Nitridation of powder for making scandium aluminum nitride pulsed laser deposition target body

Abstract

Examples are disclosed that relate to forming a target body for use in pulsed laser deposition of scandium aluminum nitride films. One example provides a method of preparing a scandium nitride / aluminum nitride target body for a pulsed laser deposition (PLD) system. The method comprises heating a mixture of scandium metal powder and aluminum nitride powder under nitrogen-containing gas to nitridate the mixture of scandium metal powder and aluminum nitride powder, thereby forming a mixture of scandium nitride powder and aluminum nitride powder.

Description

Docket No. LRC24329PPCTNITRIDATION OF POWDER FOR MAKING SCANDIUM ALUMINUM NITRIDE PULSED LASER DEPOSITION TARGET BODYBACKGROUND

[0001] Pulsed laser deposition (PLD) can be used in semiconductor device manufacturing to deposit a film on a substrate. PLD involves exposing a target body to pulsed laser energy. The laser energy ablates the target body to form a plasma plume. Material in the plasma plume deposits on the substrate.SUMMARY

[0002] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.

[0003] Examples are disclosed that relate to forming a target body for use in pulsed laser deposition of scandium aluminum nitride films. One example provides a method of preparing a scandium nitride / aluminum nitride target body for a pulsed laser deposition (PLD) system. The method comprises heating a mixture of scandium metal powder and aluminum nitride powder under nitrogen-containing gas to nitridate the mixture of scandium metal powder and aluminum nitride powder, thereby forming a mixture of scandium nitride powder and aluminum nitride powder.

[0004] In some such examples, the method further comprises milling the mixture after nitridating the mixture to form a milled mixture of scandium nitride powder and aluminum nitride powder.

[0005] In some such examples, milling comprises mixing the mixture of scandium nitride powder and aluminum nitride powder with a solvent and ball milling.

[0006] Alternatively or additionally, in some such examples, the method further comprises passing the milled mixture through a sieve to filter out grains larger than a threshold grain size.

[0007] Alternatively or additionally, in some such examples, milling the mixture comprises milling the mixture to a selected D50 grain size of 5 microns or less.Docket No. LRC24329PPCT

[0008] Alternatively or additionally, in some such examples, the method further comprises hot pressing the milled mixture to form a target body.

[0009] Alternatively or additionally, in some such examples, heating the mixture comprises heating to a temperature of 1000-1400 °C for 1.5 hours or more under nitrogen (N2).

[0010] Alternatively or additionally, in some such examples, the mixture further comprises one or more of boron, lanthanum, or yttrium.

[0011] Alternatively or additionally, in some such examples, the mixture comprises scandium metal powder having a D50 grain size of 10 microns or less.

[0012] Alternatively or additionally, in some such examples, the mixture comprises aluminum nitride powder having a D50 grain size of 10 microns or less.

[0013] Another example provides a method of forming a scandium nitride / aluminum nitride (ScN / AlN) target body. The method comprises flowing nitrogen-containing gas over a mixture of scandium metal powder and aluminum nitride powder. The method further comprises heating the mixture under the nitrogencontaining gas to nitridate the mixture, thereby forming a mixture of scandium nitride powder and aluminum nitride powder. The method further comprises milling the mixture to reduce a D50 grain size of the scandium nitride powder and aluminum nitride powder. The method further comprises hot pressing the mixture of scandium nitride powder and aluminum nitride powder to form the ScN / AlN target body.

[0014] In some such examples, the nitrogen-containing gas comprises at least 99.99% N2.

[0015] Alternatively or additionally, in some such examples, the ScN / AlN target body comprises a density of 97% theoretical density or greater.

[0016] Alternatively or additionally, in some such examples, the ScN / AlN target body comprises a density of 99% theoretical density or greater.

[0017] Alternatively or additionally, in some such examples, the ScN / AlN target body comprises a D50 grain size of 10 microns or less.

[0018] Alternatively or additionally, in some such examples, the ScN / AlN target body further comprises one or more of lanthanum nitride, yttria nitride, or boron nitride.

[0019] Another example provides a target body for forming a scandium aluminum nitride film in a pulsed laser deposition process, the target body formed from grains of scandium nitride and grains of aluminum nitride, wherein the grains ofDocket No. LRC24329PPCT scandium nitride have a D50 grain size of 10 microns or less and the grains of aluminum nitride have a D50 grain size of 10 microns or less.

