Aluminum-scandium composite, aluminum-scandium composite sputtering target and method for producing same

Abstract

To provide an Al-Sc alloy sputtering target that improves uniformity of stoichiometry and minimizes porosity, and to provide a method for making the same.SOLUTION: An Al-Sc alloy sputtering target. The target comprising from 1.0 at% to 65 at% scandium and from 35 at% to 99 at% aluminum and having a microstructure including a first aluminum matrix phase and a second phase dispersed uniformly therethrough. The second phase comprises one or more compounds corresponding to the formula ScxAly, where x is from 1 to 2 and y is from 0 to 3.SELECTED DRAWING: None

Description

[Technical Field]

[0001] cross reference

[0001] This application is related to and claims priority to U.S. Provisional Application No. 63 / 035,320, filed June 5, 2020, the entire contents of which are incorporated herein by reference.

[0002] This disclosure relates to alloys containing aluminum and scandium (Al-Sc alloys), and more particularly to the use of such Al-Sc alloys, and to articles and sputtering targets made from Al-Sc alloys. [Background technology]

[0003]

[0003] Aluminum scandium nitride (Al x Sc 1-x N) has gained interest for producing thin-film piezoelectric materials for a variety of applications. Traditional methods for producing these piezoelectric thin films utilize reactive sputter deposition. A sputtering target, usually a metal or metal alloy, is composed of the material to be sputtered. The sputtering target and substrate are placed in close proximity to each other in a chamber, and the target is bombarded with charged particles or ions. The high-energy ions dislodge portions of the sputtering target and redeposit them on the substrate. Sputtering is advantageous because it allows control over the film composition, allows for control over residual stress in the film, allows for high film deposition rates, and allows for easily controlled heating of the substrate. The use of this process in thin-film production has a well-established history.

[0004]

[0004] The properties of the resulting thin films are highly dependent on the uniform deposition of the Al-Sc alloy. This places considerable demands on the sputtering target and alloy properties. The piezoelectric response of the thin films is highly dependent on the scandium content of the film, so the overall stoichiometry and microdistribution of scandium in the sputtering target are important.

[0005]

[0005] In view of known alloys and sputtering targets, there is a need for alloys and sputtering targets that improve stoichiometric uniformity and minimize porosity. There is also a need for a microstructure that reduces target defects due to cracking and contamination from particle emission during sputtering (not individual atoms / ions, but particles that are ejected from the surface of the sputtering target and land on the wafer, often referred to as particulation). These features can result in sputtering targets with better performance and lifetime, leading to higher wafer yields and lower cost of ownership. Summary of the Invention

[0006] In one embodiment, the present disclosure provides an Al-Sc composite or sputtering target comprising 1.0 atomic % to 65 atomic % scandium and 35 atomic % to 99 atomic % aluminum, having a microstructure comprising a first phase (5 vol % to 99 vol %, e.g., 20 vol % to 99 vol %) and a second phase (1 vol % to 80 vol %) dispersed throughout the first phase, the second phase having the formula Al x Sc y where x is 0 to 3 and y is 1 to 2. The second phase may include ScAl3, ScAl2, ScAl, Sc2Al, or Sc, or a combination thereof, or may include ScAl2, ScAl, Sc2Al, or Sc, or a combination thereof. The second phase may include greater than 25 atomic % scandium and / or greater than 1 mole % Al2Sc, AlSc, AlSc2, or Sc , or a combination thereof, and / or less than 85 mol% aluminum, and / or 1.0 mol% to 70 mol% scandium nitride. The concentration of scandium in the second phase may exceed that predicted from an aluminum-scandium equilibrium phase diagram, for example, by at least 1%. The composite or sputtering target may further contain less than 1000 ppm, preferably less than 400 ppm, or more preferably less than 100 ppm oxygen. The grains of the first aluminum matrix phase may be characterized by a (110) crystallographic orientation or a random crystallographic orientation. The second phase may be characterized by a grain size ranging from 0.5 microns to 500 microns. The microstructure is substantially free of microcracks and fissures and / or oxide inclusions. The uniformity of scandium across the surface of the sputtering target may vary by less than ±0.5 atomic % scandium across the radius of the surface. The sputtering target may have a central axis through the thickness of the sputtering target and a diameter intersecting the central axis, and the uniformity of scandium across the central axis and diameter varies by less than ±0.5% by weight of scandium. The diameter may be greater than 300 mm.

[0007] In some embodiments, the present disclosure provides a method for preparing a non-equilibrium complex, comprising: x Sc y wherein x is 0 to 3 and y is 1 to 2; mixing the powder with a first phase containing aluminum to form a composite precursor; applying at least one of heat and pressure to the composite precursor to solidify the material; and cooling the solidified composite precursor to form a non-equilibrium composite.

[0008] A further 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. [Brief explanation of the drawings]

[0009] [Figure 1]

[0009] Phase diagram for aluminum and scandium. The y-axis is temperature (°C), ranging from 0°C to 1600°C in 200°C intervals. Also on the y-axis is a label indicating the melting point of aluminum, 660°C. [Figure 2]

[0010] FIG. 1 is a schematic cross-sectional view showing a conventional aluminum matrix. [Figure 3A]

[0011] FIG. 1 is a schematic cross-sectional view illustrating an exemplary microstructure of an Al—Sc alloy having a second phase. [Figure 3B]

[0012] FIG. 2 is a schematic cross-sectional view illustrating an exemplary microstructure of an Al—Sc alloy having a first and second phase. [Figure 4]

[0013] Figure 4A shows the microstructure of an Al-Sc alloy (multiple phases are shown). Figure 4B shows the microstructure of an Al-Sc alloy (multiple phases are shown). Figure 4C shows the microstructure of an Al-Sc alloy (multiple phases are shown). Figure 4D shows the microstructure of an Al-Sc alloy (multiple phases are shown). Figure 4E shows the microstructure of an Al-Sc alloy (multiple phases are shown). [Figure 5]

[0014] Figure 5A is a SEM image showing the microstructure of an Al-Sc alloy (displaying element distribution), Figure 5B is a SEM image showing the microstructure of an Al-Sc alloy (displaying element distribution), and Figure 5C is a SEM image showing the microstructure of an Al-Sc alloy (displaying element distribution). [Figure 6]

[0015] FIG. 1 is a collection of X-ray diffraction plots showing the metallic content of each component of a conventional Al—Sc alloy and an Al—Sc alloy according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0016] As previously mentioned, aluminum-scandium alloys produced using many conventional methods do not meet the demands for uniform stoichiometry, minimal porosity, and defect-free microstructures. As a result, films and substrates formed therefrom suffer from inconsistent properties. The alloys have poor thin film uniformity. Additionally, targets containing the alloys have poor physical / mechanical performance, such as defects that cause cracks that can lead to arcing or particulates during sputtering, resulting in yield loss and reduced target life. The industry needs targets that are defect-free, prevent target cracking, exhibit reduced particle emissions during sputtering, and have extended target life.

