc / (Al3Sc+Al2Sc) ratio”) of greater than or equal to 0.5, e.g., greater than 0.55, greater than 0.6, greater than 0.62, greater than 0.63, greater than 0.64, or greater than 0.65. Each phase is measured by the photomicrograph using techniques like scanning electron microscopy (SEM) or X-ray energy dispersive spectroscopy (EDS). In terms of ranges, the Al3Sc / (Al3Sc+Al2Sc) ratio may be from 0.5 to 0.95, e.g., from 0.5 to 0.9, from 0.5 to 0.75, from 0.55 to 0.76 or from 0.6 to 0.72. In oneembodiment, provided that the second powder contains from 25 at% to 33 at% scandium, the Al3Sc / (Al3Sc+Al2Sc) ratio may be greater than or equal to 0.5. In one embodiment, provided that the second powder contains at least 30 at% or more scandium, the Al3Sc / (Al3Sc+Al2Sc) ratio may be greater than or equal to 0.5.

[0054] In one embodiment, the second powder may have an average particle size ranging from 1 microns to 200 microns, e.g., from 1 microns to 175 microns, from 5 microns to 170 microns, from 10 microns to 150 microns or from 20 microns to 100 microns. In one embodiment, the second powder may be smaller in terms of average particle size than the first powder.

[0055] Similar to the first powder, the second powder preferably contains as little oxygen as possible to avoid deleterious effects in sputtering. In some embodiments, the second powder comprises less than 1000 ppm oxygen, e.g., less than 950 ppm, less than 900 ppm, less than 850 ppm, or less than 750 ppm. In terms of ranges, the oxygen content of the second powder is from 0 to 1000 ppm, e.g., from 10 ppm to 1000 ppm, from 25 ppm to 950 ppm, from 50 ppm to 900 ppm, from 75 ppm to 850 ppm or from 100 ppm to 750 ppm.

[0056] In one embodiment, the second powder may be an aluminum scandium alloy powder. As indicated herein the second powder may also be an aluminum scandium alloy comprising an amount of scandium being from 25 at% to 80 at%, e.g., from 30 at% to 70 at%, from 30 at% to 65 at%, from 35 at% to 50 at%, from 35 at% to 45 at%, or from 38 at% to 43 at%.

[0057] Preferably, the second powder is of high purity and contains as few contaminants as possible. In one embodiment, the second powder may comprise less than or equal to 1000 ppm metallic aluminum. The aluminum scandium alloy may contain low amounts of transition metal elements, e.g., less than 1000 ppm or more preferably less than 100 ppm. In particular, the amount of iron should be minimized. The aluminum scandium alloy may comprise insignificantto no amounts of halides such as fluoride and chloride. In one embodiment, the aluminum scandium alloy has a halide content from 0 to 100 ppm, e.g., from 0 to 50 ppm or from 0 to 10 ppm or from 0 to 1 ppm.

[0058] The process described herein relates to a process for producing a sputtering target comprising consolidating a first powder and a second powder to form the sputtering target. The consolidation is conducted under conditions that are not susceptible to cracking or subsequent machining. Consolidating includes vacuum hot pressing, inert gas hot pressing, hot isostatic pressing, and / or spark plasma sintering. In one embodiment, 5 wt% to 95 wt% of the first powder may be consolidated with 5 wt% to 95 wt% of the second powder. In one embodiment, the consolidation may use more second powder than first powder, and the process may consolidate 5 wt% to 50 wt% of the first powder with 50 wt% to 95 wt% of the second powder, and more preferably from 30 to 50 wt% of the first powder and from 50 wt% to 70% of the second powder. In another embodiment, the consolidation may use more first powder than second powder, and the process may consolidate 50 wt% to 95 wt% of the first powder may be consolidated with 5 wt% to 50 wt% of the second powder, and more preferably from 50 to 70 wt% of the first powder and form 30 wt% to 50% of the second powder.

[0059] Hot pressing or hot isostatic pressing may include heating (e.g., sintering to provide densification) to certain temperatures, times, and at certain pressures. In some embodiments, hot pressing is conducted at a temperature from 500 °C to 1250 °C, e.g., from 600 °C to 1250 °C, from 650 °C to 1250 °C, from 1050 °C to 1250 °C or 1100 °C to 1250 °C. In some embodiments, the hot pressing is conducted at a low temperature from 500 °C to 690 °C, e.g., from 510 °C to 675 °C, from 525 °C to 650 °C, from 550 °C to 625 °C. When the temperature is too low for the hot pressing, the density of the sputter target may be insufficient. To avoid issues with insufficient density, hot pressing may be conducted at a temperature of greater than or equal to 500 °C, e.g., greater than 550 °C, greater than 600 °C, greater than 750 °C, greater than 900 °C, greater than 1000 °C, greater than 1050 °C or greater than 1100 °C. Generally higher temperatures during sintering increases density, but temperatures that exceed 1250 °C are prone to cracking. In terms of upper limits, hot pressing may be conducted at a temperature of less than or equal to 1250 °C, e.g., less than 1200 °C, less than 1150 °C, or less than 1000 °C.

[0060] In one embodiment, the first powder may be relatively soft and ductile as compared to the second powder. At lower consolidation temperatures, the first powder may function to adhere both the first powder and the second powder to produce a dense and ductile target. Preferably, the lower consolidation temperatures may also produce a target that is less susceptible to cracking.

[0061] In one embodiment, the heat treatment time for the hot pressing or hot isostatic pressing may be from 1 hour to 8 hours, e.g., from 2 hours to 6 hours or from 3 hours to 5 hours. In terms of lower limits, hot pressing may be conducted at a time of greater than 1 hour, e.g., greater than 2 hours or greater than 3 hours. In terms of upper limits, hot pressing may be conducted at a time of less than 8 hours, e.g., less than 6 hours or less than 5 hours. In certain embodiments, hot pressing is at a time of 4 hours.

