Metals and metal alloys for sputtering targets

Abstract

A sputtering target comprising a target plate comprising high purity tantalum or tantalum alloy and a backing plate. The portion of the target plate being adjacent to the backing plate contains a different texture than the remaining sputtering portion of the target plate. In one embodiment, the volume percentage of <110> texture of the target plate is from 2% to 20% through thickness as determined by electron backscatter diffraction (EBSD), while the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 8%.

Description

Metals and Metal Alloys for Sputtering TargetsPRIORTY CLAIM

[0001] The application claims priority to U.S. Provisional Application No. 63 / 511 ,058 filed on June 29, 2023, which is fully incorporated by reference herein.FIELD

[0002] The present disclosure relates to metals and metal alloys target plates that are suitable for sputtering targets. In particular, the metals and metal alloys target plates produce sputtering targets that have improved deposition performance and improved texture through thickness.BACKGROUND

[0003] Sputtering processes are employed to deposit thin films from a target onto substrates, such as a silicon wafer, to manufacture any of 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.

[0004] 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 tantalum are processed from an ingot obtained by subjecting a tantalum raw material to melting and casting, which may include thermosmechanically processes such as forging, annealing, rolling, heat-treating, and otherfinishing processes.

[0005] 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 isdesired to employ powders that have a low content of undesired metallic impurities, and / or a low content of oxygen.

[0006] 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.

[0007] 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 pm, with at least about 10 percent by weight of particles having a particle size greater than about 150 pm (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 pm), for defining at least a portion of a sputtering target body, having an essentially theoretical random and substantially uniform crystallographic texture.

[0008] There is therefore a need in the art for sputtering targets that have improved sputtering rates, have reduced contamination, and reduce unpredictability of sputter rate and direction. This disclosure addresses those needs.SUMMARY

[0009] In general, the disclosure relates to a sputtering target comprising a target plate comprising tantalum or tantalum alloy having a high purity having an unique plane orientation. Usingthe sputtering target can improve production of thin films during sputtering.

[0010] In one aspect there is provided a sputtering target comprising a target plate comprising tantalum or tantalum alloy having a purity of 3N5 (99.95 wt%) or greater, wherein the purity is determined based on the total metals, not including any interstitial impurities, wherein the thickness is from 0.2 mm to 11 mm, and an average grain size inthe range from 10 to 120 microns, wherein the volume percentage of <110> texture of the target plate is from 2% to 20% through thickness as determined by electron backscatter diffraction (EBSD); and a backing plate, wherein the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 8%, and more preferably less than 7%. In one embodiment, the tantalum or tantalum alloy has a purity of 4N (99.99 wt.%) or greater, based on the total metals. The other metals in the target plate may include niobium, iron, cobalt, aluminum, copper, molybdenum, tungsten, titanium or alloys or mixtures thereof. The interstitial content (C, O, N, H) of the target plate of less than or equal to 500 ppm, based on the total weight of the target plate, and for process that use powder, less than or equal to 1000 ppm.

[0011] In one embodiment, the volume percentage of <100> texture of the target plate is from 20% to 40% through thickness, the volume percentage of <110> texture of the target plate is from 2% to 20% through thickness, and the volume percentage of <111 > texture of the target plate is from 5% to 25% through thickness, as determined by EBSD. In a preferred embodiment, the <110> texture through thickness is stable in the upper portion of the target plate, i.e. the sputtering portion to be bombarded. In one embodiment, the target plate may have a thickness ranging from 0.2 mm to 11 mm.

[0012] In one aspect there is provided a sputtering target comprising a target plate comprising tantalum or tantalum alloy having a purity from 3N5 (99.95 wt%) or greater, wherein the purity is determined based on the total metals, not including any interstitial impurities, wherein the thickness is from 0.2 mm to 11 mm, and an average grain size in the range from 10 to 120 microns, wherein the sum of the volume percentage of the <100> and <110> texture is from 20% to 55% through thickness as determined by electron backscatter diffraction (EBSD); and a backing plate, wherein the volume percentage of the <100> texture in the target plate adjacent to the backing plate is greater than the volume percentage of the <110> texture adjacent to the backing plate. In one embodiment, the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 8%, and more preferably less than 7%. In one embodiment, the tantalum or tantalum alloy has a purity of 4N (99.99 wt.%) or greater, based on the total metals. Theother metals in the target plate may include niobium, iron, cobalt, aluminum, copper, molybdenum, tungsten, titanium or alloys or mixtures thereof. The interstitial content (C, O, N, H) of the target plate of less than or equal to 500 ppm, based on the total weight of the target plate, and for process that use powder, less than or equal to 1000 ppm.

[0013] These and other non-limiting characteristics are more particularly described below.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The invention is further illustrated by the following drawings in which:

[0015] FIG. 1 is an illustration of a sputtering target having a target plate with a sputtering portion and adjacent portion in accordance with embodiments disclosed herein; and

[0016] FIGS. 2A, 2B, 2C, 2D, 2E, and 2F are grain maps of a tantalum target plate from the center to the edge in accordance with the example.

[0017] FIG. 3 is an average texture graph of the tantalum target plate in accordance with the example.DETAILED DESCRIPTION

[0018] 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.

[0019] The present disclosure depicts sputtering targets, thin films produced from such sputtering targets, and sputtering methods utilizingthe 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 chamberto position the target material towards the substrate.

