Refractory metal plates

Abstract

A refractory metal plate is disclosed having a center, a thickness, an edge, a top surface, and a bottom surface, wherein the thickness is less than or equal to 1.6 cm as measured from the top surface to the bottom surface. The refractory metal plate characterized by a sputtering deviation factor based on <100> texture, <110> texture, and <111> texture of less than 1. In addition, the refractory metal plate contains at least one impurity element in an amount up to 500 ppm.

Description

Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) REFRACTORY METAL PLATES PRIORITY CLAIM

[0001] This application claims priority to U.S. Provisional App. No.63 / 610,817, filed on December 15, 2023, the entirety of which is incorporated herein by reference. FIELD

[0001] The present disclosure relates to plates of refractory metals and metal alloys that are suitable for sputtering targets. In particular, the refractory metal plates with improved sputtering performance and uniformity through thickness. BACKGROUND

[0002] Sputtering processes are employed to deposit thin films from a target onto substrates, such as a silicon wafer, to manufacture a variety of devices. Sputtering processes typically involve bombarding a solid sputtering target body with energized particles to eject atoms from the target body. There are several parameters that affect sputtering, such as purity, interstitial content, crystal plane orientation, thickness uniformity, and / or grain size. By manipulating the target material one can control sputter deposition to obtain fine control over the growth and microstructure of the thin films.

[0003] Sputtering targets may be made by ingot metallurgy, pursuant to which an ingot is formed (e.g., by electron beam melting of a metal), and thereafter thermomechanically processed for achieving a desired texture. Commercially available targets comprising refractory metals are processed from an ingot obtained by subjecting a raw material to melting and casting, which may include thermomechanical processes such as forging, annealing, rolling, heat-treating, and other finishing processes.

[0004] Sputtering targets also may be made from powder metal starting materials, which are suitably consolidated to form a resulting target. When powder metals are used as starting materials it is typically desirable to employ high purity powders. For example, it is desired to employ powders that have a low content of undesired metallic impurities, and / or a low content of oxygen. 1 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446)

[0005] U.S. Pat. No.9,095,885 describes a refractory metal plate. The plate has a center, a thickness, an edge, a top surface, and a bottom surface, and has a crystallographic texture (as characterized by through thickness gradient, banding severity; and variation across the plate, for each of the texture components 100 / / ND and 111 / / ND, which is substantially uniform throughout the plate.

[0006] U.S. Pat. No.10,023,953 describes a method for making a sputtering target including steps of encapsulating and hot isostatically pressing at least one mass of metal powder (e.g., tantalum), having a particle size ranging from about 10 to about 1000 μm, with at least about 10 percent by weight of particles having a particle size greater than about 150 μm (for example, about 29 to about 56 percent (e.g., about 35 to about 47 percent) by weight of the particles in the at least one mass of metal powder having a particle size that is larger than 150 microns, but below about 250 μm), for defining at least a portion of a sputtering target body, having an essentially theoretical random and substantially uniform crystallographic texture.

[0007] There is therefore a need in the art for refractory metal plates that have improved sputtering rates. This disclosure addresses those needs. SUMMARY

[0008] In general, the disclosure relates to a refractory metal plate having a uniformity of grain throughout thickness. In one embodiment, the refractory metal plate has a sputtering deviation factor of less than 1.

[0009] In one aspect there is provided a refractory metal plate comprising a center, a thickness, an edge, a top surface and a bottom surface, the refractory metal plate characterized by a sputtering deviation factor based on <100> texture, <110> texture, and <111> texture of less than 1, more preferably less than 0.6, and at least one impurity element in an amount up to 500 ppm, preferably the total amount of impurity elements may be up to 500 ppm, e.g., up to 100 ppm or up to 50 ppm. In one embodiment, the metal plate may have a grain size greater than or equal to 10 μm. In one embodiment, the thickness may be less than or equal to 1.6 cm as measured from the top surface to the bottom surface. In one embodiment, the thickness of the refractory metal plate may be from 0.25 cm to 1.5 cm. 2 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446)

[0010] In one embodiment, the refractory metal plate comprises at least one refractory metal comprising tantalum, scandium, niobium, titanium, hafnium, ruthenium, or rhenium. In one embodiment, the refractory metal plate may have a purity that is at least 99.95% or more, based on the total metals of the refractory metal plate. In one embodiment, the at least one impurity element may comprise silicon, phosphorus, boron, yttrium, ion, nickel, chromium, tungsten, molybdenum, niobium, copper, vanadium, hafnium, titanium, ruthenium, or rhenium. Preferably, the impurity element is different from the refractory metal. In one embodiment, the refractory metal plate may comprise a mixture of the impurity elements. The top and / or bottom surfaces of the refractory metal plate may comprise less than 25% of the total amount of the at least one impurity element.

[0011] In one embodiment, the area fraction total of the <100> texture, the <110> texture, and the <111> texture, represents 40% or more of the total grains, e.g., preferably from 40% to 90% or more preferably from 40% to 60%. In one embodiment, the area fraction of the <100> texture is greater than the area fraction of the <110> texture or the <111> texture. In addition, the area fraction of the <110> texture may be 20% or less based on the total grains. The sputtering deviation factor may be based on the <100> texture, the <110> texture, and the <111> texture which provides an indicator of uniformity.

[0012] In one aspect there is provided a refractory metal plate comprising a center, a thickness, an edge, a top surface and a bottom surface, the refractory metal plate characterized by a sputtering deviation factor based on <100> texture, <110> texture, and <111> texture of less than 0.6, and at least one impurity element in an amount up to 100 ppm, wherein the metal plate may have a grain size greater than or equal to 10 μm, and wherein the thickness may be less than or equal to 1.6 cm as measured from the top surface to the bottom surface.