[0011] Aluminum-Scandium Composite

[0017] Disclosed herein are non-equilibrium composites containing a ductile first phase and a brittle second phase, for use as, for example, sputtering targets. The specific second phase, e.g., (brittle) intermetallic Al, present (in a specific amount) in the non-equilibrium composite is disclosed. x Sc y The use of Al phases maximizes the amount of ductile aluminum phase and reduces the amount of brittle intermetallic Al phase while maintaining the overall composition ratio in the composite. x Sc y It has been found that this results in a microstructure that minimizes the amount of intermetallic Al phases that have higher scandium contents and / or lower amounts of aluminum (outside the range of amounts predicted by the aluminum-scandium equilibrium phase diagram). This results in a desirable combination of the aforementioned characteristics, such as uniformity in the bulk composition of the aluminum-scandium alloy, and a microstructure that is free of defects and porosity, as well as prevention of target cracking and reduced casting defects and particle shedding. x Sc y The desired increase in ductile phase content is achieved by using less intermetallic Al phase. x Sc y phase is used, a greater amount of the ductile aluminum phase is available, providing the benefits previously mentioned.

[0012]

[0018] As previously mentioned, the addition of a metastable ductile phase, such as "free aluminum," to the microstructure can reduce grain size and improve overall target performance. The added ductility provided by the ductile phase also facilitates thermomechanical processing of these materials. This allows for the repair of casting defects such as solidification pores and non-uniform microstructures. Arcing is also reduced, improving consistency of sputtering performance throughout the target's life. Thin films produced using the sputtering targets disclosed herein also advantageously exhibit reduced grain size during sputtering. Particles that are undesirably expelled from the particle surface are considered contaminants because they affect and reduce overall device yield. In some embodiments, the (uniform) macroscopic distribution of the brittle second phase results in composites that have surprisingly been found to have a more uniform composition, and therefore, result in sputtering targets that produce higher quality thin films. Additionally, the composites formed by the disclosed methods can advantageously produce larger diameter sputtering targets that, in some cases, are prone to cracking when produced by conventional methods.

[0013]

[0019] Previously, it has been difficult to achieve the desired amount (of ductile aluminum phase), if any, in higher scandium-containing alloys because conventional manufacturing (casting) methods yielded equilibrium microstructures with lower aluminum contents and phase volume ratios predicted by the aluminum-scandium equilibrium phase diagram. By utilizing the non-equilibrium phase distributions referred to herein, however, composites produced by the methods disclosed herein achieve the desired amount of ductile aluminum phase throughout the composition.

[0014]

[0020] By carefully designing the phases present in the composite target, compared to conventional balanced alloys that have little, if any, free aluminum (alloys below 25% Sc) or no balance aluminum (alloys with Sc contents equal to or greater than 25% Sc), the amount of ductile phase present can be beneficially increased, thereby increasing the ductility and strength of the material, improving chemical uniformity, and reducing the amount of particulate matter that occurs during sputtering.

[0015] Macroscopic structure

[0021] The present disclosure relates to composites comprising aluminum and scandium (Al-Sc composites). The Al-Sc composites can be used to manufacture articles, such as sputtering targets, that have, among other advantages, high compositional uniformity with a uniform distribution of a second phase. In some embodiments, the Al-Sc composite contains 1.0 atomic % to 65 atomic % scandium and 35 atomic % to 99 atomic % aluminum (optionally with other elements). Further compositional details are provided below.

[0016]

[0022] Overall, the disclosed composites in some embodiments include 1.0 atomic % to 65 atomic % scandium, e.g., 5 atomic % to 55 atomic %, 5 atomic % to 45 atomic %, 10 atomic % to 50 atomic %, 15 atomic % to 45 atomic %, 20 atomic % to 40 atomic %, 1.0 atomic % to 5 atomic %, 5 atomic % to 10 atomic %, 10 atomic % to 15 atomic %, 15 atomic % to 20 atomic %, 20 atomic % to 25 atomic %, 25 atomic % to 30 atomic %, 30 atomic % to 35 atomic %, 35 atomic % to 40 atomic %, 40 atomic % to 45 atomic %, 45 atomic % to 50 atomic %, 50 atomic % to 55 atomic %, 55 atomic % to 60 atomic %, or 60 atomic % to 65 atomic % scandium. [Experimental data, if available, will be verified to be consistent with the Examples.]

[0023] In terms of lower limits, the composite may contain more than 1.0 atomic %, e.g., more than 5 atomic %, more than 10 atomic %, more than 15 atomic %, more than 20 atomic %, more than 25 atomic %, more than 30 atomic %, more than 35 atomic %, more than 40 atomic %, more than 45 atomic %, more than 50 atomic %, more than 55 atomic %, or more than 60 atomic % scandium. In terms of upper limits, the composite may contain less than 65 atomic %, e.g., less than 60 atomic %, less than 55 atomic %, less than 50 atomic %, less than 45 atomic %, less than 40 atomic %, less than 35 atomic %, less than 30 atomic %, less than 25 atomic %, less than 20 atomic %, less than 15 atomic %, less than 10 atomic %, or less than 5 atomic % scandium.

[0017]

[0024] As used herein, the limitations "greater than" and "less than" are inclusive. In other words, "greater than" and "less than" may be interpreted as "greater than or equal to" and "less than or equal to." It is understood that this language may be later modified in the claims to include "or equal to." For example, "greater than 4.0" may be interpreted as "greater than or equal to 4.0" and later modified in the claims to "greater than or equal to 4.0."