[0062] In some embodiments, hot pressing or hot isostatic pressing may be conducted at a pressure within the range from 10 MPa to 250 MPa, e.g., from 10 MPa to 200 MPa, from 15 MPa to 190 MPa, or from 15 MPa to 45 MPa. In terms of lower limits, hot pressing may be conducted at a pressure of greater than 10 MPa, e.g., greater than 15 MPa or greater than 25 MPa. In terms of upper limits, hot pressing may be conducted at a pressure of less than 250 MPa, e.g., less than 225 MPa, less than 210 MPa, or less than 200 MPa. In certain embodiments, hot pressing is at a pressure of 15 MPa. In one embodiment, hot pressing may be conducted with a neutral sinter without pressure, or at atmospheric pressure. In some embodiments, the hot pressing may involve two cycles with the second cycle being at a highertemperature.

[0063] Hot pressing or hot isostatic pressing may be conducted in an inert atmosphere, e.g. in argon gas, reducing atmosphere, or vacuum atmosphere. Preferably, hot pressing or hot isostatic pressing may be conducted in an inert atmosphere.

[0064] Spark plasma sintering may include heating (e.g., sintering to provide densification) to certain temperatures, times, and at certain pressures. In some embodiments, spark plasma sintering is at a temperature from 500 °C to 1150 °C, e.g., from 600 °C to 1150 °C, from 750 °C to 1150 °C, from 900 °C to 1150 °C , from 950 °C to 1150 °C , from 1000 °C to 1100 °C. In terms of lower limits, spark plasma sintering may be conducted at atemperature of greater than or equal to 500 °C, e.g., greater than 600 °C, greater than 750 °C, greater than 900 °C, greater than 950 °C, greater than 1000 °C, greater than 1050 °C or greaterthan 1100 °C. In terms of upper limits, spark plasma sintering may be conducted at a temperature of less than 1100 °C, e.g., less than 1150 °C or less than 1100 °C.

[0065] In some embodiments, spark plasma sintering is at a time from 5 minutes to 1 hour, e.g., from 10 minutes to 40 minutes or from 15 minutes to 30 minutes. In terms of lower limits, spark plasma sintering may be conducted at a time of greater than 5 minutes, e.g., greater 10 minutes or greaterthan 15 minutes. In terms of upper limits, spark plasma sintering may be conducted at a time of less than 1 hour, e.g., less than 40 minutes or less than 30 minutes. In certain embodiments, spark plasma sintering is at a time of 10 minutes or22 minutes or 40 minutes.

[0066] In some embodiments, spark plasma sintering is at a pressure from 35 MPa to 75 MPa, e.g., from 45 MPa to 65 MPa, or from 50 MPa to 55 MPa. In terms of lower limits, spark plasma sintering may be conducted at a pressure of greater than 35 MPa, e.g., greater than 45 MPa or greater than 55 MPa. In terms of upper limits, spark plasma sintering may be conducted at a pressure of less than 75 MPa, e.g., less than 65 MPa or less than 55 MPa. In certain embodiments, spark plasma sintering is at a pressure of 45 MPa. In other embodiments, spark plasma sintering is at a pressure of 55 MPa. In yet other embodiments, spark plasma sintering is at a pressure of 65 MPa.

[0067] Spark plasma sintering may be conducted in an inert atmosphere, e.g. in argon gas, or in a vacuum, or in a reducing hydrogen gas mixture (i.e., forming gas).

[0068] After consolidation, the process may produce a sputtering target containing from 10 at% to 50 at% scandium, e.g., from 12.5 at% to 45 at% scandium, from 12.5 at% to 43 at% scandium, from 15 at% to 42 at% scandium, from 17.5 at% to 42 at% scandium, from 25 at% to 40 at% scandium. In one embodiment, the sputtering target may have the formula Ali.xScx, wherein x is from 0.1 to 0.5, 0.11 to 0.45, 0.12 to 0.43, 0.13 to 0.43, 0.15 to 0.42, 0.17 to 0.42, 0.25 to 0.4, or from 0.3 to 0.4. Aluminum comprises the balance of the sputtering target, and is generally greater than 50 at%.

[0069] The sputtering target may contain binary intermetallic phases such as Al3Sc, AISc, and Al2Sc. To achieve mechanical performance with less susceptibility to cracking the consolidation of the powders tends to promote the formation of Al3Sc. In one embodiment, the sputtering target has from 60 to 75% of an Al3Sc phase based on the total phases of the sputtering target, e.g., from 62 to 73% of an Al3Sc phase. In one embodiment, the sputtering target has from 15 to 25% of an AISc phase, based on the total phases of the sputtering target, e.g., from 17 to 23% of an AISc phase. In one embodiment, the sputtering target has from 5 to 15% of an Al phase, based on the total phases of the sputtering target, e.g., from 7 to 12% of an Al phase. To reduce the susceptibility to cracking the sputtering target may have less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target. More preferably, the Al2Sc phase may be from 0 to 5% based on the total phases of the sputtering target, or from 0.5 to 3.5%.

[0070] Upon consolidation, the aluminum scandium sputtering target has a composition comprising from 10 at% to 50 at% scandium and from 50 at% to 90% aluminum (optionally along with other elements), as detailed above. The sputtering target composition is consistent with the composition of the atomized powder used for consolidating. However, the phases present in the pressed target can change according to amount of first powder addition and the original composition of second powder, pressing parameters as temperature, pressure, time, and the like upon consolidating (via hot pressing or spark plasma spraying.) Sputtering targets as disclosed herein may contain free aluminum (Al), Al3Sc, Al2Sc, AISC, SC2O3, combinations thereof, and possibly trace other phases. Sputtering targets as disclosed herein may be devoid or substantially devoid of Al2O3and / or free Al.

[0071] The disclosed aluminum scandium alloy sputtering target has a microstructure characterized by a fine microstructure, desired phase components, and a uniform distribution of phases. Both of these characteristics provide for a sputtering target with high fracture toughness and durabilty that is less susceptible to cracking.