[0013] In one aspect there is provided a method for identifying nonuniformity in a refractory metal plate comprising calculating a reference sputtering rate, measuring an area fraction of the refractory metal plate to determine a sample sputtering rate and comparing the reference sputtering rate with the sample sputtering rate to identify the refractory metal plate. In one embodiment, the reference sputtering rate comprises calculating sputtering yield within 15° of an orientation of at least two textures for a reference plate, preferably a <100> texture, a <110> texture, and a <111> texture, measuring an area fraction of an <100> texture, <110> texture, and <111> texture using a cross-section of the reference plate in the normal direction, normalizing 3 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) the area fraction of the reference plate based on the orientation of the <100> texture, the <110> texture, and the <111> texture, and determining a reference sputtering rate based on the at least the normalized area fraction of the reference plate. Once the reference sputtering rate is determined, the reference sputtering rate may be used to determine uniformity between batches of plates or within the same plate. In one embodiment, process for identifying nonuniformity in a refractory metal plate comprises measuring an area fraction of an <100> texture, <110> texture, and <111> texture using a cross-section of the refractory metal plate in the normal direction, normalizing the area fraction of the refractory metal plate based on the orientation of the <100> texture, the <110> texture, and the <111> texture, determining a sample sputtering rate based on at least the normalized area fraction of the refractory metal plate, and comparing the reference sputtering rate with the sample sputtering rate to identify the refractory metal plate is uniform when less than 1, or more preferably when less than 0.6.

[0014] These and other non-limiting characteristics are more particularly described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The invention is further illustrated by the following drawings in which:

[0016] FIG.1 is an illustration of a sputtering target having a refractory metal plate in accordance with embodiments disclosed herein; and

[0017] FIG.2 is a graph of the area percentages for <100>, <110> and <111>, of the refractory metal plate in accordance with Example 1.

[0018] FIG.3 is a graph of the area percentages for <100>, <110> and <111>, of the refractory metal plate in accordance with Comparative Example A. DETAILED DESCRIPTION

[0019] The crystallographic texture of a refractory metal plate used as a sputtering target is of great importance to the sputtering performance, particularly to the uniformity of thickness of the thin films deposited on substrates. To achieve high performance and reliability, refractory metal plates with uniform texture throughout its volume are desired. In one embodiment, there is provided a refractory metal plate having a uniform texture that is characterized by a sputtering deviation factor based on <100> texture, <110> texture, and <111> texture of less than 1. The sputtering deviation factor is a single value that can represent one or more textures. As used 4 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) herein the sputtering deviation factor is based on<100> texture, <110> texture, and <111> texture, unless otherwise noted. The sputtering deviation factor can be used to compare the uniformity at different locations of a refractory metal plate and uniformity from plate to plate.

[0020] In one embodiment, the sputtering deviation factor may be based on <100> texture, <110> texture, and <111> texture. The sputtering deviation factor may be less than 1, e.g., less than 1.1, greater than 0.99, less than 0.95, less than 0.9, less than 0.75, less than 0.7 or less than or equal to 0.6. In terms of ranges, the sputtering deviation factor may be from greater than 0 to less than 1, e.g., from 0.1 to less than 1, from 0.25 to 0.95, from 0.3 to 0.7, or from 0.4 to 0.6.

[0021] The sputtering deviation factor may be an indicator of deposition stability through target life. The higher number indicates less stability and poor deposition, while sputtering deviation factor of less than 1 indicate good stability. Accordingly, having a sputtering deviation factor of less than 1 indicates an absence of textural banding.

[0022] The sputtering deviation factor may be based on at least two different textures, such as <100> texture, <110> texture, and <111> texture. Preferably, the <100> texture, <110> texture, and <111> texture in combination represent 40% or more of the total grain of the refractory metal plate. In one embodiment, the combination of these textures may be 45% or more of the total grain of the refractory metal plate, e.g., 50% or more, 55% or more, 65% or more, 70% or more, or 75% or more. In terms of ranges the combination of the <100> texture, <110> texture, and <111> texture may be from 40% to 90% of the total grains, e.g., from 45% to 85%, from 50% to 85%, from 55% to 85%, from 60% to 85% or from 60% to 80%. In one embodiment, the combination of the <100> texture, <110> texture, and <111> texture may preferably be from 40% to 60% of the total grains.

[0023] In one embodiment, the area fraction of the <100> texture may be greater than the area fraction of the <110> texture. The area fraction of the <110> texture may be 20% or less based on the total grains, more preferably 15% or less. In one embodiment, the area fraction of the <100> texture may be greater than the area fraction of the <111> texture or more preferably greater than the area fraction of the <110> and <111> texture.

[0024] Advances have been made in measuring texture using EBSD (electron back-scatter diffraction), and the measurements can be used in such a way that the uniformity of texture can be described quantitatively. EBSD has an advantage over X-ray diffraction in that EBSD can 5 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) measures texture grain-by-grain. Accordingly, the textures of the refractory metal plate may be made using EBSD.

[0025] In one embodiment, there is provided a method for determining the sputtering deviation factor. The sputtering deviation factor may be used to identify nonuniformity in a refractory metal plate. The nonuniform refractory metal plate may be non-conforming and have less desirable performance. The sputtering deviation factor may be determined by calculating a reference sputtering rate. The reference sputtering rate may be calculated using at least two orientations, preferably at least three orientations. This provides a useful number for identifying nonuniformity. The reference sputtering rate may be used to establish a reference for uniformity that can efficiently and effectively identify nonuniformity in a refractory metal plate between batches or within the same refractory metal plate.