[0018]

[0025] In some embodiments, the composite comprises 35 atomic % to 99 atomic %, e.g., 40 atomic % to 95 atomic %, 45 atomic % to 90 atomic %, 50 atomic % to 80 atomic %, 55 atomic % to 75 atomic %, 60 atomic % to 75 atomic %, 62 atomic % to 72 atomic %, 35 atomic % to 40 atomic %, 40 atomic % to 50 atomic %, 50 atomic % to 55 atomic %, 55 atomic % to 60 atomic %, 60 atomic % to 65 atomic %, 65 atomic % to 70 atomic %, 70 atomic % to 75 atomic %, 75 atomic % to 80 atomic %, 80 atomic % to 85 atomic %, 85 atomic % to 90 atomic %, 90 atomic % to 95 atomic %, or 95 atomic % to 99 atomic % aluminum. These amounts account for the aluminum present in the first phase (as free aluminum) and the aluminum present as a component in the intermetallic second phase.

[0019]

[0026] At the lower end, the composite may contain more than 35 atomic %, e.g., more than 40 atomic %, more than 45 atomic %, more than 50 atomic %, more than 55 atomic %, more than 60 atomic %, more than 65 atomic %, more than 70 atomic %, more than 75 atomic %, more than 80 atomic %, more than 85 atomic %, more than 90 atomic %, or more than 95 atomic % aluminum. At the upper end, the composite may contain less than 99 atomic %, e.g., less than 95 atomic %, less than 90 atomic %, less than 85 atomic %, less than 80 atomic %, less than 75 atomic %, less than 70 atomic %, less than 65 atomic %, less than 60 atomic %, less than 55 atomic %, less than 50 atomic %, less than 45 atomic %, or less than 40 atomic % aluminum.

[0020]

[0027] In some embodiments, the composite comprises 1.0 mol% to 70 mol%, e.g., 1 mol% to 5 mol%, 5 mol% to 10 mol%, 10 mol% to 15 mol%, 20 mol% to 25 mol%, 25 mol% to 30 mol%, 30 mol% to 35 mol%, 35 mol% to 40 mol%, 40 mol% to 45 mol%, 45 mol% to 50 mol%, 50 mol% to 55 mol%, 55 mol% to 60 mol%, 60 mol% to 65 mol%, or 65 mol% to 70 mol% scandium nitride. At the lower end, the alloy may contain more than 1 mol%, e.g., more than 5 mol%, more than 10 mol%, more than 15 mol%, more than 20 mol%, more than 25 mol%, more than 30 mol%, more than 35 mol%, more than 40 mol%, more than 45 mol%, more than 50 mol%, more than 55 mol%, more than 60 mol%, or more than 65 mol% scandium nitride. At the upper end, the alloy may contain less than 70 mol%, e.g., less than 65 mol%, less than 60 mol%, less than 55 mol%, less than 50 mol%, less than 45 mol%, less than 40 mol%, less than 35 mol%, less than 30 mol%, less than 25 mol%, less than 20 mol%, less than 15 mol%, less than 10 mol%, or less than 5 mol% scandium nitride.

[0021]

[0028] Nitride powders are useful in controlling oxygen absorption and can passivate powder components and stabilize them with molten aluminum during processing.

[0022]

[0029] In some cases, the composite is highly pure and contains as few impurities as possible. For example, oxygen is extremely detrimental to the properties of piezoelectric films, both by selectively bonding to the substrate and by stabilizing other non-piezoelectric phases. Therefore, the composite or sputtering target should contain as little oxygen as possible. In some embodiments, the composite contains less than 1500 ppm of oxygen, e.g., less than 1000 ppm, less than 900 ppm, less than 800 ppm, less than 700 ppm, less than 600 ppm, less than 500 ppm, less than 400 ppm, less than 300 ppm, less than 200 ppm, or less than 100 ppm. The presence of transition metal elements, such as iron, should also be minimized.

[0023]

[0030] In some embodiments, the uniformity of scandium across the surface of the composite, e.g., a sputtering target formed from the composite, varies by less than ±0.5 atomic % of scandium across the surface, e.g., less than ±0.4 atomic %, less than ±0.3 atomic %, less than ±0.2 atomic %, less than ±0.1 atomic %, or less than ±0.05 atomic % of scandium. In some embodiments, the uniformity of scandium across the central axis and diameter of a sputtering target formed from the composite and having a central axis and a diameter intersecting the central axis through the thickness of the sputtering target varies by less than ±0.5 atomic % of scandium, e.g., less than ±0.4 atomic %, less than ±0.3 atomic %, less than ±0.2 atomic %, less than ±0.1 atomic %, or less than ±0.05 atomic % of scandium.

[0024]

[0031] Sputtering targets made from the composite can be used to deposit thin films on substrates. The piezoelectric properties of individual devices on a substrate depend heavily on the local stoichiometry of the films contained within each device. Therefore, the distribution of scandium in an Al-Sc sputtering target should be as uniform as possible, both across the surface (e.g., on the surface) and through the thickness of the sputtering target. If the amount of scandium sputtered from the target fluctuates over the life of the target, the piezoelectric properties of the deposited film will change over the life of the target, resulting in inconsistent device performance and loss of product yield. Chemical uniformity across the surface and through the thickness is essential. The properties and characteristics of the composite are described below.

[0025] Microstructure

[0032] In some embodiments, the composite comprises a ductile first phase and a matrix The composite may include a brittle second phase dispersed throughout the composite, the second phase including aluminum and scandium. The scandium present throughout the composite is optionally provided by the second phase. Optionally, the second phase has the formula Al x Sc y where x is 0 to 3 and y is 1 to 2. The second phase may include AlSc, AlSc, AlSc, ScAl, or Sc, or a combination thereof.

[0026]

[0033] In some embodiments, the composite comprises 5% to 99% by volume, e.g., 20% to 99% by volume, of the first phase (free aluminum) and 1% to 80% by volume of the second phase, based on the total volume of the composite. For example, the composite may comprise 5% to 95% by volume, e.g., 40% to 90% by volume, 5% to 50% by volume, 5% to 35% by volume, 5% to 25% by volume, 10% to 50% by volume, 10% to 40% by volume, 10% to 25% by volume, 7% to 50% by volume, 7% to 40% by volume, 7% to 30% by volume, 7% to 25% by volume, 45% to 85% by volume, 50% to 80% by volume, 55% to 75% by volume, or 60% to 70% by volume of the first phase. At the lower end, the composite may comprise more than 5 vol%, e.g., more than 7 vol%, more than 10 vol%, more than 12 vol%, more than 15 vol%, more than 17 vol%, more than 20 vol%, more than 40 vol%, more than 45 vol%, more than 50 vol%, more than 55 vol%, more than 60 vol%, more than 65 vol%, or more than 70 vol% of the first phase. At the upper end, the composite may comprise less than 99 vol%, e.g., less than 95 vol%, less than 90 vol%, less than 85 vol%, less than 80 vol%, less than 75 vol%, less than 70 vol%, less than 60 vol%, less than 50 vol%, less than 45 vol%, less than 40 vol%, less than 35 vol%, less than 30 vol%, less than 25 vol%, less than 20 vol%, less than 15 vol%, or less than 10 vol% of the first phase.