[0020] In some such examples, the target body comprises a density of 97% theoretical density or greater.

[0021] Alternatively or additionally, in some such examples, the target body comprises a density of 99% theoretical density or greater.

[0022] Alternatively or additionally, in some such examples, the grains of scandium nitride and grains of aluminum nitride each have a D50 size of 1 micron or less.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 schematically illustrates an example pulsed laser deposition (PLD) tool.

[0024] FIG. 2 shows a flow diagram of an example method for processing scandium metal powder and aluminum nitride powder to form a target body for use in a PLD process.

[0025] FIG. 3 schematically shows formation of a target body using the method of FIG. 2.

[0026] FIG. 4 shows a scanning electron microscope (SEM) image of a target body produced by nitridating a powder of scandium aluminum alloy to form scandium aluminum nitride.

[0027] FIG. 5 shows an SEM image of a target body produced using the method of FIG. 2.DETAILED DESCRIPTION

[0028] The terms “ablation”, “laser ablation”, and variants thereof may generally represent the removal of material from a target using laser energy. Material removed from a target by laser ablation can deposit on a substrate to form a film.

[0029] The term “grain size” may generally represent the size of an individual grain (particle) in a powder or a ceramic formed from a sintered powder. The term “D50 grain size” may generally represent the median grain size for which half of the grains are larger and half of the grains are smaller.

[0030] The term “hot press” may generally represent a process of sintering grains together by applying heat and pressure.Docket No. LRC24329PPCT

[0031] The terms “pulsed laser deposition” and “PLD” may generally represent a physical deposition process in which a material is ablated from a target by application of pulsed laser energy. At least some target material ablated by the laser adsorbs onto a substrate to form a film on the substrate.

[0032] The term “PLD tool” may generally represent a machine including a processing chamber and other hardware configured to enable PLD processing to be carried out in the processing chamber.

[0033] The term "substrate holder" may generally represent a structure for supporting a substrate in a processing chamber.

[0034] The term "target body" may generally represent a solid mass comprising material to be deposited on a substrate in a PLD process. The target is ablated by laser light to form a plasma plume. Chemical species in the plasma plume deposit on the substrate.

[0035] The term "target holder" generally represents any structure for supporting a target in a processing chamber.

[0036] As previously mentioned, pulsed laser deposition (PLD) involves using a pulsed laser to remove material from a target body and deposit the removed material onto a substrate. The removal of material from the target body using the laser can be referred to as ablation. The laser forms a plasma plume comprising the material removed from the target. Material in the plasma plume deposits on the substrate to form a film on the substrate.

[0037] One example use of PLD is in the deposition of films of piezoelectric materials, including aluminum nitride (AIN) and scandium aluminum nitride (ScAlN). AIN is a well-known piezoelectric thin film material. The piezoelectric performance can be significantly improved by doping with scandium as high as 50 atomic%. ScAlN films can be used, for example, as piezoelectric layers in acoustic filters for radiofrequency filter applications, and in micro-electro-mechanical systems such as miniature microphones and ultrasound transducers.

[0038] To enable the deposition of a ScAlN film by PLD, a target body comprising scandium, aluminum, and nitrogen is prepared. A target body can be formed from a powder or mixture of powders by compressing and sintering grains (particles) in the powder together to form a densified ceramic mass that can then be shaped into the target body.Docket No. LRC24329PPCT

[0039] Various factors can contribute to the quality of a PLD-deposited ScAlN film. For example, one factor is elemental purity of the target body, as impurities in the target body can be incorporated into the PLD film during laser ablation. Another factor is the density of the target body, as a target body that has relatively higher density can produce better quality PLD films than a target body that has a relatively lower density. This is due to denser target bodies having better optical absorption than less dense target bodies. In general, relatively smaller grain sizes in a powder help to form relatively denser target bodies compared to relatively larger grain sizes. Relatively larger grain sizes, as well relatively wider variability in grain size, can lead to local stresses, cracks, and voids in a target body. Cracks and voids can result in an unsuitably low density of a target body, for example, a density that is less than 97% of the theoretical density. A measured density can differ from theoretical density due to the porosity of the target body, where 100% theoretical density refers to the density of a pristine material that is substantially free of voids, cracks, and defects. Density of a target body can be measured using any suitable method, such as the Archimedes method in water (see, e.g., International Organization for Standardization (ISO) Standard No. 18754:2022). As such, it is useful to form a target body from high purity powder or powders comprising small, suitably consistent grain sizes. Examples of such powders include powders having D50 (median) grain sizes within a range of 0.5 micrometers (pm) - 50 pm and a size variance of 0.1 pm - 20 pm, as measured by a laser diffraction particle size analyzer.