[0026] In one embodiment, the calculating a reference sputtering rate may be done by the following process. First, the sputtering yield is calculated within 15°, more preferably within 10° or within 8°, of at least two different orientations for a reference plate. The reference plate is known to have the desired uniformity. In one embodiment, the orientations may be a <100> texture, a <110> texture, and a <111> texture. For purposes of the present disclosure the reference sputtering rate may be understood with reference to the <100> texture, the <110> texture, and the <111> texture, but it is contemplated that other orientations may be used. Next, the process measures an area fraction of an <100> texture, <110> texture, and <111> texture using a cross-section of the reference plate in the normal direction. Next, the process normalizes the area fraction of the reference plate based on the orientation of the <100> texture, the <110> texture, and the <111> texture. The process further comprises determining a reference sputtering rate based on at least the normalized area fraction of the reference plate. In one embodiment, the process may determine a reference sputtering rate based on at least the sputtering yield and normalized area fraction of the reference plate. Typically, the reference sputtering rate may be from about 1.0 to 1.2, e.g., from 1.0 to 1.1. It should be understood that reference sputtering rate may be calculated separately for reference plates may of different refractory metals.

[0027] Once the reference sputtering rate is calculated, this may be used to identifying nonuniformity in a refractory metal plate. The process may comprise measuring an area fraction of at least two different orientations using a cross-section of the refractory metal plate in the normal direction. In one embodiment, at least of one the different orientations should be similar 6 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) to the orientations measured in the reference plate. More preferably, the same orientations may be used, such as an <100> texture, <110> texture, and <111> texture. Once the area fractions are measured, the process comprises normalizing the area fraction of the refractory metal plate based on the orientation of the <100> texture, the <110> texture, and the <111> texture followed by determining a sample sputtering rate based on the at least the normalized area fraction of the refractory metal plate. A histogram of the sample sputtering rate may be used as an indicator of deposition stability and uniformity. This may be used to determine uniformity throughout the lifetime of the refractory metal plate. The process further comprises comparing the reference sputtering rate with the sample sputtering rate to identify the refractory metal plate is uniform when less than 1, and more preferably less than 0.6. The process of using the sputtering deviation factor provides a single value to represent multiple texture variations and provides a useful overall performance.

[0028] One or more cross-sections may be measured. In one embodiment, the cross-sections may be measured using a gradient map of the textures.

[0029] The refractory metal plate may comprise a metal or metal alloy of tantalum, scandium, niobium, titanium, hafnium, ruthenium, or rhenium. Preferably, the refractory metal plate comprises a metal or metal alloy of tantalum or niobium. The purity of the refractory metal plate may be at least 99.95% pure or more based on the total metal content of the refractory metal plate, e.g., 99.99% pure or more, or 99.995% pure or more.

[0030] In one aspect of the present invention there is provided a refractory metal plate having a center, a thickness, an edge, a top surface, and a bottom surface. In one embodiment, the thickness may be less than or equal to 1.6 cm as measured from the top surface to the bottom surface of the refractory metal plate. Accordingly, in preferred embodiments, the thickness may be less than or equal to 1.5 cm, e.g., less than or equal to 1.4 cm, less than or equal to 1.3 cm, less than or equal to 1.2 cm, or less than or equal to 1.1 cm. In one embodiment, the thickness of the refractory metal plate may be from 0.02 cm to 1.6 cm, e.g., from 0.05 to 1.5 cm, from 0.05 cm to 1.4 cm, from 0.1 cm to 1.4 cm or from 0.2 to 1.3 cm. The thickness of the refractory metal plate should be greater than 0.2 cm to maintain a low distortion.

[0031] In one embodiment, the top surface may be finished to form a planar surface. In one embodiment, the bottom surface may be bonded to a backing plate. The bonding technique may involve diffusion-bonding, brazing, welding, soldering, brazing, mechanical fastening, epoxy 7 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) bonding, friction welding, or explosion bonding. Once bonded to the backing plate, a sputtering target is formed. The backing plate may comprise copper, aluminum, titanium molybdenum, zinc, or combinations or alloys thereof. In one embodiment, the backing plate may comprise a copper-zinc alloy or an aluminum alloy of the 2000, 6000 or 7000 series. Preferably, the backing plate is a different material than the refractory metal. The backing plate is configured to hold the refractory metal plate in a position suitable for deposition. In addition, the backing plate may provide mechanical strength, electrical conductivity, and thermal conductivity to the sputter target. Heat treatment may be used to provide the backing plate with a higher mechanical strength than the refractory metal plate.

[0032] In one embodiment, the refractory metal plate may be a rounded disc with the edge extending radially from the center. The maximum diameter of rounded disc may be from 2.5 cm to 45 cm, e.g., from 2.5 cm to 40 cm, from 2.5 cm to 30 cm, from 5 cm to 25 cm or from 10 cm to 20 cm. In one embodiment, the refractory metal plate may be rectangular with the opposing edges being substantially parallel.

[0033] In one aspect of the present invention there is provided a refractory metal plate having a grain size of greater than or equal to 10 μm. The grain size of the refractory metal plate may affect the sputtering deviation factor thereby the uniformity of the sputtering erosion and the ease of sputtering. Preferably, the grain size is maintained to be greater than or equal to 10 μm, e.g., greater than or equal to 15 μm, greater than or equal to 20 μm, greater than or equal to 25 μm, or greater than or equal to 30 μm. In one embodiment, at least 90% of the grains have a grain size of less than or equal to 120 microns, e.g., less than or equal to 110 μm, less than or equal to 100 μm, or less than or equal to 90 μm. In terms of ranges, the refractory metal plate may have an average grain size ranging from 10 to 120 μm, e.g., from 15 to 120 μm, or from 20 to 120 μm, from 30 to 120 μm, from 40 to 120 μm or from 50 to 120 μm. Grain size measurements are made according to ASTME112-12.