[0027]

[0034] The amount of first and second phases present can be quantitatively measured by optical and SEM / EDS microscopy, EBSD, or other known techniques.

[0028]

[0035] Optionally, the first phase may contain small amounts of scandium, for example, less than 1 wt.%, less than 0.5 wt.%, less than 0.2 wt.%, or less than 0.1 wt.%.

[0029]

[0036] In some embodiments, the composite comprises 1% to 80% by volume of the second phase, e.g., 5% to 75% by volume, 10% to 70% by volume, 15% to 65% by volume, 20% to 60% by volume, 25% to 55% by volume, or 30% to 50% by volume. At the lower end, the composite may comprise more than 20% by volume, e.g., more than 1%, more than 5%, more than 10%, more than 15%, more than 20%, more than 25%, more than 30%, or more than 35% by volume of the second phase. At the upper end, the composite may comprise less than 80% by volume, e.g., less than 75%, less than 70%, less than 65%, less than 60%, less than 55%, or less than 50% by volume of the first phase. Because the scandium content of the disclosed second phases is higher than conventional alloys using equilibrium phase distributions, as determined by equilibrium phase diagrams, these amounts are typically lower than those used in conventional alloys. Thus, a lower overall scandium concentration can be achieved using a smaller amount of the second phase. Because a smaller amount of the second phase is used, a larger amount of the ductile aluminum phase can be advantageously utilized.

[0030]

[0037] Figure 1 is a phase diagram of aluminum and scandium. The x-axis shows the amount of scandium in atomic percent (at.%), with zero scandium and 100 at.% aluminum at the left end of the diagram. Examination of the Al-Sc phase diagram reveals that balanced alloys with 0 to 25 at.% scandium can contain the intermetallic Al3Sc phase in a metallic aluminum matrix. At higher scandium contents, the composite can contain Al3Sc, Al It may contain one or more intermetallic phases selected from 2Sc, AlSc, AlSc2, or it may contain scandium, or it may contain any combination of an intermetallic phase and scandium.

[0031]

[0038] The second phase in the composite comprises a large amount / high concentration of scandium, e.g., an amount / concentration of scandium outside of, e.g., greater than, an amount / concentration of scandium predicted by an aluminum-scandium equilibrium phase diagram. For example, the second phase can comprise greater than (or equal to), 25 atomic %, e.g., greater than 28 atomic %, greater than 30 atomic %, greater than 33 atomic %, greater than 35 atomic %, greater than 40 atomic %, greater than 45 atomic %, greater than 50 atomic %, greater than 55 atomic %, greater than 65 atomic %, greater than 66 atomic %, greater than 70 atomic %, greater than 75 atomic %, greater than 80 atomic %, greater than 85 atomic %, or greater than 90 atomic % scandium based on the total amount of the second phase.

[0032]

[0039] The second phase includes certain intermetallic phases, such as Al3Sc, Al2Sc, AlSc, and AlSc2, in amounts outside of the range of amounts / concentrations predicted, for example, by an aluminum-scandium equilibrium phase diagram. For example, the second phase may include these intermetallic phases in an amount greater than 5 mol%, e.g., greater than 10 mol%, greater than 15 mol%, greater than 20 mol%, greater than 25 mol%, greater than 30 mol%, greater than 35 mol%, greater than 40 mol%, greater than 45 mol%, greater than 50 mol%, greater than 55 mol%, greater than 60 mol%, or greater than 65 mol% of the total amount of the second phase. In terms of upper limits, the second phase can include these intermetallic phases in an amount of less than 95 mol%, e.g., less than 90 mol%, less than 85 mol%, less than 80 mol%, less than 75 mol%, less than 70 mol%, less than 65 mol%, less than 60 mol%, less than 60 mol%, less than 55 mol%, less than 50 mol%, less than 45 mol%, less than 40 mol%, less than 35 mol%, less than 30 mol%, or less than 25 mol%.

[0033]

[0040] In some embodiments, these amounts / concentrations are outside (eg, exceed) the range of amounts / concentrations predicted by the aluminum-scandium equilibrium phase diagram.

[0034]

[0041] In some embodiments, intermetallic phases having greater amounts / higher concentrations of scandium and / or lesser amounts of aluminum may be utilized. For example, the second phase may include AlSc, AlSc, AlSc, AlSc, or Sc, or combinations thereof, in an amount greater than 1 mol%, e.g., greater than 2 mol%, greater than 5 mol%, greater than 10 mol%, greater than 15 mol%, greater than 20 mol%, greater than 25 mol%, greater than 30 mol%, greater than 35 mol%, greater than 40 mol%, greater than 45 mol%, greater than 50 mol%, greater than 55 mol%, greater than 60 mol%, or greater than 65 mol%, based on the total number of moles of the second phase. In some embodiments, these amounts / concentrations are outside (e.g., exceed) the ranges of amounts / concentrations predicted by an aluminum-scandium equilibrium phase diagram. These ranges and limits are applicable to the intermetallic phases collectively and to each intermetallic phase individually.

[0035]

[0042] It has been found that some second phase components can be particularly brittle and detrimental to the composition as a whole. In some embodiments, the second phase includes a certain amount of an intermetallic phase, such as AlSc. For example, the second phase can include less than 60 mol%, e.g., less than 55 mol%, less than 50 mol%, less than 40 mol%, less than 30 mol%, less than 20 mol%, less than 10 mol%, or less than 5 mol% AlSc, based on the total number of moles of the second phase. In some embodiments, the second phase is free or substantially free of AlSc.