[0072] The sputtering targets comprising aluminum and scandium may have the following target densities and hardness. Both of these properties may be dependent upon target composition.

[0073] Sputtering targets comprising aluminum and scandium produced by the processes disclosed herein are dense, sintered targets. Targets disclosed herein have a density greater than or equal to 2.7 g / cm3. In some embodiments, the target has a density greater than 2.7 g / cm3, e.g., greater than 2.75 g / cm3, greater than 2.8 g / cm3, greater than 2.82 g / cm3, greater than 2.85 g / cm3, greater than 2.9 g / cm3, greater than 2.95 g / cm3, greater than 2.98 g / cm3, greater than 2.99 g / cm3, greater than 3.0 g / cm3, or greater than 3.03 g / cm3. The target may have a range from 2.7 g / cm3to 3.4 g / cm3, e.g., from 2.7 g / cm3to 3.1 g / cm3, 2.75 g / cm3to 3.0 g / cm3, or 2.75 g / cm3to 2.9 g / cm3. In some embodiments, the target has a density % greater than 90% based on the mix rule density, assuming no reaction between the aluminum powder and the aluminum scandium powder, e.g., greater than 91%, greater than 92%, greater than 93%, greater than 94%, greater than 95%, greater than 96%, greater than 97%, greater than 98%, greater than 99%, greater than 100%, or greater than 101%.

[0074] As mentioned above, the sputtering targets comprising aluminum and scandium may be of high purity, and contains as few contaminants as possible. Thus, the target disclosed in processes herein should contain as little oxygen as possible. In some embodiments, the target comprises less than or equal to 2000 ppm oxygen, e.g., less than 1750 ppm, less than 1500 ppm, less than 1250 ppm, or less than 1000 ppm. In terms of the ranges the oxygen may be from 0 ppm to 2000 ppm, e.g., from 0.01 ppm to 2000 ppm, from 0.1 ppm to 1750 ppm, from 0.5 to 1500 ppm, from 1 to 1250 ppm, from 5 to 1000 ppm.

[0075] The presence of transition metal elements, for example iron, should also be minimized. Thus, the target disclosed in processes herein contain as insignificant amounts of transition metal elements. In some embodiments, the powder comprises less than or equal to 2000 ppm metal elements, e.g., less than 1750 ppm, less than 1500 ppm, less than 1250 ppm, or less than 1000 ppm. In terms of the ranges the transition metalelements may be from 0 ppm to 2000 ppm, e.g., from 0.01 ppm to 2000 ppm, from 0.1 ppm to 1750 ppm, from 0.5 to 1500 ppm, from 1 to 1250 ppm, from 5 to 1000 ppm.

[0076] In some embodiments, the target disclosed in processes herein should contain as little free aluminum as possible. In some embodiments, the powder comprises less than or equal to 2000 ppm free aluminum, e.g., less than 1750 ppm, less than 1500 ppm, less than 1250 ppm, or less than 1000 ppm. In terms of the ranges the free aluminum may be from 0 ppm to 2000 ppm, e.g., from 0.01 ppm to 2000 ppm, from 0.1 ppm to 1750 ppm, from 0.5 to 1500 ppm, from 1 to 1250 ppm, from 5 to 1000 ppm.

[0077] In certain aspects, the target comprises less than 1000 ppm oxygen. In certain aspects, the target comprises less than 1000 ppm transition metal elements. In certain aspects, the target comprises less than 1000 ppm free aluminum.

[0078] Sputtering targets comprising aluminum and scandium produced by the processes disclosed herein may be soft, e.g. demonstrate a Hardness Rockwell B (HRB) from 50 to 100, e.g., from 60 to 90, from 70 to 88, or from 74 to 86, as measured according to ASTM E18-17e1.

[0079] The dimensions of the sputtering targets comprising aluminum and scandium are not particularly limited and may be adjusted as needed. In general, sputtering targets comprising aluminum and scandium may have a diameter of greaterthan 50 mm, e.g., greater than or equal to 100 mm, greater than 200 mm, greater than 300 mm, or greater than 400 mm. Thicknesses of the targets herein may be greater than or equal to 4 mm, e.g., greater than 5 mm, greater than 8 mm, or greater than 10 mm. The process may be used for thick targets up to width of the target. In certain embodiments, the target of the process herein has a diameter of greater than or equal to 100 mm and a thickness of greater than or equal to 4 mm.

[0080] For the purposes of examples herein, “as-cast” or “casting” refer to comparative examples made by conventional means. Powder metallurgy (PM), gas atomized (GA), hot presses (HP), and spark plasma sintering (SPS) refer to inventive examples herein.

[0081] In some embodiments, any or some of the components disclosed herein may be considered optional. In some cases, the disclosed compositions may expressly excludeany or some of the aforementioned components or process steps in this description, e.g., via claim language. For example claim language may be modified to recite that the disclosed compositions do not utilize or comprise one or more of the aforementioned impurities or phases, e.g., the claim language may be modified to recite that the disclosed targets do not comprise Al2Sc phase. Such negative limitations are contemplated, and this text serves as support for negative limitations for components, steps, and / or features.

[0082] Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In the drawings and the following description below, it is to be understood that like numeric designations refer to components of like function.

[0083] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0084] As used in the specification and in the claims, the term "comprising" may include the embodiments "consisting of" and "consisting essentially of." The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or words that require the presence of the named ingredients / components / steps and permit the presence of other ingredients / components / steps. However, such description should be construed as also describing compositions, articles, or processes as "consisting of" and "consisting essentially of" the enumerated ingredients / components / steps, which allows the presence of only the named ingredients / components / steps, along with any impurities that might result therefrom, and excludes other ingredients / components / steps.

[0085] Numerical values in the specification and claims of this application should be understood to include numerical values which are the same when reduced to the same number of significant figures and numerical values which differ from the stated value by less than the experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0086] ALL ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range of “from 2 grams to 10 grams” is inclusive of the endpoints, 2 grams or 10 grams, and all the intermediate values).