[0034] In one aspect of the present invention there is provided a refractory metal plate having at least one impurity element. The impurity elements refer to metallic impurities. In one embodiment, the impurity element may comprise silicon, phosphorus, boron, yttrium, iron, nickel, chromium, tungsten, molybdenum, niobium, copper, vanadium, hafnium, titanium, ruthenium, or rhenium. In preferred embodiments, the impurity element for tantalum or niobium metal plates may be nickel, chromium, tungsten, molybdenum, or titanium. The impurity 8 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) element should be an element that is different from the at least one refractory metal. In one embodiment, the impurity element may form a nano-alloy to improve heat stability of the grains. In one embodiment, the grain size may be stable up to temperatures of 1260°C, e.g., up to 1250°C, up to 1200°C, or up to 1060°C. In one embodiment, the grain size may be stable between temperature of 1000°C to 1260°C, e.g., from 1050°C to 1260°C or from 1050°C to 1250°C.

[0035] To maintain a sputtering deviation factor, the amount of the impurity element may be in an amount up to 500 ppm based on the total weight of the refractory metal plate, preferably up to 475 ppm, up to 450 ppm¸ up to 400 ppm, up to 350 ppm, up to 250, up to 100 or more preferably up to 50 ppm. The detectable limit of impurities is typically around 0.05 ppm, and the amount of the impurity element may be greater than the detectable limit. In preferred embodiments, the impurity element may be in an amount from 1 ppm to 500 ppm, e.g., from 1 ppm to 450 ppm, from 1 ppm to 350 ppm, from 1 ppm to 250 ppm, from 1 ppm to 100 ppm, from 1 ppm to 50 ppm, or from 5 ppm to 45 ppm. In one embodiment, refractory metal plate may contain one or more impurity elements and the total amount of all the impurities elements may be up to 500ppm, e.g., 475 ppm, up to 450 ppm ̧up to 400 ppm, up to 350 ppm, up to 250, up to 100 or morepreferably up to 50 ppm. The total amount of impurities may be from 1 ppm to 500 ppm, e.g., from 1 ppm to 450 ppm, from 1 ppm to 350 ppm, from 1 ppm to 250 ppm, from 1 ppm to 100 ppm, from 1 ppm to 50 ppm, or from 5 ppm to 45 ppm.

[0036] The distribution of the impurity in the sputtering may be uniform through thickness. Accordingly, there sputtering target does not have concentrated regions of impurities. In one embodiment, the refractory metal plate has a top surface contains less than 25% of the total amount of the at least one impurity element. In a similar manner, the bottom surface contains less than 25% of the total amount of the at least one impurity element. Having an excessive amount of impurities in the surfaces may reduce sputtering deviation factor.

[0037] In one embodiment, the refractory metal plate may have an interstitial content (oxygen, carbon, nitrogen, hydrogen) of less than or equal to 500 ppm, based on the total weight of the refractory metal plate. More preferably, the interstitial content of the refractory metal plate may be less than 400 ppm, less than 300 ppm or less than 200 ppm. In terms of ranges, the interstitial content may be from greater than 0 to 500 ppm, e.g., from 10 to 500 ppm, or from 100 to 400 ppm. In one embodiment, the refractory metal plate may have an interstitial content of less than 9 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) or equal to 500 ppm, based on the total weight of the refractory metal plate. More preferably, the interstitial content of the refractory metal plate may be less than 400 ppm, less than 300 ppm or less than 200 ppm. For embodiments where the refractory metal plate is made from a powder process, the refractory metal plate may have an interstitial content of less than or equal to 1000 ppm, based on the total weight of the refractory metal plate, e.g., less than 950 ppm, less than 750 ppm, less than 700 ppm, less than 500 ppm, less than 400 ppm, less than 350 ppm. In terms of ranges, the interstitial content of refractory metal plates made from a powder process may be from greater than 0 to 1000 ppm, e.g., from 10 to 1000 ppm, from 50 to 950 ppm, or from 100 to 600 ppm or from 100 to 500 ppm. A scavenger metal such as magnesium may be used to reduce the oxygen when processing powders.

[0038] As shown in FIG.1, there is disclosed a sputtering target 100 comprising a refractory metal plate 102 and a backing plate 104. In one embodiment, the backing plate 104 is bonded to the refractory metal plate 102, using diffusion-bonding, brazing, welding, soldering, brazing, mechanical fastening, epoxy bonding, friction welding, or explosion bonding. In some embodiments there may be an interlayer (not shown) for bonding the backing plate 104 and refractory metal plate 102. A non-bonded backing plate may also be used in some embodiments.

[0039] The refractory metal plate 102 may be etched away during the deposition process, which may undesirably expose the backing plate 104. The exposure of the backing plate 104 may result in contamination. To achieve sufficient deposition of the material, the embodiments seek to provide a refractory metal plate with sputtering deposition factor of less than 1. As used herein, deposition rate or sputtering rate refers to the number of metal atoms sputtered onto the substrate per impinging sputter gas, such as argon ion.

[0040] While the rate of sputtering from a grain in the target material may depend on the orientation of the crystal planes of that grain relative to the surface, the grains are small such that the orientation of one grain is not determinative. Rather, the texture of an area in target material can have a significant effect. In general, the texture of the refractory metal plate 102 may be uniform.