[0036]

[0043] The second phase, if present, contains small amounts / concentrations of aluminum, e.g., amounts / concentrations outside the range of amounts / concentrations predicted by the aluminum-scandium equilibrium phase diagram. The second phase may contain less than (or equal to) 75 atomic % aluminum, for example less than 70 atomic %, less than 66 atomic %, less than 65 atomic %, less than 60 atomic %, less than 55 atomic %, less than 50 atomic %, less than 45 atomic %, less than 40 atomic %, or less than 35 atomic % aluminum, relative to the total amount of the second phase.

[0037]

[0044] In some cases, the amount of scandium in the second phase is greater than that predicted from an aluminum-scandium equilibrium phase diagram, e.g., at least 1% more, at least 2% more, at least 5% more, at least 10% more, at least 15% more, at least 20% more, at least 25% more, at least 35% more, at least 50% more, at least 75% more, or at least 100% more.

[0038]

[0045] 3A and 3B represent schematic cross-sectional views of Al—Sc alloy microstructures, and FIG. 2 represents a conventional aluminum alloy 100 having an aluminum-rich metal matrix 120 without the presence of a second phase. FIG. 3A represents an Al—Sc alloy 200 according to the present disclosure, which may include a second phase 150 uniformly dispersed throughout the aluminum matrix 120. In some cases, said second phase may be dispersed a spatial distance d1 apart, which may include a range of values.

[0039]

[0046] The second phase may, in some embodiments, comprise multiple discrete phases, e.g., a second phase, a third phase, and a fourth phase. Phases higher than the second phase, e.g., a third phase, a fourth phase, etc., are intended to have the same description and properties as those set forth above for the second phase. For example, the third phase may have a high scandium content, e.g., outside of the range of amounts expected from an aluminum-scandium equilibrium phase diagram.

[0040]

[0047] For example, Figure 3B shows another Al-Sc composite 300 according to the present disclosure including a second phase 150 and a third phase 160 uniformly dispersed throughout a first phase 120. Phases 150 and 160 can be as described herein. A composite according to the present disclosure, not shown, can include more than four phases, for example, five or six phases, each dispersed throughout the first phase.

[0041]

[0048] In some embodiments, the first phase grains and the second phase grains each have an average grain size that can be measured according to ASTM E112 (this year).

[0042]

[0049] In some embodiments, the first phase is characterized by having an average particle size ranging from 2 μm to 200 μm, e.g., from 10 μm to 150 μm, from 15 μm to 125 μm, from 20 μm to 100 μm, from 25 μm to 75 μm, from 2 μm to 40 μm, from 2 μm to 20 μm, from 4 μm to 12 μm, from 10 μm to 100 μm, from 20 μm to 80 μm, from 30 μm to 70 μm, or from 40 μm to 70 μm.

[0043]

[0050] At the lower end, the first phase may be characterized by an average particle size of greater than 2 μm, e.g., greater than 4 μm, greater than 10 μm, greater than 20 μm, greater than 25 μm, greater than 30 μm, greater than 40 μm, or greater than 50 μm. At the upper end, the first phase may be characterized by an average particle size of less than 200 μm, e.g., less than 150 μm, less than 125 μm, less than 100 μm, less than 80 μm, less than 75 μm, less than 70 μm, less than 40 μm, less than 20 μm, or less than 12 μm.

[0044]

[0051] In some embodiments, the grains of the first aluminum matrix phase are characterized as having a (110) crystallographic orientation. In other embodiments, the grains of the first aluminum matrix phase are characterized as having no preferred crystallographic orientation or as having a random structure. In some cases, the structure may be quantified by XRD peak height ratio, EBSD volume ratio, EBSD structure analysis MRD value, and / or XRD pole figure MRD value.

[0045]

[0052] In some embodiments, the first phase grains are characterized by having random crystallographic orientation.

[0046]

[0053] It may be desirable for the second phase to be as fine as possible, more particularly, to have an average particle size of less than 100 microns (μm). In some embodiments, the second phase is characterized by an average particle size ranging from 0.5 μm to 500 μm, e.g., from 1 μm to 450 μm, e.g., from 10 μm to 400 μm, from 50 μm to 400 μm, from 100 μm to 350 μm, or from 200 μm to 300 μm. At the lower end, the second phase is characterized by an average particle size greater than 0.5 μm, e.g., greater than 1 μm, greater than 10 μm, greater than 50 μm, greater than 100 μm, or greater than 200 μm. At the upper end, the second phase is characterized by an average particle size less than 500 μm, e.g., less than 400 μm, less than 350 μm, less than 300 μm, or less than 250 μm.

[0047]

[0054] In some cases, the microstructure of a sputtering target is uniform across the target's surface area (typically a disk 12.70 cm (5 inches) to 45.72 cm (18 inches) in diameter, or about 125 mm to about 450 mm) and throughout its entire thickness (typically approximately 0.635 cm (1 / 4 inch) or 0.635 cm (1 / 4 inch), or about 6 mm to about 7 mm). The dimensions of the microstructure in a sputtering target are also important. Defects such as microcracks and fissures, pores, refractory or dielectric inclusions, oxide inclusions, and large intermetallic phase grains should be avoided because they are usually accompanied by undesirable phenomena such as microarcing and particulation, and have a significant adverse effect on film properties.

[0048]

[0055] In some embodiments, the aluminum-scandium composite has a microstructure that is free or substantially free of microcracks and cracks, which can be measured using optical / SEM metallography.

[0049]

[0056] In some embodiments, the aluminum-scandium composite has a non-porous or substantially non-porous microstructure, with the porosity of the composite measured being less than 3%, e.g., less than 2%, less than 1%, less than 0.9%, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.3%, less than 0.2%, or less than 0.1%.

[0050]

[0057] In some embodiments, the aluminum-scandium alloy has a microstructure that is free or substantially free of oxide inclusions.

[0051]

[0058] Microscopy can be used to quantify the above measurements.

[0052]

[0059] In some embodiments, the aluminum-scandium composite sputtering target has a diameter or cross measurement of greater than 125 mm, e.g., greater than 150 mm, greater than 200 mm, greater than 300 mm, greater than 350 mm, or greater than 400 mm.

[0053]

[0060] The aluminum-scandium composite sputtering target can have a thickness, eg, height, ranging from 1 mm to 50 mm, eg, from 1 mm to 40 mm, from 2 mm to 35 mm, from 2 mm to 25 mm, from 3 mm to 15 mm, or from 5 mm to about 10 mm.