[0087] As used herein, “greater than” and “less than” limits may also include the number associated therewith. Stated another way, “greater than” and “less than” may be interpreted as “greater than or equal to” and “less than or equal to.” It is contemplated that this language may be subsequently modified in the claims to include “or equal to.” For example, “greater than 1 .0 mm” may be interpreted as, and subsequently modified in the claims as “greater than or equal to 1 .0 mm.”

[0088] When a material is described as having an average particle size or average particle size distribution, which is defined as the particle diameter at which a cumulative percentage of 50% (by volume) of the total number of particles are attained. In other words, 50% of the particles have a diameter above the average particle size, and 50% of the particles have a diameter below the average particle size. The size distribution of the particles will be Gaussian, with upper and lower quartiles at 25% and 75% of the stated average particle size, and all particles being less than 150% of the stated average particle size.

[0089] The process steps described herein refer to temperatures, and, unless provided for, this refers to the temperature attained by the material that is referenced, rather than the temperature at which the heat source (e.g. furnace, oven) is set. The term “room temperature” refers to a range from 20°C to 25°C (68°F to 77°F).

[0090] The term “about” can be used to include any numerical value that can vary without changing the basic function of that value. When used with a range, “about” also discloses the range defined by the absolute values of the two endpoints, e.g. “about 25 at% to about 80 at%” also discloses the range “from 25 at% to 80 at%.” The term “about” may refer to plus or minus 10% of the indicated number.

[0091] The present disclosure has been described with reference to exemplary embodiments. Obviously, modifications and alterations will occur to others upon reading and understandingthe preceding detailed description. It is intended that the presentdisclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof. In some embodiments, any or some of the steps or components disclosed herein may be considered optional. In some cases, any or some of the aforementioned items in this description may be expressly excluded, e.g., via claim language. For example claim language may be modified to recite additional process steps.

[0092] Embodiment one is a process for producing a sputtering target, the process comprising providing a first powder having at least 90 wt% or more of an aluminum powder that contains from 0 to 10 at% scandium, providing a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium, and consolidating the first powder and the second powder to form the sputtering target.

[0093] Embodiment two is the process of embodiment one, wherein 5 wt% to 95 wt% of the first powder is consolidated with 5 wt% to 95% of the second powder.

[0094] Embodiment three is the process of any one of embodiments one or two, wherein 5 wt% to 50 wt% of the first powder is consolidated with 50 wt% to 95% of the second powder.

[0095] Embodiment four is the process of any one of embodiments one to three, wherein 50 wt% to 95 wt% of the first powder is consolidated with 5 wt% to 50% of the second powder.

[0096] Embodiment five is the process of any one of embodiments one to four, wherein the first powder has an average particle size (d50) ranging from 2 microns to 300 microns, preferably from 50 microns to 150 microns.

[0097] Embodiment six is the process of any one of embodiments one to five, wherein the second powder has an average particle size (d50) ranging from 1 micron to 200 microns, preferably from 20 microns to 100 microns.

[0098] Embodiment seven is the process of any one of embodiments one to six, wherein the second powder has an Al3Sc / (Al3Sc+Al2Sc) ratio of greater than or equal to 0.5.

[0099] Embodiment eight is the process of any one of embodiments one to seven, wherein the first powder or the second powder comprises less than or equal to 1000 ppm oxygen.

[0100] Embodiment nine is the process of any one of embodiments one to eight, wherein the second powder comprises less than or equal to 1000 ppm metallic aluminum.

[0101] Embodiment ten is the process of any one of embodiments one to nine, wherein the sputtering target has from 60 to 75% of an Al3Sc phase, from 15 to 25% of an AISc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

[0102] Embodiment eleven is the process of any one of embodiments one to ten, wherein the first powder is provided by heating a first metal source comprising from 0 to 10 at% scandium and contactingthe heated first metal source with an atomization gas to form a first powder.

[0103] Embodiment twelve is the process of any one of embodiments one to eleven, wherein the second powder is provided by heating a second metal source comprising from 25 at% to 80 at% scandium and contactingthe heated second metal source with an atomization gas to form a second powder.

[0104] Embodiment thirteen is the process of any one of embodiments one to eleven, wherein the second powder is provided by contacting a second metal source with a grinding media to form a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium.

[0105] Embodiment fourteen is the process of any one of embodiments one to thirteen, wherein the consolidating includes hot pressing, hot isostatic pressing, or spark plasma sintering.

[0106] Embodiment fifteen is the process of any one of embodiments one to fourteen, wherein the first powder comprises from 0 to 5 at% scandium.

[0107] Embodiment sixteen is the process of any one of embodiments one to fifteen, wherein the second powder comprises from 30 at% to 60 at% scandium.

[0108] Embodiment seventeen is the process of any one of embodiments one to sixteen, wherein the sputtering target has a density of greater than or equal to 2.7 g / cc.

[0109] Embodiment eighteen is the process of any one of embodiments one to seventeen, wherein the sputtering target has an oxygen content less than or equal to 2000 ppm.

[0110] Embodiment nineteen is the process of any one of embodiments one to eighteen, wherein the first powder comprises spherical particles.

[0111] Embodiment twenty is the process of any one of embodiments one to nineteen, wherein the second powder comprises spherical particles.

[0112] Embodiment twenty-one is the process of any one of embodiments one to twenty, wherein the sputtering target comprises Al3Sc and / or Al2Sc.

[0113] Embodiment twenty-two is the process of embodiment twenty-one, wherein the sputtering target further comprises Sc2O3.

[0114] Embodiment twenty-three is the process of embodiments twenty-two, wherein the sputtering target is substantially devoid of Al2O3.

[0115] Embodiment twenty-four is the process of any one of embodiments one to twenty- three, wherein the sputtering target has a diameter of greater than 100mm and a thickness greaterthan or equal to 4 mm.

[0116] Embodiment twenty-five is the process of embodiment twenty-four, wherein the sputtering target comprises greater than 50% Al3Sc by weight as determined by x-ray diffraction.