[0041] Uniformity of film thickness is of importance. In integrated circuits, several hundred of which are created simultaneously on a silicon wafer, for example, too thin a film at one point will not provide an adequate diffusion barrier, and too thick a film at another point will block a via or trench, or, if in an area from which it should be removed in a later step, will not be 10 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) removable. If the thickness of the film deposited is not within the range specified by the designer, the device will not be fit for service, and the total cost of manufacture up to the point of test is lost, since no repair or rework is normally possible.

[0042] Although a rotary configuration is shown in FIG.1, the sputtering target may have other configuration without departing from the embodiments described herein. In some embodiments, the sputtering target may have a square configuration, rectangle configuration, round configuration, tubular configuration, or rotary configuration. The sputtering targets described herein may be used for large scale targets and small scale targets. By way of example, larger scale targets may be sized such that they are capable of sputtering generally uniformly onto a wafer or other substrate having a diameter or largest dimension of at least about 200 mm, at least about 300 mm or even at least about 450 mm. Examples of such target bodies may be generally circular or rectangular plate structures having a diameter (or largest dimension) that exceeds about 0.2 meters, about 0.3 meters, or even about 0.4 meters.

[0043] In one embodiment, the configuration of the backing plate 104 may be similar to the refractory metal plate 102. It is also contemplated that the backing plate 104 may have a slightly larger dimension than the refractory metal plate 102. FIG.1 illustrates a rotary configuration for the backing plate 104 have a larger radius than the refractory metal plate 102 with a similar thickness. Other embodiments may include sputtering targets where the backing plate 104 and refractory metal plate 102 have different thickness.

[0044] The sputtering target according to the descriptions herein may permit the bonding of multiple refractory metal plates to one backing plate, i.e., the plates optionally may include at least two consolidated preformed blocks that are joined together to define the resulting refractory metal plate. This may allow greater output of the sputtering material. If a multiblock assembly is employed, two or more of the resulting consolidated masses may be joined together to form a body by hot isostatically pressing two or more blocks (e.g., while encapsulated in a suitable hot isostatic pressing container). The two or more blocks may be joined together in the presence or the absence of any powder, foil, tile, or other added material within the space between adjoining blocks.

[0045] The crystallographic texture of the sputtering target may be measured by EBSD, as described herein, for analyzing grains having a major direction (e.g., axis) falling within 15° of normal to the surface of the analyzed body. 11 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446)

[0046] The sputtering target may comprise a refractory metal plate comprising a refractory metal and in particular tantalum or tantalum alloy. In one embodiment, the tantalum or tantalum alloy has a purity of 3N5 (99.95 wt%) or greater, e.g., a purity of 4N (99.99 wt%) or greater or more preferably a purity of 5N (99.999 wt%) or greater. In some embodiments, the tantalum alloy may comprise niobium, iron, cobalt, aluminum, copper, molybdenum, tungsten, titanium or alloys or mixtures thereof. For purposes of the present invention, the purity of the tantalum or tantalum alloy is determined based on the total metals, not including any interstitial impurities (C, O, N, H).

[0047] In one embodiment, the refractory metal plate contains high purity tantalum that permits the refractory metal plate to have a density in the range from 15.4 g / cm3to 16.7 g / cm3, e.g., from 15.9 g / cm3to 16.7 g / cm3, or from 16.4 g / cm3to 16.7 g / cm3. Although the backing plate may provide structural integrity, the refractory metal plate may also be sufficiently strong so that it withstands, without fracture, routine stresses encountered during subsequent assembly operations (e.g., a three point straightening assembly operation, a creep flattening operation, or some other operation during which the body is subjected to application of a stress).

[0048] The refractory metal plate may be produced using a powder or billet using thermomechanical processing steps. Thermomechanical processes may use forging, annealing, rolling, heat-treating, and other finishing processes. In one embodiment, the process may use forging to break up the coarse structure of the ingot to form a billet with a uniform grain size. Prior to rolling, the process uses upset / forge-back / anneal sequences to reduce in texture banding severity. In one embodiment, there is at least three or more sequences prior to rolling. In one embodiment, the method of rolling a metal plate may comprise the step of applying shear to the mid-thickness of the metal plate. The rolling may be done using a titled entry into the roll or an asymmetrical rolling. The process may use an annealing step after rolling to achieve substantially full recrystallization. Substantially full “recrystallization,” as used herein, is a term of art, known to those skilled in the art of metallurgy, and refers to a plate having at least 85%, 90%, 95%, 96%, 97%, 98%, 99%, 99.5%, or higher recrystallization. Typically, the amount of recrystallization is determined after the final annealing step, when a sample is taken from the edge of the plate and examined microscopically.

[0049] In one embodiment, a tantalum powder billet that may be cold isostatically pressed, then hot isostatically pressed and then subjected to thermomechanical processing (i.e., a series of 12 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) cross-rolls). Following the step of hot isostatic pressing there may be one or more steps of machining and / or surface finishing of the refractory metal plate. For example, surface material may be removed by grinding and / or polishing. One or more structural features may be machined as well (e.g., one or more features for fixturing, for receiving an O-ring in a backing plate for high vacuum applications, or otherwise). To produce the sputtering target, the teachings herein also may attach a backing plate to the refractory metal plate.