[0054] method

[0061] A method for producing a (non-equilibrium) aluminum-scandium complex as disclosed herein. In some embodiments, the method comprises: x Sc y(wherein x is 0 to 3 and y is 1 to 2), and mixing the powder with a first phase (powder) containing aluminum to form a composite precursor. The method may further include applying at least one of heat or pressure to the composite precursor to consolidate the materials, e.g., the first phase powder and the second phase powder. The method further includes cooling the consolidated composite precursor to form a non-equilibrium composite.

[0055]

[0062] In some cases, temperatures in the range of 300°C to 900°C, e.g., 350°C to 850°C, 400°C to 800°C, or 500°C to 700°C, are used. For the lower limit, temperatures above 300°C, e.g., above 350°C, above 400°C, or above 500°C, may be used. For the upper limit, temperatures below 900°C, e.g., below 850°C, below 800°C, or below 700°C, may be used.

[0056]

[0063] In some cases, pressures in the range of 3000 kPa to 11000 kPa, e.g., 4000 kPa to 10000 kPa, 5000 kPa to 9000 kPa, or 6000 kPa to 8000 kPa, are used. For lower limits, pressures greater than 3000 kPa, e.g., greater than 4000 kPa, greater than 5000 kPa, or greater than 6000 kPa, may be used. For upper limits, pressures less than 11000 kPa, e.g., less than 10000 kPa, less than 9000 kPa, or less than 8000 kPa, may be used.

[0057]

[0064] In some embodiments, e.g., when rapid cooling is performed, e.g., in a squeeze casting process, the cooling of the composite may occur at a rate of greater than 1°C / min, e.g., greater than 5°C / min, greater than 10°C / min, greater than 20°C / min, greater than 25°C / min, or greater than 35°C / min.

[0058]

[0065] In some cases, a cooling step is used to retain the amount of non-phase diagram intermetallic phase in the second phase in the matrix of the first phase without reverting to an equilibrium phase and / or amount. In some embodiments, a cooling step is used to maintain a non-equilibrium phase mixture without reverting to an equilibrium phase mixture.

[0059]

[0066] In some embodiments, the scandium-aluminum composites described herein can be formed through a casting process, preferably using aluminum (first phase) powder and intermetallic (second phase) powder. Melt processing, e.g., via a casting route, also produces composites with much lower oxygen contents than powder processing, e.g., less than 1000 ppm, less than 800 ppm, less than 600 ppm, less than 400 ppm, less than 300 ppm, less than 200 ppm, or less than 100 ppm. Thus, casting of aluminum-scandium alloys is suitable for producing the disclosed composites. In some cases, e.g., when using casting techniques, free aluminum is increased / maintained by maintaining the temperature below a certain level. Maintaining the temperature within these ranges and extremes advantageously avoids / minimizes the formation of unwanted metallic phase components.

[0060]

[0067] In a typical casting process, the composite components are melted together at high temperature in a crucible and then poured into a mold where the molten composite solidifies into an ingot. Solidification typically proceeds from the bottom and walls of the mold toward the center, so the outermost regions of the casting are expected to cool much faster than the central region.

[0061]

[0068] In some cases, rapid cooling rates in castings with high intermetallic loading can cause large internal stress buildup, potentially leading to cracks in the casting. Also, many casting composites have the potential to destroy the characteristic structure associated with the casting, resulting in a uniform microstructure throughout the thickness of the target. To achieve this, the castings are subjected to subsequent thermomechanical processing (e.g., plastic deformation and / or heat treatment). Brittle castings typically do not have much resistance to such thermomechanical processing steps. However, the disclosed composites, due to their composition, may be able to withstand this processing. [Example]

[0062] Example 1

[0069] To produce the composite sputtering target of Example 1, an intermetallic (second phase) Al containing a plurality of intermetallic aluminum-scandium phases was prepared. 47 Sc 53 Powders were prepared. AlSc and Sc were mixed in a Turbula® mixer for 10 minutes to form a precursor. The precursor was loaded into a 12.70 cm (5 inch) graphite mold and compacted by hot pressing. The compacted precursor was heated and compacted at 600°C and 1000 psi, respectively, for approximately 4 hours. The formed precursor was removed at room temperature and cooled. 200 grams of the cooled precursor was crushed with 50 grams of (free) aluminum powder to form a sputtering target composite precursor, which was further processed to produce a sputtering target composite. The total (free) aluminum content was approximately greater than 20 atomic %, and the total scandium content was approximately 40 atomic %. These percentages are outside the range of amounts predicted by the aluminum-scandium equilibrium phase diagram.

[0063] Comparative example A

[0070] A comparative intermetallic powder for Comparative Example A was prepared by alloying 145 grams of aluminum and 105 grams of scandium. These components were alloyed under vacuum at approximately 1450°C to form a precursor. The precursor was cast using a mold using a conventional casting process and then cooled to room temperature.

[0064]

[0071] The total aluminum and scandium contents of the alloy were consistent with those predicted from the aluminum-scandium equilibrium phase diagram.

[0065] [Table 1]

[0072] As shown in Table 1, the target of Example 1 exhibited a high (free) aluminum content and a low intermetallic phase, e.g., AlSc content. Due to the high free aluminum / low ScAl content, the sputtering target should exhibit excellent ductility.

[0066]

[0073] 4A-4E are exemplary diagrams showing the microstructure of an Al-Sc alloy (multiple phases are displayed). The circular dots indicate scandium-containing second intermetallic phases, such as ScAl3, ScAl2, ScAl, Sc2Al, Sc, or combinations thereof, while the remaining areas represent the (first) free aluminum phase. Diagrams are shown for scandium concentrations of 10, 15, 20, 25, and 30 atomic percent of the total composition.

[0067]

[0074] Figures 5A-5C are SEM images showing the microstructure of an Al-Sc alloy. Figure 5A shows a microstructure mapped by EDS (energy dispersive x-ray spectroscopy) to show aluminum content, e.g., free aluminum and / or aluminum-containing intermetallics (see speckled areas). Figure 5B shows a microstructure mapped by EDS to show scandium content, e.g., scandium-containing intermetallic phases (see shaded areas). Figure 5C shows a microstructure mapped by EDS to show free aluminum content. Areas showing both the presence of aluminum and scandium indicate intermetallic (second phase) content. The free aluminum content (first phase) is represented in Figure 5C by areas containing aluminum but not scandium (the presence of scandium is shown in Figure 5B) (see speckled areas in Figure 5C). The free aluminum (first phase) areas were analyzed and calculated to represent approximately 15% to 40% by volume of the total alloy.