[0117] Embodiment twenty-six is the process of embodiment twenty-five, wherein the sputtering target comprises AlSc.

[0118] Embodiment twenty-seven is the process of any one of embodiments one to twenty-six, wherein the sputtering target is less susceptible to cracking.

[0119] Embodiment twenty-eight is a sputtering target produced by the process of any one of embodiments one to twenty-seven, the sputtering target comprising an alloy of aluminum and scandium and containingfrom 10 at% to 50 at% scandium, the sputtering target having an oxygen content of less than or equal to 2000 ppm and the sputtering target having from 60 to 75% of an Al3Sc phase, from 15 to 25% of an AlSc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

[0120] Embodiment twenty-nine is a sputtering target produced by the process of any one of embodiments one to twenty-seven, the sputtering target comprising an alloy of aluminum and scandium and containing 12.5 at% to 45 at% scandium, the sputtering target having an oxygen content of less than or equal to 2000 ppm and the sputtering target having from 62 to 73% of an Al3Sc phase, from 17 to 23% of an AISc phase, from 7 to 12% of an Al phase, and from 0.5 to 3.5% of an Al2Sc phase, based on the total phases of the sputtering target.

[0121] Embodiment thirty is a process for producing a sputtering target, the process comprising providing a first powder having at least 90 wt% or more of an aluminum powder that contains from 0 to 10 at% scandium, heating a second metal source comprisingfrom 25 at% to 80 at% scandium, contacting the heated second metal source with an atomization gas to form a second powder, and consolidating the first powder and the second powder to form the sputtering target.

[0122] Embodiment thirty-one is a process for producing a sputtering target, the process comprising heating a first metal source comprising from 0 to 10 at% scandium, contacting the heated first metal source with an atomization gas to form a first powder, heating a second metal source comprising from 25 at% to 80 at% scandium, contacting the heated second metal source with an atomization gas to form a second powder, and consolidating the first powder and the second powder to form the sputtering target.

[0123] Embodiment thirty-two is a process for producing a sputtering target, the process comprising heating a first metal source comprising from 0 to 10 at% scandium, contacting the heated first metal source with an atomization gas to form a first powder, contacting a second metal source with a grinding media to form a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium, and consolidating the first powder and the second powder to form the sputtering target.

[0124] Embodiment thirty-three is a process for producing a sputtering target, the process comprising providing a first powder having at least 90 wt% or more of an aluminum powder that contains from 0 to 10 at% scandium, contacting a second metal source with a grindingmedia to form a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium, and consolidatin the first powder and the second powder to form the sputtering target.

[0125] Embodiment thirty-four is the process of any one of embodiments thirty to thirty- three, wherein 5 wt% to 95 wt% of the first powder is consolidated with 5 wt% to 95% of the second powder.

[0126] Embodiment thirty-five is the process of any one of embodiments thirty to thirty- three wherein 5 wt% to 50 wt% of the first powder is consolidated with 50 wt% to 95% of the second powder.

[0127] Embodiment thirty-six is the process of any one of embodiments thirty to thirty- three wherein 50 wt% to 95 wt% of the first powder is consolidated with 5 wt% to 50% of the second powder.

[0128] Embodiment thirty-seven is the process of any one of embodiments thirty to thirty- three wherein the first powder comprises from 0 to 5 at% scandium.

[0129] Embodiment thirty-eight is the process of any one of embodiments thirty to thirty- three, wherein the second powder comprises from 30 at% to 60 at% scandium.

[0130] Embodiment thirty-nine is the process of any one of embodiments thirty to thirty- three, wherein the sputtering target has a density of greater than or equal to 2.7 g / cc.

[0131] Embodiment forty is the process of any one of embodiments thirty to thirty-three, wherein the sputtering target has an oxygen content less than or equal to 2000 ppm.

[0132] Embodiment forty-one is the process of any one of embodiments thirty to thirty- three, wherein the second powder has an Al3Sc / (Al3Sc+Al2Sc) ratio of greater than or equal to 0.5.

[0133] Embodiment forty-two is the process of any one of embodiments thirty to thirty- three, wherein the first powder has an average particle size (d50) ranging from 2 microns to 300 microns.

[0134] Embodiment forty-three is the process of any one of embodiments thirty to thirty- three, wherein the first powder has an average particle size (d50) ranging from 50 microns to 150 microns.

[0135] Embodiment forty-four is the process of any one of embodiments thirty to thirty- three, wherein the second powder has an average particle size (d50) ranging from 1 micron to 200 microns.

[0136] Embodiment forty-five is the process of any one of embodiments thirty to thirty- three, wherein the second powder has an average particle size (d50) ranging from 20 microns to 100 microns.

[0137] Embodiment forty-six is the process of any one of embodiments thirty to thirty- three, wherein the first powder comprises spherical particles.

[0138] Embodiment forty-seven is the process of any one of embodiments thirty to thirty- three, wherein the second powder comprises spherical particles.

[0139] Embodiment forty-eight is the process of any one of embodiments thirty to thirty- three, wherein the first powder comprises less than or equal to 1000 ppm oxygen.

[0140] Embodiment forty-nine is the process of any one of embodiments thirty to thirty- three, wherein the second powder comprises less than or equal to 1000 ppm oxygen.

[0141] Embodiment fifty is the process of any one of embodiments thirty to thirty-three, wherein the second powder comprises less than or equal to 1000 ppm metallic aluminum.

[0142] Embodiment fifty-one is the process of any one of embodiments thirty to thirty- three, wherein consolidating includes hot pressing.

[0143] Embodiment fifty-two is the process of any one of embodiments thirty to thirty- three, wherein consolidating includes hot isostatic pressing.

[0144] Embodiment fifty-three is the process of any one of embodiments thirty to thirty- three, wherein consolidating includes spark plasma sintering.

[0145] Embodiment fifty-four is the process of any one of embodiments thirty to thirty- three, wherein the sputtering target comprises Al3Sc and / or Al2Sc.