[0050] Tantalum powder may also be used. A sputtering target having a refractory metal plate in accordance with the present teachings may be prepared by consolidating the powders of the present teachings. Consolidating may be by one or any combination of sintering, hot isostatic pressing, hot extruding, or otherwise. A mass of powders can be cold isostatically pressed by applying a suitable pressure (e.g., to an initial state at a pressure of about 220 MPa) to achieve a density ranging from about 82 to about 88% of theoretical density. The cold isostatic pressed powders, while within a container, may be hot isostatically pressed under suitable temperature and pressure conditions and for suitable time (e.g., at a temperature of about 1250 degrees C., a pressure of about 207 MPa for a period of time such as about 6 hours) to achieve a density near theoretical density (e.g., at least 98% of theoretical density). The resulting hot isostatically pressed body is removed from the container and can be processed (e.g., by cutting and / or machining to final dimensions).

[0051] In one embodiment, the method for making a refractory metal plate includes providing a powder of tantalum, or other refractory metal, having a purity of at least 99.95 wt%, e.g., at least 99.99 wt%, or still more preferably at least 99.995 wt%, and having an oxygen content below 75 ppm, e.g., below 60 ppm or below 50 ppm, and / or having a maximum magnesium content below 10 ppm (or even 5 ppm). The powder may have a particle size that is below 1000 μm, e.g., below 850 μm, below 650 μm, below 500 μm, below 350 μm or even below 250 μm. For instance, about 95 percent, about 85 percent, about 75 percent by weight of the total particles may have a particle size that is at least 10 μm, e.g., at least 40 μm, at least 65 μm or at least 90 μm. About 95 percent of the total particles may have a particle size that is below 1000 μm, e.g., below 850 μm, below 650 μm, below 500 μm, below 350 μm or below 250 μm. In one embodiment, the powders contain no particles in the powder exceed 1000 μm.

[0052] In one embodiment, 25 to 65 percent by weight of the particles, e.g., 29 to 56 percent or even 35 to 47 percent, in the at least one mass of metal powder may have a particle size that is 13 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) larger than 65 μm, e.g. larger than 150 μm, larger than 250 μm, larger than 500 μm, larger than 650 μm or larger than 850 μm, but below about 1000 μm. In accordance, the embodiments described herein may use powders having 25 to 65 percent by weight of the particles, e.g., 29 to 56 percent or even 35 to 47 percent, with a particle size that is less than 1000 μm, e.g., less than 850 μm, less than 650 μm, less than 500 μm, less than 350 μm, or less than 250 μm, but above about 10 μm. To effectively consolidated mass the process may use a powder that contains at least 10 percent by weight of particles having a particle size greater than 150 μm results in an effectively consolidated mass (e.g., as a result of hot isostatic pressing). Preferably, the process may use a powder that contains at least 20 percent by weight of particles having a particle size greater than 150 μm results, e.g., at least 30 percent, at least 40 percent, or at least 50 percent.

[0053] Unless otherwise stated, powder particle sizes are determined by screen analysis in accordance with ASTM B214-07(2011). Further, unless otherwise stated, particle sizes refer to pre-consolidation sizes.

[0054] The powder may be isostatically pressed to define a body at a temperature that is at or below 1400° C., e.g., at or below 1325° C., or at or below 1250° C. It is possible that pressing may be at lower temperatures (e.g., at or below 1100° C. (e.g., at or below 1080° C. or at or below 1000° C.)). Pressing may be at a pressure in the range from 100 MPa to 300 MPa, e.g., about 170 MPa to about 250 MPa.

[0055] Pressing or another mode of consolidating may also be done under such conditions for a period of time sufficient to obtain a crystallographic texture (as measured by electron backscatter detection (“EBSD”), as described herein. By way of example, without limitation, the material may be pressed to form a disk-shaped body that will be subject to bombardment during the sputtering process.

[0056] In one embodiment, the rolling process may contribute plane orientation of the target material. The amount and distribution of strain that is introduced from the rolling process may be controlled by several factors including, asymmetric rolling, the diameter of the rolling mill roll, rolling speed, and rolling reduction. In one embodiment, the process is not necessarily limited provided that the desired plane orientation may be achieved.

[0057] The sputtering targets comprising tantalum or tantalum alloy are particular suited for forming thin films for optical fibers, semiconductor wafers, and integrated circuits. It also is contemplated that thin films result that are used in any of a number of electronic components or 14 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) devices (e.g., as a layer, such as a barrier layer, an electrode layer, as part of a semiconductor, as part of an integrated circuit, or otherwise), such as one or more of a television, a video display, a smartphone, a tablet computer, a personal digital assistant, a navigation device, a sensor, a portable entertainment device (e.g., video players, music players, etc.), or even a photovoltaic device.

[0058] The thin film for semiconductor application is created by using the method according to the previous embodiments, where variation in film thickness uniformity (percent non-uniformity) may be 8% or less, e.g., 7.5% or less, 7% or less, 6.5% or less, 6% or less, 5.5% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, or 3% or less. In one embodiment, the variation in sheet resistance, within wafers, and between wafers may be 8% or less, e.g., 7.5% or less, 7% or less, 6.5% or less, 6% or less, 5.5% or less, 5% or less, 4.5% or less, 4% or less, 3.5% or less, or 3% or less.

[0059] In one embodiment, sputtering using the refractory metal plate herein may include one or more steps of sputtering to depths that are substantially the entire thickness of the refractory metal plate, e.g., to a depth that is at least 80%, 90%, or even 95% the thickness of the refractory metal plate. The sputtering may be to a depth that does not include the backing plate.

[0060] The present disclosure depicts sputtering targets made from the refractory metal plates, thin films produced from such sputtering targets, and sputtering methods utilizing the sputtering targets. In one embodiment, the sputter deposition may be a physical vapor deposition method to form thin films. In forming the thin films, the material from the sputter target may be exposed to energetic particles from a plasma or gas, such as argon, krypton, xenon, neon, nitrogen, or mixtures thereof. The exposure to the energetic particles from the of plasma or gas cause particles from the sputter target to be ejected onto a substrate, such as a silicon wafer, to form a thin film. The sputtering target is placed in a deposition chamber to position the target material towards the substrate.