[0040] However, it can be challenging and / or expensive to form PLD target bodies for depositing ScAlN films that meet desired specifications related to grain size, density, and purity. One option is to begin with a powder of scandium aluminum alloy and nitridate the powder to form scandium aluminum nitride powder. However, scandium aluminum alloy powders are susceptible to oxidation. Thus, preparing a target body from nitridation of scandium aluminum alloy powder risks introducing oxygen as an impurity. Further, scandium aluminum alloy powders can be difficult and expensive to source at high purity, and can have relatively large grain sizes, such as D50 grain sizes over 50 pm, as well as size variances outside of the range of 0.1 pm - 20 pm. As discussed above, relatively large, inconsistent grain sizes can lead to a relatively low- density target body.

[0041] Another option is to begin with powders of scandium nitride and aluminum nitride. However, scandium nitride powders may have similar issues relatedDocket No. LRC24329PPCT to high cost, impurities, relatively large grain sizes, and / or relatively inconsistent grain sizes. As such, a target body formed from commercially-sourced scandium nitride powder and aluminum nitride powder can have a density that is less than 97% of a theoretical density.

[0042] Accordingly, examples are disclosed that relate to forming a ScN / AlN target body with suitably small, consistent grain size, suitably high density, and suitably high purity using lower cost raw source materials than scandium aluminum alloy powders. In some examples, ScN / AlN target bodies having D50 grain sizes of 0.5 pm - 50 pm, grain size variances of 0.1 pm - 20 pm, densities of 97% - 100% of theoretical density, and / or purities of 95% - 100% (atomic %) can be formed. All ranges stated herein are inclusive of the endpoint values. Briefly, Sc metal powder and AIN powder are mixed to form a mixture. Sc metal powder may be available with higher purities, smaller grain sizes, and less expense than ScN powders. The mixture is heated under a nitrogen-containing gas to nitridate the powder. This forms a mixture of ScN powder and AIN powder. The nitridated mixture can then be milled, sintered (e.g. by hot pressing), and cut to obtain ScN / AlN target body. By nitridating a mixture of Sc metal powder and AIN powder, the process can be less expensive than other methods, such as nitridating an ScAl alloy powder. Further, the disclosed examples can yield a target body with smaller D50 grain sizes and / or more consistent grain sizes than the nitridation of an ScAl alloy powder. This can allow a target body of relatively higher density to be made compared to the nitridation of an ScAl alloy powder, which can help the target body absorb laser light efficiently and evenly to produce a high quality ScAlN film.

[0043] Prior to discussing these examples in detail, FIG. 1 shows a schematic view of an example PLD tool 100. PLD tool 100 comprises a processing chamber 102 for performing PLD processes on substrates. A target holder 104 and a substrate holder 106 are located within processing chamber 102. A target body 108 is arranged on target holder 104 during the PLD process. Further, a substrate 110 is arranged on substrate holder 106.

[0044] PLD tool 100 further comprises a laser 112 configured to direct laser light 114 through a laser entrance window 116 of processing chamber 102 and towards target holder 104. One or more optics 118 (shown here as a single component) can be used to focus laser light 114 to decrease a spot size of laser light 114 at target body 108.

[0045] Laser light 114 generates a plasma plume 120 and particles from target body 108 during the PLD process. A filter 122 blocks some particles from reachingDocket No. LRC24329PPCT substrate 110 while passing plasma plume 120 towards substrate 110. Chemical species in plasma plume 120 deposit on substrate 110 as a film. Filter 122 rotates in synchronization with laser pulses. As particles travel more slowly than plasma plume 120, an opening in filter 122 can rotate to a location between a laser spot on target body 108 and substrate 110 during laser illumination. In this manner, the opening in filter 122 can pass plasma plume 120. The opening in filter 122 then rotates away to block at least some of the slower-traveling particles.

[0046] Substrate holder 106 can be configured to move during the PLD process to expose a desired surface area of substrate 110 to plasma plume 120. PLD tool 100 further comprises a heater 124 arranged on substrate holder 106. Heater 124 is used to control a temperature of substrate 110.