[0146] Embodiment fifty-five is the process of embodiment fifty-four, wherein the sputtering target further comprises Sc2O3.

[0147] Embodiment fifty-six is the process of embodiment fifty-four, wherein the sputtering target is substantially devoid of Al2O3.

[0148] Embodiment fifty-seven is the process of any one of embodiments thirty to thirty- three, wherein the sputtering target has a diameter of greater than 100mm and a thickness greaterthan or equal to 4 mm.

[0149] Embodiment fifty-eight is the process of embodiment fifty-seven, wherein the sputtering target comprises greater than 50% Al3Sc by weight as determined by x-ray diffraction.

[0150] Embodiment fifty-nine is the process of embodiment fifty-eight, wherein the sputtering target comprises AlSc.

[0151] Embodiment sixty is a sputtering target produced by the process of any one of embodiments any one of embodiments thirty to fifty-nine, wherein the sputtering target has from 60 to 75% of an Al3Sc phase, from 15 to 25% of an AlSc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

[0152] Embodiment sixty-one is the sputtering target of embodiment sixty, wherein the sputtering target has from 62 to 73% of an Al3Sc phase.

[0153] Embodiment sixty-two is the sputtering target of embodiment sixty-one, wherein the sputtering target has from 17 to 23% of an AlSc phase.

[0154] Embodiment sixty-three is the sputtering target of embodiment sixty-two, wherein the sputtering target has from 7 to 12% of an Al phase.

[0155] Embodiment sixty-four is the sputtering target of embodiment sixty-three, wherein the sputtering target has from 0.5 to 3.5% of an Al2Sc phase.

[0156] Embodiment sixty-five is the sputtering target of embodiment sixty-four, wherein the sputtering target is less susceptible to cracking.

[0157] Embodiment sixty-six is a sputtering target comprising an alloy of aluminum and scandium and containing from 10 at% to 50 at% scandium, the sputtering target having an oxygen content of less than or equal to 2000 ppm and the sputtering target having from 60 to 75% of an Al3Sc phase, from 15 to 25% of an AlSc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

[0158] Embodiment sixty-seven is the sputtering target of embodiment sixty-six, wherein the sputtering target contains from 12.5 at% to 45 at% scandium.

[0159] Embodiment sixty-eight is the sputtering target of embodiment sixty-six, wherein the sputtering target contains from 25 at% to 40 at% scandium.

[0160] Embodiment sixty-nine is the sputtering target of embodiment sixty-six, wherein the sputtering target has from 62 to 73% of an Al3Sc phase.

[0161] Embodiment seventy is the sputtering target of embodiment sixty-six, wherein the sputtering target has from 17 to 23% of an AISc phase.

[0162] Embodiment seventy-one is the sputtering target of embodiment sixty-six, wherein the sputtering target has from 7 to 12% of an AL phase.

[0163] Embodiment seventy-two is the sputtering target of embodiment sixty-six, wherein the sputtering target has from 0.5 to 3.5% of an AL2Sc phase.

[0164] Embodiment seventy-three is the sputtering target of embodiment sixty-six, wherein the sputtering target is less susceptible to cracking.Experimental methods

[0165] Some details regarding exemplary experimental methods are provided herein. The provision of these example is not intended to be (and is not) limiting.

[0166] Rockwell hardness is measured accordingto ASTM E18-17e1 .

[0167] Densities of samples is measured by hydrostatic weighing in distilled water using an analytical balance. Density accuracy is + / - 0.02g / cc.

[0168] Phase analysis and microstructural characterization may be determined via X-ray diffraction (XRD) using Cu-Ka radiation (A =0.15406nm) in the 29 range of 25-75°. An angular step size of 0.02° and counting time of 11 s / step may be used.EXAMPLESExample 1

[0169] 25 wt% of aluminum powder and 75 wt% of an aluminum scandium powder containing35 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 2 hours to form a sputtering target. The aluminum powder was prepared by gas atomization (GA). The aluminum powder was screened to 325 mesh (44 microns). The aluminum scandium powder was processed into irregular (non-spherical) particles by manual crushing without agglomeration. The aluminum scandium powder was screened to 100 mesh (149 microns). The sputtering target after consolidation contained 25 at% scandium. As shown in FIG. 1 , the phase structure contains Al phase (white) and elongated particles. The sputtering target was close to full dense having a density of 2.834 g / cc and a density % of 97.1 %. The density % is based on the mix rule density, assuming no reaction between the aluminum powder and the aluminum scandium powder. The hardness of the sputtering target was measured using Rockwell Hardness B and was 94-96 HRB.Example 2

[0170] 40 wt% of aluminum powder and 60 wt% of an aluminum scandium powder containing35 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The aluminum powder was prepared in the same manner as Example 1 . The aluminum scandium powder was processed into irregular (non- spherical) particles by manual crushing. The sputtering target after consolidation contained 19.2 at% scandium. As shown in FIG. 2, the particle boundaries are not visible. An Al phase (white) is still shown in FIG. 2. The majority of Al2Sc is transformed to Al3Sc via the reaction: Al + Al2Sc -> Al3Sc, which is confirmed by XRD and SEM / EDS. The sputtering target was full dense having a density of 2.923 g / cc and a density % of 101 .8%. The irregular and big particles are beneficial for decreased oxygen pick-up and work when there is enough amount of Al powder present at consolidation. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 78-80 HRB.Example 3

[0171] 40 wt% of aluminum powder and 60 wt% of an aluminum scandium powder containing35 at% scandium were consolidated under a hot press at 510°C and 193 MPa for 3 hours to form a sputtering target. The aluminum powder was prepared in the same manner as Example 1 . A high energy ball milling was used to obtain the aluminum scandium powder having an average diameter of 14 microns. High energy ball millingwas performed using a SPEX 8000M M ixe r / M ill for approximately 300 minutes at room temperature with grinding media of hardened steel. The sputtering target after consolidation contained 19.2 at% scandium. As shown in FIG. 3, the phase structure contains Al phase (white) and pores are present. The sputtering target has a density of 2.730 g / cc and a density % of 95.0%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 80-82 HRB.Example 4