[0061] Uniformity of film thickness is of major importance. In integrated circuits, several hundred of which are created simultaneously on a silicon wafer, for example, too thin a film at one point will not provide an adequate diffusion barrier, and too thick a film at another point will block a via or trench, or, if in an area from which it should be removed in a later step, will not be removable. If the thickness of the film deposited is not within the range specified by the 15 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) designer, the device will not be fit for service, and the total cost of manufacture up to the point of test is lost, since no repair or rework is normally possible.

[0062] The present disclosure may be understood more readily by reference to the following detailed description of desired embodiments and the examples included therein. In the following specification and the claims which follow, reference will be made to a number of terms which shall be defined to have the following meanings.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Preferred methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0064] The singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0065] 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 that require the presence of the named ingredients / steps and permit the presence of other ingredients / steps. However, such description should be construed as also describing compositions or methods as “consisting of” and “consisting essentially of” the enumerated ingredients / steps, which allows the presence of only the named ingredients / steps, along with any impurities that might result therefrom, and excludes other ingredients / steps.

[0066] Numerical values in the specification and claims of this application, as they relate to polymers or polymer compositions, reflect average values for a composition that may contain individual polymers of different characteristics. The numerical values disclosed herein 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 16 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0067] All ranges disclosed herein are inclusive of the recited endpoint and independently combinable (for example, the range of “from 1 micron to 40 microns” is inclusive of the endpoints, 1 micron and 40 microns, and all the intermediate values). The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value; they are sufficiently imprecise to include values approximating these ranges and / or values.

[0068] As used herein, approximating language may be applied to modify any quantitative representation that may vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about” and “substantially,” may not be limited to the precise value specified, in some cases. The modifier “about” should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4”. The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean from 0.9-1.1.

[0069] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is explicitly contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the number 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are explicitly contemplated.

[0070] The present disclosure has been described with reference to exemplary embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the present disclosure 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.

[0071] Embodiment 1 is a refractory metal plate comprising a center, a thickness, an edge, a top surface and a bottom surface. The refractory metal plate may be characterized by a sputtering deviation factor based on <100> texture, <110> texture, and <111> texture of less than 1, and at least one impurity element in an amount up to 500 ppm, wherein the metal plate has a grain size 17 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) greater than or equal to 10 μm, and wherein the thickness is less than or equal to 1.6 cm as measured from the top surface to the bottom surface.

[0072] Embodiment 2 is the refractory metal plate of embodiment 1 wherein sputtering deviation factor is less than 0.6.

[0073] Embodiment 3 is the refractory metal plate of any one of embodiments 1 or 2, wherein the refractory metal plate comprises at least one refractory metal comprising tantalum, scandium, niobium, titanium, hafnium, ruthenium, or rhenium.

[0074] Embodiment 4 is the refractory metal plate of any one of embodiments 1-3, wherein the at least one impurity element comprises silicon, phosphorus, boron, yttrium, ion, nickel, chromium, tungsten, molybdenum, niobium, copper, vanadium, hafnium, titanium, ruthenium, or rhenium, provided that the at least one impurity element is different from the at least one refractory metal.

[0075] Embodiment 5 is the refractory metal plate of any one of embodiments 1-4, wherein the refractory metal plate is at least 99.95% pure or more.

[0076] Embodiment 6 is the refractory metal plate of any one of embodiments 1-5, wherein the at least one impurity element is in an amount up to 100 ppm.

[0077] Embodiment 7 is the refractory metal plate of any one of embodiments 1-6, wherein the at least one impurity element is in an amount up to 50 ppm.

[0078] Embodiment 8 is the refractory metal plate of any one of embodiments 1-7, wherein the top surface contains less than 25% of the total amount of the at least one impurity element.

[0079] Embodiment 9 is the refractory metal plate of any one of embodiments 1-8, wherein the bottom surface contains less than 25% of the total amount of the at least one impurity element.

[0080] Embodiment 10 is the refractory metal plate of any one of embodiments 1-9, wherein the thickness is from 0.25 cm to 1.5 cm.

[0081] Embodiment 11 is the refractory metal plate of any one of embodiments 1-10, wherein the grain size of the metal plate is from 10 μm to 120 μm.

[0082] Embodiment 12 is the refractory metal plate of any one of embodiments 1-11, wherein the area fraction total of the <100> texture, the <110> texture, and the <111> texture, represents 40% or more of the total grains. 18 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446)

[0083] Embodiment 13 is the refractory metal plate of any one of embodiments 1-12, wherein the area fraction total of the <100> texture, the <110> texture, and the <111> texture, represents from 40% to 90% of the total grains.

[0084] Embodiment 14 is the refractory metal plate of any one of embodiments 1-13, wherein the area fraction total of the <100> texture, the <110> texture, and the <111> texture, represents from 40% to 60% of the total grains.

[0085] Embodiment 15 is the refractory metal plate of any one of embodiments 1-14, wherein the area fraction of the <100> texture is greater than the area fraction of the <110> texture or the <111> texture.

[0086] Embodiment 16 is the refractory metal plate of any one of embodiments 1-15, wherein the area fraction of the <110> texture is 20% or less based on the total grains.

[0087] Embodiment 17 is the refractory metal plate of any one of embodiments 1-16, wherein the grain size is stable up to temperatures of 1260°C.