[0047] PLD tool 100 can be configured to receive a flow of a processing gas from a processing gas source 138 during a PLD process. In some examples, the process gas comprises nitrogen. In other examples, the processing gas alternatively or additionally comprises argon, helium, neon, krypton, xenon, and / or other suitably inert gas. PLD tool 100 further comprises an exhaust system 140 configured to evacuate gases out of processing chamber 102. Processing gas source 138 and exhaust system 140 can be controlled to maintain a selected pressure within processing chamber 102 during a PLD process. In some examples, the pressure of processing chamber 102 can be maintained at a pressure within a range of 0.01-0.1 millibars. In other examples, pressures outside of this range can be used.

[0048] PLD tool 100 further comprises a controller 142 configured to control components of PLD tool 100. For example, controller 142 controls the flow of processing gas from processing gas source 138. Controller 142 is further configured to control laser 112, exhaust system 140, substrate holder 106, heater 124, and other components of PLD tool 100.

[0049] As mentioned above, the quality of a film deposited by PLD can depend on various properties of a target body, including grain size and optical absorption of different grains. Thus, the disclosed examples provide for the manufacture of a target body comprising grains of ScN and AIN with smaller and / or more consistent (lower variance) grain sizes than other methods. Due to the high energy of the laser beam, the scandium, aluminum, and nitrogen will mix in the plasma and deposit as a ScAlN film. Thus, although a target body may not be composed of ScAlN, the film formed on a substrate by PLD can be ScAlN.Docket No. LRC24329PPCT

[0050] FIG. 2 shows a flow diagram of an example method for forming a ScN / AlN target body. At 202, method 200 comprises obtaining scandium metal powder and aluminum nitride powder. Such raw materials may be less costly compared to methods that use scandium aluminum (ScAl) alloy metal powder. Additionally, it may be less costly to obtain scandium metal powder and aluminum nitride powder at high purity with less oxygen content compared to other possible raw materials, such as a powder of scandium aluminum alloy or scandium nitride powder.

[0051] In some examples, the aluminum nitride powder has a D50 grain size < 50 microns (pm). Additionally or alternatively, in some examples, the scandium metal powder has a D50 grain size < 50 pm. In some such examples, D50 grain sizes of one or both of the scandium or the aluminum nitride can be 10 pm or less. Further, in some such examples, grain sizes of one or both of the scandium or the aluminum nitride can be 1 pm or less. However, larger D50 grain sizes (> 50 pm) also can be used, as the D50 grain size can be reduced via milling, crushing, and / or grinding in a later processing step. In some examples, grain sizes variances of one or both of the scandium or the aluminum nitride can be 0.1 pm - 20 pm. In other examples, a variance outside this range can be used.

[0052] In some examples, the scandium metal powder and / or aluminum nitride powder can comprise one or more dopants. Dopants can be included to help control various properties of the ScAlN film, such as a crystallinity of the ScAlN film. Alternatively or additionally, dopants can help control various processing steps, such as the nitridation reaction. In such some examples, at 204, the scandium metal powder can comprise lanthanum and / or yttrium as dopants. Alternatively or additionally, in some such examples, at 206, the aluminum nitride powder can comprise boron as a dopant.

[0053] Continuing, at 208, method 200 comprises mixing the scandium metal powder and aluminum nitride powder to form a mixture. Mixing scandium metal powder with aluminum nitride powder prior to nitridation of the scandium metal powder can help to control the exothermic nitridation reaction of scandium during nitridation. Controlling the exothermic nitridation reaction can help avoid agglomeration of grains to larger D50 grain sizes. In some examples, the powder can be milled, crushed, and / or ground before and / or after mixing to obtain a selected D50 grain size. As mentioned above, the use of powders with suitably small, consistent grain sizes, such as D50 grain sizes and variances within the above ranges, can help to formDocket No. LRC24329PPCT a denser target body with a higher optical absorption coefficient for a PLD process compared to the use of powders with D50 grain sizes and / or grain size variation outside of these ranges.

[0054] Method 200 further comprises, at 210, nitridating the mixture of scandium metal powder and aluminum nitride powder to obtain a nitridated mixture of scandium nitride powder and aluminum nitride powder. As such, the nitridation reaction converts scandium to scandium nitride. Nitridation is performed by heating the mixture under a nitrogen-containing gas. Example nitrogen-containing gases include ammonia, hydrazine, and molecular nitrogen (N2). In some examples, the nitrogencontaining gas comprises 99.9% N2, 99.99% N2, or even 99.999% N2. A relatively high purity nitrogen gas can help to form a relatively high purity scandium nitride powder with relatively low contamination from elements such as oxygen.