[0068]

[0075] Figure 6 shows X-ray diffraction plots showing the metal content for each component of the comparative Al-Sc alloy and the examples. As shown in the top comparative plot, the peaks shown are those associated with intermetallic phases, e.g., AlSc and AlSc, and no peaks associated with free aluminum are shown. Meanwhile, the middle plot for the examples shows free aluminum peaks at approximately 38 and 45 degrees. These peaks indicate significant free aluminum content, which is advantageous. The bottom plot shows Top row and Including the peaks shown in the middle plot and intermetallic phases. Comparative Examples and Individual peaks for all components for the examples are shown. The peaks were analyzed and extrapolated to calculate volume percentages. The volume percentage of free aluminum (first phase) in the examples was calculated to be approximately 15% to 40% by volume of the total composition.

[0069] Embodiment

[0076] The following embodiments are possible: All combinations of features and embodiments are possible.

[0070]

[0077] Embodiment 1: An Al-Sc composite comprising 1.0 atomic % to 65 atomic % scandium and 35 atomic % to 99 atomic % aluminum, having a microstructure comprising a first phase and a second phase dispersed throughout the first phase, the second phase having the formula Al x Sc y wherein x is 0 to 3 and y is 1 to 2.

[0071]

[0078] Embodiment 2: An Al-Sc composite sputtering target comprising 1.0 atomic % to 65 atomic % scandium and 35 atomic % to 99 atomic % aluminum, having a microstructure comprising a first phase and a second phase dispersed throughout the first phase, the second phase having the formula Al x Sc y wherein x is 0 to 3, and y is 1 to 2.

[0072]

[0079] Embodiment 3: The embodiment of embodiment 1 or 2, wherein the second phase comprises ScAl3, ScAl2, ScAl, Sc2Al, or Sc, or a combination thereof.

[0073]

[0080] Embodiment 4: The embodiment of any of embodiments 1-3, wherein the second phase comprises ScAl2, ScAl, Sc2Al, or Sc, or a combination thereof.

[0074]

[0081] Embodiment 5: Any of embodiments 1-4, wherein the microstructure comprises 5 vol% to 99 vol%, e.g., 20 vol% to 99 vol%, of a first phase and 1 vol% to 80 vol% of a second phase, as determined by quantitative image analysis.

[0075]

[0082] Embodiment 6: The embodiment of any of embodiments 1-5, wherein the concentration of scandium in the second phase is higher than that predicted from the aluminum-scandium equilibrium phase diagram.

[0076]

[0083] Embodiment 7: The embodiment of any of embodiments 1-6, wherein the concentration of scandium in the second phase is at least 1% higher than the concentration predicted from the aluminum-scandium equilibrium phase diagram.

[0077]

[0084] Embodiment 8: The embodiment of any of embodiments 1-7, wherein the second phase comprises greater than 25 atomic % scandium.

[0078]

[0085] Embodiment 9: The embodiment of any of embodiments 1-8, wherein the second phase comprises greater than 1 mol % Al2Sc, AlSc, AlSc2, or Sc, or a combination thereof.

[0079]

[0086] Embodiment 10: The embodiment of any of embodiments 1-9, wherein the second phase comprises less than 85 mole % aluminum.

[0080]

[0087] Embodiment 11: The embodiment of any of embodiments 1-10, wherein the second phase further comprises 1.0 mol % to 70 mol % scandium nitride.

[0081]

[0088] Embodiment 12: Any of embodiments 1 to 11, wherein the grains of the first aluminum matrix phase have a crystallographic orientation of (110).

[0082]

[0089] Embodiment 13: The embodiment of any one of embodiments 1 to 12, wherein the grains of the first aluminum matrix phase have random crystal orientation.

[0083]

[0090] Embodiment 14: The embodiment of any of embodiments 1-13, wherein the second phase has a particle size ranging from 0.5 microns to 500 microns.

[0084]

[0091] Embodiment 15: The embodiment of any of embodiments 1-14, wherein the microstructure is substantially free of microcracks and fissures.

[0085]

[0092] Embodiment 16: The embodiment of any of embodiments 1-15, wherein the microstructure is substantially free of oxide inclusions.

[0086]

[0093] Embodiment 17: The embodiment of any of embodiments 1-16, wherein the composite or sputtering target further comprises less than 1000 ppm, preferably less than 400 ppm, or more preferably less than 100 ppm oxygen.

[0087]

[0094] Embodiment 18: The embodiment of any of embodiments 1-17, wherein the uniformity of scandium across the surface of the sputtering target varies by less than ±0.5 atomic % of scandium across the radius of the surface.

[0088]

[0095] Embodiment 19: Any of embodiments 1-18, wherein the sputtering target has a central axis through the thickness of the sputtering target and a diameter intersecting the central axis, and the uniformity of scandium across the central axis and diameter varies by less than ±0.5% by weight of scandium.

[0089]

[0096] Embodiment 20: The embodiment of any of embodiments 1-19, wherein the sputtering target has a diameter greater than 300 mm.

[0090]

[0097] Embodiment 21: A method for preparing a non-equilibrium complex, comprising: x Sc y wherein x is 0 to 3 and y is 1 to 2; and mixing the powder with the aluminum-containing first phase to form a composite precursor. applying at least one of heat and pressure to the composite precursor to solidify the material; and cooling the solidified composite precursor to form a non-equilibrium composite.

[0091]

[0098] Embodiment 22: The embodiment of embodiment 21, wherein the compound comprises Al2Sc, AlSc, AlSc2, or Sc, or a combination thereof, present in an amount greater than 1 mol %.