[0088] Embodiment 18 is a method for identifying nonuniformity in a refractory metal plate comprising calculating a reference sputtering rate by the steps of: calculating sputtering yield within 15° of an orientation of a <100> texture, a <110> texture, and a <111> texture for a reference plate; measuring an area fraction of an <100> texture, <110> texture, and <111> texture using a cross-section of the reference plate in the normal direction; normalizing the area fraction of the reference plate based on the orientation of the <100> texture, the <110> texture, and the <111> texture; and determining a reference sputtering rate based on at least the normalized area fraction of the reference plate; measuring an area fraction of an <100> texture, <110> texture, and <111> texture using a cross-section of the refractory metal plate in the normal direction; normalizing the area fraction of the refractory metal plate based on the orientation of the <100> texture, the <110> texture, and the <111> texture; determining a sample sputtering rate based on at least the normalized area fraction of the refractory metal plate; and comparing the reference sputtering rate with the sample sputtering rate to identify the refractory metal plate is uniform when less than 1.

[0089] Embodiment 19 is the process of embodiment 18, wherein the comparing the reference sputtering rate with the sample sputtering rate to identify the refractory metal plate is uniform when less than 0.6.

[0090] The present disclosure is further understood by the following non-limiting examples. 19 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) Examples Example 1

[0091] FIG.2 is a graph of a refractory metal plate of tantalum (purity > 99.95%) having a thickness of 12.7 mm. The total impurities in the refractory metal plate were contained in an amount of less 100 ppm. The impurities included Si, Ti, Cr, Fe, Ni, Cu, Nb, W, and Mo. The metal plate had a grain size of greater than 60 microns. The area of the <100> is the darkest color line on the graph (black). The area of the <111> texture is the lightest color line on the graph (light grey). The area of the <110> texture is the medium color line on the graph (dark grey). The sputtering deposition factor in FIG.2 is 0.48. Comparative Example A

[0092] FIG.3 is a graph of a refractory metal plate of tantalum (purity > 99.95%) having the same thickness as Example 1. Similar to Example 1, the total impurities in the refractory metal plate were contained in an amount of less 100 ppm. The metal plate had a grain size of greater than 40 microns. The area of the <100> is the darkest color line on the graph (black). The area of the <111> texture is the lightest color line on the graph (light grey). Note that in FIG.3, the <111> texture has a large peak which contributes to the non-uniformity. The area of the <110> texture is the medium color line on the graph (dark grey). The sputtering deposition factor in FIG.3 is 1.23.

[0093] 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 be appreciated 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. 20 LEGAL\73766982\1

Claims

Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) What is Claimed is:

1. A refractory metal plate comprising: a center, a thickness, an edge, a top surface and a bottom surface, the refractory metal plate characterized by: a sputtering deviation factor based on <100> texture, <110> texture, and <111> texture of less than 1; and at least one impurity element in an amount up to 500 ppm; wherein the metal plate has a grain size greater than or equal to 10 μm; and wherein the thickness is less than or equal to 1.6 cm as measured from the top surface to the bottom surface.

2. The refractory metal plate of claim 1, wherein sputtering deviation factor is less than 0.

6.

3. The refractory metal plate of any one of claims 1 or 2, wherein the refractory metal plate comprises at least one refractory metal comprising tantalum, scandium, niobium, titanium, hafnium, ruthenium, or rhenium.

4. The refractory metal plate of any one of claims 1-3, wherein the at least one impurity element comprises silicon, phosphorus, boron, yttrium, ion, nickel, chromium, tungsten, molybdenum, niobium, copper, vanadium, hafnium, titanium, ruthenium, or rhenium, provided that the at least one impurity element is different from the at least one refractory metal.

5. The refractory metal plate of any one of claims 1-4, wherein the refractory metal plate is at least 99.95% pure or more.

6. The refractory metal plate of any one of claims 1-5, wherein the at least one impurity element is in an amount up to 100 ppm. 21 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) 7. The refractory metal plate of any one of claims 1-6, wherein the at least one impurity element is in an amount up to 50 ppm.

8. The refractory metal plate of any one of claims 1-7, wherein the top surface contains less than 25% of the total amount of the at least one impurity element.

9. The refractory metal plate of any one of claims 1-8, wherein the bottom surface contains less than 25% of the total amount of the at least one impurity element.

10. The refractory metal plate of any one of claims 1-9, wherein the thickness is from 0.25 cm to 1.5 cm.

11. The refractory metal plate of any one of claims 1-10, wherein the grain size of the metal plate is from 10 μm to 120 μm.

12. The refractory metal plate of any one of claims 1-11, wherein the area fraction total of the <100> texture, the <110> texture, and the <111> texture, represents 40% or more of the total grains.

13. The refractory metal plate of any one of claims 1-12, wherein the area fraction total of the <100> texture, the <110> texture, and the <111> texture, represents from 40% to 90% of the total grains.

14. The refractory metal plate of any one of claims 1-13, wherein the area fraction total of the <100> texture, the <110> texture, and the <111> texture, represents from 40% to 60% of the total grains.

15. The refractory metal plate of any one of claims 1-14, wherein the area fraction of the <100> texture is greater than the area fraction of the <110> texture or the <111> texture.

16. The refractory metal plate of any one of claims 1-15, wherein the area fraction of the <110> texture is 20% or less based on the total grains. 22 LEGAL\73766982\1Materion Ref. AMG-1117-PCT; 2024-00211 Attorney Docket No. A18202-MTRN (00624446) 17. The refractory metal plate of any one of claims 1-16, wherein the grain size is stable up to temperatures of 1260°C. 23 LEGAL\73766982\1

Images