[0055] Any suitable reaction conditions can be used for the nitridation. In some examples, at 212, the mixture is heated to a temperature within a range of 800 °C to 1500 °C. In some such examples, a temperature within a range of 1200 °C to 1400 °C is used. Further, in some examples, the nitridation step can be performed for 1-3 hours, or longer. In other examples, temperatures and / or durations outside these ranges can be used. Nitridation can be performed in any suitable reaction system. In some examples, the nitridation can be performed in a tube furnace through which the nitrogencontaining gas is flowed.

[0056] At 214, method 200 further comprises milling the mixture of scandium nitride powder and aluminum nitride powder. Milling can help reduce the D50 grain size of the scandium nitride powder and aluminum nitride powder. In some examples, milling, crushing and / or grinding at 214 is performed until a target D50 grain size is achieved. Examples include a D50 grain size of 50 pm, 10 pm, 5 pm, or 1 pm or less. Grain size can be measured using any suitable particle size analyzer (PSA), such as a PSA based on dynamic light scattering, static light scattering, or laser diffraction. The presence of the desired ScN and AIN phases can be confirmed using powder X-ray diffraction. Any suitable milling technique can be used. In some examples, at 216, the mixture is mixed with a solvent and ball milled. Example solvents include ethanol, propanol, hexane, and heptane. Ball milling can be performed using ceramic balls (e.g., alumina (AI2O3) ceramic balls). After ball milling, the mixture can be dried and / or heated to remove solvent. In some examples, the milled mixture optionally can beDocket No. LRC24329PPCT passed through a sieve to filter out grains larger than a threshold grain size. In some examples, a sieve can be used to remove milling balls.

[0057] In some examples, at 217, method 200 can return to step 210 for further nitridation. In this manner, nitridation and milling can be performed iteratively. Milling can expose new surfaces for nitridation. As such, nitridating the mixture after milling can help to nitridate newly exposed scandium metal surfaces. In some examples, performing nitridation and milling iteratively can help achieve a more complete nitridation process than a single nitridation step. Additionally, in some examples, a sieve can be used to filter out larger grains, and the larger grains can be further milled and / or further ni tri dated.

[0058] Continuing, at 218, method 200 further comprises hot pressing the mixture of scandium nitride powder and aluminum nitride powder to form a target body comprising ScN / AlN grains. Hot pressing combines heat and pressure to assist in sintering grains to form a densified body. In some examples, the target body comprises a density of > 97% of theoretical density (approximately 3% void space or less). In some such examples, the density is > 99% of theoretical density. In some examples, the D50 grain size is 50 pm or less. In some such examples, the D50 grain size is 10 pm or less. In some such examples, the D50 grain size is 5 pm or less. Further, in some such examples, the D50 grain size is 1 pm or less.

[0059] In various examples, powder can be compacted using cold isostatic pressing (CIP). CIP uses pressurized fluid to apply pressure isostatically to powder in a “dry bag” to compact the powder prior to sintering. In some examples, CIP can be used to compress powder comprising added organic pressing agents (such as paraffin or polyethylene glycol (PEG)). In some examples, the grains are hot pressed and afterward densified by Hot Isostatic Pressing (HIP) to further densify the material. In some examples, the grains are sintered by Hot Isostatic Pressing (HIP). HIP applies pressure onto the grains in all directions. This allows for a more uniform density within the produced target body. For example, the mixture of scandium nitride powder and aluminum nitride powder synthesized as disclosed herein can be arranged in a flexible mold. The flexible mold is then positioned within a pressure vessel, which is supplied with a pressurized fluid. The flexible mold can deform such that the pressurized fluid compresses the grains isostatically into a target body. In some examples, an outgassing step can be performed on the flexible mold to remove oxygen and / or organic pressing agents prior to HIP. Outgassing can comprise, for example, baking the flexible moldDocket No. LRC24329PPCT under nitrogen. This can lower oxygen exposure during HIP and help avoid oxygen impurities in the target body. In some examples, hot pressing can be performed at a pressure of 10 - 100 MPa. In other examples, a pressure outside this range can be used. In some examples, hot pressing is performed at a temperature of 1600 °C - 2300 °C. In other examples, a temperature outside this range can be used. In some examples, hot pressing can achieve a density of > 97% (or > 99%). In some examples, HIP in a flexible mold can achieve a density of > 97% (or > 99%). In further examples, a combination of hot pressing, outgassing, CIP, and / or HIP can be used. For example, a powder can be hot pressed followed by HIP to a density of > 97% (or > 99%). In some examples, a powder can be treated using CIP followed by outgassing of organic pressing agents. After outgassing, the powder can be hot pressed to a density of > 97% (or > 99%). In some such examples, after hot pressing, the compressed powder is further treated by HIP.