[0092]

[0099] While the present invention has been described in detail, modifications within the spirit and scope of the present invention will be readily apparent to those skilled in the art. In view of the relevant knowledge and references in the art set forth above in connection with the foregoing description, background, and detailed description, the disclosures of which are incorporated herein by reference in their entirety. It should also be understood that aspects of the present invention and some of the various embodiments and various features set forth below and / or in the appended claims may be combined in whole or in part or substituted for each other. In the foregoing description of various embodiments, embodiments that refer to separate embodiments may be combined with other embodiments as appropriate, as will be understood by those skilled in the art. Furthermore, those skilled in the art will appreciate that the foregoing description is by way of example only and is not intended to be limiting. [Mode of the invention] [1] An Al-Sc composite comprising 1.0 atomic % to 65 atomic % scandium (Sc) and 35 atomic % to 99 atomic % aluminum (Al), having a microstructure comprising a first phase and a second phase dispersed throughout the first phase, the second phase having the formula Alx Sc y wherein x is 0 to 3 and y is 1 to 2. [2] The composite of claim 1, wherein the second phase comprises ScAl3, ScAl2, ScAl, Sc2Al, or Sc, or a combination thereof. 3. The composite of claim 1, wherein the second phase comprises less than 60 mole % AlSc relative to the total moles of the second phase. [4] The composite of claim 1, wherein the second phase comprises ScAl2, ScAl, Sc2Al, or Sc, or a combination thereof. 5. The composite of claim 1, wherein the microstructure comprises 5% to 99% by volume of the first phase and 1% to 80% by volume of the second phase, as determined by quantitative image analysis. [6] The composite of 1, wherein the concentration of scandium in the second phase is higher than that predicted from an aluminum-scandium equilibrium phase diagram. [7] The composite of claim 1, wherein the concentration of scandium in the second phase is at least 1% higher than the concentration predicted from an aluminum-scandium equilibrium phase diagram. [8] The composite of claim 1, wherein the second phase comprises greater than 25 atomic percent scandium. [9] The composite of 1, wherein the second phase comprises greater than 1 mol% Al2Sc, AlSc, AlSc2, or Sc, or a combination thereof.

[10] The composite of 1, wherein the second phase comprises less than 85 mol% aluminum.

[11] The composite of 1, wherein the second phase further comprises 1.0 mol% to 70 mol% scandium nitride (ScN).

[12] The composite of claim 1, wherein the grains of the first aluminum matrix phase have a (110) crystallographic orientation.

[13] The composite of claim 1, wherein the grains of the first aluminum matrix phase are characterized by random crystallographic orientation.

[14] The composite of claim 1, wherein the second phase has a particle size ranging from 0.5 microns to 500 microns.

[15] The composite of claim 1, wherein the microstructure is substantially free of microcracks and fissures and / or oxide inclusions.

[16] The composite of 1, wherein the composite or sputtering target further comprises less than 1000 ppm, preferably less than 400 ppm, or more preferably less than 100 ppm oxygen.

[17] A method for producing a non-equilibrium complex, comprising: Formula Al x Sc y providing a second phase powder comprising a compound corresponding to the formula: mixing the powder with a first phase comprising aluminum to form a composite precursor; applying at least one of heat and pressure to the composite precursor to solidify the material; cooling the solidified composite precursor to form the non-equilibrium composite; A method comprising:

[18] The method of claim 17, wherein the compound comprises Al2Sc, AlSc, AlSc2, or Sc, or a combination thereof, present in an amount greater than 1 mol%.

[19] An Al-Sc composite sputtering target comprising 1.0 atomic % to 65 atomic % scandium (Sc) and 35 atomic % to 99 atomic % aluminum (Al), having a microstructure comprising a first phase and a second phase dispersed throughout the first phase, the second phase having the formula Al x Sc y wherein x is 0 to 3, and y is 1 to 2.

[20] The sputtering target of 19, wherein the uniformity of scandium across the surface of the sputtering target varies by less than ±0.5 atomic % of scandium across the radius of the surface.

Claims

1. A first phase of a free aluminum matrix, and a second phase comprising aluminum and scandium dispersed throughout the first phase; A sputtering target comprising: the sputtering target having 25 atomic % to 50 atomic % scandium (Sc); and Al ２ Al present in a larger amount than Sc intermetallic compounds ３ having a microstructure comprising Sc intermetallic compounds and 15% to 40% by volume of free aluminum; and the concentration of scandium in the second phase is at least 1% greater than the concentration predicted from an aluminum-scandium equilibrium phase diagram; Sputtering target.

2. 10. The sputtering target of claim 1, comprising at least 20% by volume of free aluminum.

3. 2. The sputtering target of claim 1, wherein the free aluminum grains have a (110) crystallographic orientation, or the free aluminum grains have a random crystallographic orientation.

4. 10. The sputtering target of claim 1, wherein the sputtering target comprises less than 1000 ppm oxygen, preferably less than 400 ppm oxygen, and more preferably less than 100 ppm oxygen.

5. The second phase is Al ２ The sputtering target of claim 1 , which is free of Sc.

6. 10. The sputtering target of claim 1, wherein the microstructure is free of microcracks and fissures and / or oxide inclusions.

7. The Al ３ 2. The sputtering target of claim 1, wherein Sc intermetallic compounds are dispersed throughout the free aluminum.

8. A method for manufacturing a sputtering target, said method comprising: mixing an aluminum and scandium intermetallic powder with scandium powder to form a precursor; solidifying the precursor with at least one of heat or pressure to form a solidified precursor; cooling the solidified precursor; crushing the cooled, solidified precursor together with free aluminum powder and processing to form the sputtering target; Including, The microstructure of the sputtering target is Aluminum and scandium, with 25 atomic % to 50 atomic % scandium; Al ２ Al present in a larger amount than Sc intermetallic compounds ３ Sc intermetallic compounds, and 15% to 40% by volume of free aluminum having method.

9. The method described in claim 8, wherein the steps of solidifying the precursor and cooling the solidified precursor are performed in a squeeze casting process, and the step of cooling the solidified precursor includes cooling the solidified precursor at a rate greater than 1°C / min.

10. The method of claim 8, wherein solidifying the precursor comprises heating to a temperature of 400°C to 900°C.

11. The method of claim 8, wherein solidifying the precursor comprises pressing to a pressure of 5000 kPa to 9000 kPa.

12. 9. The method of claim 8, wherein consolidating the precursor comprises heating to a temperature of 400° C. to 900° C. and pressing to a pressure of 5000 kPa to 9000 kPa.

13. The method of claim 8 , wherein solidifying the precursor comprises heat pressing.

14. 9. The method of claim 8, wherein the sputtering target comprises at least 20% by volume of free aluminum.

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