[0172] The compact of Example 3 was further consolidated under neutral sinter without pressure at 600°C for 3 hours to form a sputtering target. The sputtering target after consolidation contained 19.2 at% scandium. As shown in FIG. 4, the phase structure contains a decreased amount of the Al phase (white) and concentrated pores. The sputtering target has a density of 2.75 g / cc and a density of 95.7%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 74-75 HRB.Example 5

[0173] The compact of Example 3 was further consolidated under neutral sinter without pressure at 800°C for 2 hours to form a sputtering target. The sputtering target after consolidation contained 19.2 at% scandium. As shown in FIG. 5, the phase structure contains a decreased amount of the Al phase and increased the pores. The sputtering target has a density of 2.80 g / cc and a density % of 97.5%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was decreased further to 52-59 HRB.Example 6

[0174] 40 wt% of aluminum powder and 60 wt% of an aluminum scandium powder containing35 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The aluminum powder was prepared in the same manner as Example 1 . A high energy ball milling was used to obtain the aluminum scandium powder having an average diameter of 6 microns. High energy ball milling was performed using dry grind Attritors for approximately 1200 minutes at room temperature with grinding media of hardened steel. The sputtering target after consolidation contained 19.2 at% scandium. As shown in FIG. 6A-6C, the phase structure contains Al phase and is fully dense. The sputtering target has a density of 2.86 g / cc and a density % of 99.6%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 88-89 HRB.

[0175] The hot press temperature can be used to manipulate phase components and adjust the phase ratio. As shown in FIG. 7, the as milled aluminum scandium powder containing35 at% scandium has almost single Al2Sc phase. The starting Al powder ratio is 40%, as the sintering temperature is increased to 510°C the Al ratio decreases to 26.8% due to a reaction between Al and Al2Sc phases forming a new phase of Al3Sc and at 600°C, the Al phase ratio is decreased to 21 .4% and Al2Sc phase disappeared. Beneficially, the Al phase is still present at the higher temperatures, while the Al2Sc phase is reduced.Example 7

[0176] 60 wt% of a first aluminum scandium powder containing 5 at% scandium and 40 wt% of a second aluminum scandium powder containing 50 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The first aluminum scandium powder containing 5 at% scandium was manufactured via centrifugal Helium atomization. The aluminum scandium powder containing 5 at% scandium was screened to 100 mesh (149 microns). The second aluminum scandium powder containing 50 at% scandium was also manufactured via centrifugal Helium atomization. The first and second aluminum scandium powder were spherical particles having an average diameter of 149 microns and 44 microns,respectively. The sputtering target after consolidation contained 20.5 at% scandium. As shown in FIG. 8, the Al phase (darker regions) diffused out and had no pores. The sputtering target in FIG. 8 also contained Al3Sc phase (lighter regions), but no intermediate Al2Sc phase and no original AISc phases. The sputtering target has a density of 100.3%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 93-96 HRB. The target produced by this method was more ductile and had a low hardness than a casted sputtering target.Example 8

[0177] 52 wt% of an aluminum powder and 48 wt% of an aluminum scandium powder containing50 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The aluminum powder was prepared in the same manner as Example 1 . The aluminum scandium powder containing50 at% scandium was manufactured via centrifugal Helium atomization. The aluminum scandium powder were spherical particles having an average diameter of 44 microns. The sputtering target after consolidation contained 20.5 at% scandium. As shown in FIG. 9, the Al phase (black regions) is visible with the Al3Sc phase (light regions). AISc is dissolved to form Al3Sc and there is no Al2Sc phase observed. The sputtering target has a density of 100.5%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 97-99 HRB.Example 9

[0178] 35 wt% of a first aluminum scandium powder containing 5 at% scandium and 65 wt% of a second aluminum scandium powder containing 30 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The aluminum scandium powder containing 5 at% scandium was prepared in the same manner as Example 1 . The second aluminum scandium powder containing 50 at% scandium was manufactured via centrifugal Helium atomization. The second aluminum scandium powders were spherical particles having an average diameter (d50) of 90-100 microns. The sputtering target after consolidation contained 20.5 at% scandium. As shown in FIG. 10, the first aluminum scandium powder containing 5 at% scandium diffused topure Al phase. The sputtering target in FIG. 10 contained central and interparticle pores. As shown in FIG. 10, the Al phase (white regions) is visible with the Al3Sc phase (light regions), and remaining Al2Sc phase (gray regions) in the center of the original particles. The sputtering target has a density of 98.2%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 78-79 HRB.Example 10

[0179] 28 wt% of an aluminum powder and 72 wt% of an aluminum scandium powder containing30 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The aluminum powder was prepared in the same manner as Example 1 . The aluminum scandium powder containing30 at% scandium was manufactured via centrifugal Helium atomization. The aluminum scandium powder were spherical particles having an average diameter (d50) of 90-100 microns. The sputtering target after consolidation contained 20.5 at% scandium. As shown in FIG. 11 , the sputtering target contained central pores (intrinsically from GA powder) but without interparticle pores, indicating pure Al, as a first powder, is more effective for consolidation than aluminum scandium powder containing 5 at% scandium. As shown in FIG. 11 , the Al phase (dark regions) is visible with the Al3Sc phase (light regions), and remaining Al2Sc phase (gray regions) in the center of the original particles. The sputtering target has a density of 100.0%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 79-81 HRB.Example 11

[0180] 38 wt% of a first aluminum scandium powder containing 5 at%. scandium and 62 wt% of a second aluminum scandium powder containing 50 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The first aluminum scandium powder was prepared in the same manner as Example 1 . The second aluminum scandium powder containing 50 at% scandium was also manufactured via centrifugal Helium atomization. The second aluminum scandium powders were spherical particles having an average diameter 44 microns. The sputteringtarget after consolidation contained 30 at% scandium. As shown in FIG. 12, the sputtering target contained the Al (white), original AISc (dark brown) and predominately newly-formed Al3Sc phase (grey). The sputtering target has a density of 94.3%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 95-98 HRB.Example 12