[0060] After hot pressing, the target body can be further processed to prepare the target body for use in PLD. At 220, method 200 optionally comprises cutting and / or grinding the target body. Cutting and grinding can help form a relatively smooth surface suitable for laser ablation in a PLD tool. Further, a target body can be cut into a plurality of smaller target bodies. At 222, method 200 optionally comprises analyzing the target body. The target body can be analyzed, for example, to characterize elemental composition, density, surface roughness, and D50 grain size. Examples of elemental analysis methods include energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence, and X-ray photoelectron spectroscopy. Elemental analysis can be performed, for example, to determine whether proportions of scandium, aluminum, and nitrogen within a target body are within a selected range. Further, elemental analysis also can be used to determine whether impurities such as oxygen, carbon, and / or silicon are below threshold values. Density can be measured as weight / volume. Grain size of the target body can be measured from photomicrographs of a polished test piece. As examples, the mean linear intercept method or mean equivalent circle diameter method can be used to analyze a 2-dimensional section of a target body and measure grain size (see, e.g., DIN EN ISO Standard No. 13383-1 :2016-11 “Fine ceramics (advanced ceramics, advanced technical ceramics) - Microstructural characterization - Part 1: Determination of grain size and size distribution (ISO 13383-1 :2012)”). Measured grain sizes may differ from D50 grain sizes due to grain shape and degree of microstructural anisotropy. Surface roughness can be measured using a profilometer or laser scanner,Docket No. LRC24329PPCT for example. At 224, method 200 optionally comprises packaging the target body for shipping. In some examples, the target body is cleaned and packaged under an inert gas to help avoid oxidation.

[0061] Next, at 226, method 200 comprises using the target body in a pulsed laser deposition process to deposit scandium aluminum nitride film onto a substrate. PLD tool 100 is an example of a tool that can be used to perform step 226.

[0062] FIG. 3 schematically shows formation of a target body using method 200. As shown, scandium metal powder 302 is mixed with aluminum nitride powder 304 to form a mixture 306. Example D50 grain sizes for the aluminum nitride powder and the scandium metal powder are described above. As indicated at 308, the mixture is heated under a nitrogen-containing gas (e.g., step 210 of method 200) to form a mixture 310 of scandium nitride and aluminum nitride. Example heating conditions are described above. As indicated at 312, the mixture 310 then is hot pressed (e.g., step 218 of method 200) to form a target body 314. Some steps, such as milling, cutting, and grinding, are not depicted in FIG. 3. The target body 314 comprises grains of scandium nitride and grains of aluminum nitride. Due to hot pressing, target body 314 is denser than mixture 310. Further, due to the small, consistent grain size of scandium nitride and aluminum nitride in mixture 310 (D50 grain size of 0.5 pm - 50 pm with grain size variances of 0.1 pm - 20 pm), the target body 314 comprises a relatively high density (e.g., > 97% theoretical density).

[0063] FIGS. 4-5 show scanning electron microscope (SEM) images of target bodies. First, FIG. 4 shows a SEM image of a target body 400 produced by nitridating a powder of scandium aluminum alloy having a grain size of approximately 149 pm (100 mesh). FIG. 5 shows a SEM image of a target body 500 produced using method 200. As can be seen, the grain size of target body 500 is smaller and more consistent than the grain size of target body 400. For example, many grains of the target body 400 have a size > 20 pm (e.g., grain 402), whereas many grains of target body 500 have a size < 10 pm (e.g., grain 502). Additionally, target body 500 comprises a relatively high theoretical density, as evident by the relatively small number and sizes of voids 504 shown in FIG. 5.