[0181] The powders of Example 10 were used under a hot press at 600°C and 48.3 MPa for 3 hours followed by a second hot press at 800°C and 48.3 MPa for 3 hours to form a sputtering target. FIG. 13 shows regions of newly-formed Al2Sc (light gray). No Al phase is present, presumably due to a further reaction of Al+AlSc->Al2Sc. The sputtering target has a density of 98.4%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 105-107 HRB.Example 13

[0182] 28 wt% of an aluminum powder and 72 wt% of an aluminum scandium powder containing50 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours to form a sputtering target. The aluminum powder was prepared in the same manner as Example 1 . The aluminum scandium powder containing50 at% scandium was manufactured via centrifugal Helium atomization. The second aluminum scandium powders were spherical particles having an average diameter of 44 microns. The sputtering target after consolidation contained 30 at% scandium. As shown in FIG. 14, the sputtering target contained central and interparticle pores. The phases in this sputtering target at Al phase (white 10%), original AISc (dark 20%), newly formed Al3Sc (light 65%) and Al2Sc (intermediate gray between AISc and Al3Sc, less than 5%). The sputtering target has a density of 96.7%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 98-99 HRB.Example 14

[0183] The powders of Example 13 were used under a hot press at 600°C and 48.3 MPa for 3 hours followed an annealing step at 950°C for 2 hours without pressure (or down force) and then a second hot press at 950°C and 48.3 MPa for 3 hours to form a sputtering target.The sputtering target after consolidation contained 30 at% scandium. FIGS. 15A and 15B shows regions of Al2Sc (light grey) and Al3Sc (dark). As shown in this example there is no Al phase and no AISc phase. The sputtering target has a density of 100.0%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness C and was 28-30 HRC. The ratio of Al3Sc / Al2Sc forms a sputtering target that is less brittle than a casted sputtering target.Example 15

[0184] 15 wt% of an aluminum powder and 80 wt% of an aluminum scandium powder containing50 at% scandium were consolidated under a hot press at 600°C and 193 MPa for 3 hours followed by hot press at 900°C and 58.6 MPa for 2 hours to form a sputtering target. The aluminum powder was prepared in the same manner as Example 1 . The aluminum scandium powder containing 50 at% scandium was manufactured via centrifugal Helium atomization. The aluminum scandium powders were spherical particles having an average diameter 44 microns. The sputtering target after consolidation contained 40 at% scandium. As shown in FIGS. 16A-16C shows micros through thickness (16A is the top, 16B in the middle, 16C the bottom) with fine pores at less than 10 microns. The sputtering target do not contain Al phase. The sputtering target has a density of 98.6%. The density % is based on the mix rule density. The hardness of the sputtering target was measured using Rockwell Hardness B and was 112-114 HRB. The ductile was improved over a directly casted 40 at% Sc.

[0185] While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference. In addition, it should be understood that aspects of the invention and portions of various embodiments and various features recited below and / or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will beappreciated by one of skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit.

Claims

We Claim:1 . A process for producing a sputtering target, the process comprising: providing a first powder having at least 90 wt% or more of an aluminum powder that contains from 0 to 10 at% scandium; providing a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium; and consolidating the first powder and the second powder to form the sputtering target.

2. The process of claim 1 , wherein 5 wt% to 95 wt% of the first powder is consolidated with 5 wt% to 95% of the second powder.

3. The process of any one of claims 1 or 2, wherein 5 wt% to 50 wt% of the first powder is consolidated with 50 wt% to 95% of the second powder.

4. The process of any one of claims 1-3, wherein 50 wt% to 95 wt% of the first powder is consolidated with 5 wt% to 50% of the second powder.

5. The process of any one of claims 1 -4, wherein the first powder has an average particle size (d50) ranging from 2 microns to 300 microns, preferably from 50 microns to 150 microns.

6. The process of any one of claims 1 -5, wherein the second powder has an average particle size (d50) ranging from 1 micron to 200 microns, preferably from 20 microns to 100 microns.

7. The process of any one of claims 1 -6, wherein the second powder has an Al3Sc / (Al3Sc+Al2Sc) ratio of greater than or equal to 0.5.

8. The process of any one of claims 1 -7, wherein the first powder or the second powder comprises less than or equal to 1000 ppm oxygen.

9. The process of any one of claims 1 -8, wherein the second powder comprises less than or equal to 1000 ppm metallic aluminum.

10. The process of any one of claims 1 -9, wherein the sputtering target has from 60 to 75% of an Al3Sc phase, from 15 to 25% of an AISc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

11. The process of any one of claims 1 -10, wherein the first powder is provided by heating a first metal source comprising from 0 to 10 at% scandium and contacting the heated first metal source with an atomization gas to form a first powder.

12. The process of any one of claims 1-11 , wherein the second powder is provided by heating a second metal source comprising from 25 at% to 80 at% scandium and contacting the heated second metal source with an atomization gas to form a second powder.

13. The process of any one of claims 1-11 , wherein the second powder is provided by contacting a second metal source with a grinding media to form a second powder having at least 90 wt% or more of an aluminum scandium powder that contains from 25 at% to 80 at% scandium.1 . The process of any one claims 1 -13, wherein the consolidating includes hot pressing, hot isostatic pressing, or spark plasma sintering.

15. A sputtering target produced by the process of any one of claims 1 -14, the sputtering target comprising an alloy of aluminum and scandium and containingfrom 10 at% to 50 at% scandium, the sputtering target having an oxygen content of less than or equal to 2000 ppm and the sputtering target having from 60 to 75% of an Al3Sc phase, from15 to 25% of an AISc phase, from 5 to 15% of an Al phase, and less than or equal to 5% of an Al2Sc phase, based on the total phases of the sputtering target.

Images