[0064] Thus, the disclosed examples provide for a method of forming a target body for use in PLD of scandium aluminum nitride films. As the manufacturing process includes nitridation of scandium metal powder and aluminum nitride powder, the process can source scandium metal powder and aluminum nitride powder as startingDocket No. LRC24329PPCT materials. Scandium metal powder and aluminum nitride powder can be obtained at relatively higher purity and at relatively lower cost compared to scandium aluminum alloy powders. This can help provide for less expensive ScN / AlN target bodies and less expensive PLD-deposited ScAlN films than other methods. Further, the disclosed examples can provide for forming a ScN / AlN target body with relatively smaller, more consistent D50 grain sizes and higher densities compared to ScN / AlN target bodies manufactured using other methods. Such grain sizes and densities also can help contribute to a high quality ScAlN film by PLD.

[0065] It will be understood that the configurations and / or approaches described herein are exemplary in nature, and that these specific examples or examples are not to be considered in a limiting sense, because numerous variations are possible. The specific routines or methods described herein may represent one or more of any number of processing strategies. As such, various acts illustrated and / or described may be performed in the sequence illustrated and / or described, in other sequences, in parallel, or omitted. Likewise, the order of the above-described processes may be changed.

[0066] The subject matter of the present disclosure includes all novel and non- obvious combinations and sub-combinations of the various processes, systems and configurations, and other features, functions, acts, and / or properties disclosed herein, as well as any and all equivalents thereof.

Claims

Docket No. LRC24329PPCTCLAIMS:

1. A method of preparing a scandium nitride / aluminum nitride target for a pulsed laser deposition (PLD) system, the method comprising: heating a mixture of scandium metal powder and aluminum nitride powder under nitrogen-containing gas to nitridate the mixture of scandium metal powder and aluminum nitride powder, thereby forming a mixture of scandium nitride powder and aluminum nitride powder.

2. The method of claim 1, further comprising milling the mixture after nitridating the mixture to form a milled mixture of scandium nitride powder and aluminum nitride powder.

3. The method of claim 2, wherein milling comprises mixing the mixture of scandium nitride powder and aluminum nitride powder with a solvent and ball milling.

4. The method of claim 2, further comprising passing the milled mixture through a sieve to filter out grains larger than a threshold grain size.

5. The method of claim 2, wherein milling the mixture comprises milling the mixture to a selected D50 grain size of 5 microns or less.

6. The method of claim 2, further comprising hot pressing the milled mixture to form a target body.

7. The method of claim 1, wherein heating the mixture comprises heating to a temperature of 1000-1400 °C for 1.5 hours or more under nitrogen (N2).

8. The method of claim 1, wherein the mixture further comprises one or more of boron, lanthanum, or yttrium.

9. The method of claim 1, wherein the mixture comprises scandium metal powder having a D50 grain size of 10 microns or less.Docket No. LRC24329PPCT10. The method of claim 1, wherein the mixture comprises aluminum nitride powder having a D50 grain size of 10 microns or less.

11. A method of forming a scandium nitride / aluminum nitride (ScN / AlN) target body, the method comprising: flowing nitrogen-containing gas over a mixture of scandium metal powder and aluminum nitride powder; heating the mixture under the nitrogen-containing gas to nitridate the mixture, thereby forming a mixture of scandium nitride powder and aluminum nitride powder; milling the mixture to reduce a D50 grain size of the scandium nitride powder and aluminum nitride powder; and hot pressing the mixture of scandium nitride powder and aluminum nitride powder to form the ScN / AlN target body.

12. The method of claim 11, wherein the nitrogen-containing gas comprises at least 99.99% nitrogen (N2).

13. The method of claim 11, wherein the ScN / AlN target body comprises a density of 97% theoretical density or greater.

14. The method of claim 13, wherein the ScN / AlN target body comprises a density of 99% theoretical density or greater.

15. The method of claim 11, wherein the ScN / AlN target body comprises a D50 grain size of 10 microns or less.

16. The method of claim 11, wherein the ScN / AlN target body further comprises one or more of lanthanum nitride, yttria nitride, or boron nitride.

17. A target body for forming a scandium aluminum nitride film in a pulsed laser deposition process, the target body formed from grains of scandium nitride and grains of aluminum nitride, wherein the grains of scandium nitride have a D50 grain size of 10 microns or less and the grains of aluminum nitride have a D50 grain size of 10 microns or less.Docket No. LRC24329PPCT18. The target body of claim 17, wherein the target body comprises a density of 97% theoretical density or greater.

19. The target body of claim 18, wherein the target body comprises a density of 99% theoretical density or greater.

20. The target body of claim 17, wherein the grains of scandium nitride and grains of aluminum nitride each have a D50 size of 1 micron or less.

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