[0020] As shown in FIG. 1 , there is disclosed a sputtering target 100 comprising a target plate 102 and a backing plate 104. In one embodiment, the backing plate 104 is bonded to the target 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 target plate 102. Non-bonded backing plates may also be used in some embodiments. The backing plate 104 may comprise copper, aluminum, titanium molybdenum, zinc, or combinations or alloys thereof. In one embodiment, the backing plate 104 may comprise a copper-zinc alloy or an aluminum alloy of the 2000, 6000 or 7000 series. Preferably, the backing plate 104 is a different material than the target plate. The backing plate is configured to hold the target plate 102 in a position suitable for deposition. In addition, the backing plate 104 may provide mechanical strength, electrical conductivity, and thermal conductivity to the sputter target. Heat treatment may be used to provide the backing plate 104 with a higher mechanical strength than the target plate 102.

[0021] The target plate 102 comprises a sputtering portion 106 and an adjacent portion 108. The sputtering portion 106 comprises the material that is deposited during sputtering. The target plate 102 may be etched away duringthe deposition process, which may undesirably expose the backing plate 104. The exposure of the backing plate 104 may result in contamination. To prevent such exposure, the target plate 102 contains the sputtering portion 106 which is preferably etched away. Once the sputtering portion 106 is etched away, the adjacent portion 108 may be exposed. This is more desirable to expose the adjacent portion 108 than the backing plate 104 leading to less contamination. To achieve sufficient deposition of the material, the embodiments seekto provide a target plate with an enriched sputtering portion. Although a substantial portion of the adjacent portion 108 may be left unused, the increase in deposition rates and reduction in contamination is beneficial. 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.

[0022] While the rate of sputteringfrom 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 sputtering portion 106 may be uniform, but is different from the adjacent portion 108. Thus, considered as a whole the target plate 102 lacks a uniform structure, but is able to provide improve sputtering performance.

[0023] 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 ortrench, 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 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. Accordingly, the sputtering portion 106 may demonstrate an uniform texture that is different from the texture of the target plate 102 as a whole.

[0024] Generally it is preferred that the sputtering portion 106 is larger in relative thickness through the target plate than the adjacent portion 108. This results in better material utilization. In one embodiment, the sputtering portion 106 has a substantially uniform thickness from the centerto the edge. In terms of relative thickness, the sputtering portion 106 may comprise 80% or more of the thickness of the target plate, e.g., 85% or more, or more preferably, 90% or more. In terms of ranges, the sputtering portion may be from 80% to 95% of the thickness of the target plate, e.g., from 80% to 93%, from 82% to 92% or from 85% to 90%. The technical benefit of having a substantial portion of the target plate 102 comprise the sputtering portion 106 affords improved sputtering rates while avoiding through thickness variations that could result in different sputtering rates. Particle generation and / or other adverse conditions that could prematurely shorten the life of a sputtering target may also be avoided by using the sputtering target described herein.

[0025] The adjacent portion 108 is a portion of the target plate 102 that is adjacent to the backing plate 104 and is typically not deposited during sputtering. In terms of relative thickness, the adjacent portion 108 may comprise 20% or less of the thickness of the target plate, e.g., 15% or less, or more preferably, 10% or less. In terms of ranges the adjacent portion 108 may be from 5% to 20% of the thickness of the target plate, e.g., form 7% to 18% or from 10% to 15%. As described herein, the deposition is improved due to the increased volume percentage of the <110> texture in the target plate 102 while the adjacent portion 108 to the backing plate 104 contains a lower volume percentage of the <110> texture than the target plate 102 as a whole or the volume percentage of the <110> texture in the sputtering portion 106 of the target plate 102.

[0026] In one embodiment, the thickness of the target plate may be from 0.2 mm to 11 mm, e.g., from 0.25 mm to 10 mm, from 0.3 mm to 9 mm, from 0.3 mm to 8 mm, from 0.5 mm to 7.5 mm, from 1 mm to 7 mm, or from 1 mm to 6.5 mm. Accordingly, the sputtering portion 106 may have a thickness from 0.6 mm to 10.5 mm, e.g., from 0.75 mm to 10 mm orfrom 1 mm to 6.5 mm. The smaller adjacent portion 108 may have a reduced thickness in the range from 0.1 mm to 7 mm, e.g., from 0.2 mm to 6.75 mm, from 0.2 mm to 6.5 mm, orfrom 0.2 mm to 6.4 mm.

[0027] Although a rotary configuration is shown in FIG. 1 , the sputtering target may have other configuration without departingfrom 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. Byway 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, e.g., exceeds about 0.3 meters, or even exceeds about 0.4 meters.

[0028] In one embodiment, the configuration of the backing plate 104 may be similar to the target plate 102. It is also contemplated that the backing plate 104 may have a slightly larger dimension than the target plate 102. FIG. 1 illustrates a rotary configuration for the backing plate 104 have a larger radius than the target plate 102 with a similar thickness. Other embodiments may include sputtering targets where the backing plate 104 and target plate 102 have different thickness.

[0029] The sputtering target according to the descriptions herein may permit the bonding of multiple target plates to one backing plate, i.e. the target body optionally may include at least two consolidated preformed blocks that are joined together to define the resulting target plate. This may allow greater output of target materials. If a multiblock assembly is employed, two or more of the resulting consolidated masses may be joined together to form a target 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.

[0030] 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. Mappingthree grain orientations, each map shows the grains which have particular crystallographic directions

[0031] In one embodiment, there is provided a sputtering target comprising a target plate comprising tantalum or tantalum alloy having a high purity, a small grain size, and the volume percentage of <110> texture of the target plate is from 2% to 20% through thickness as determined by electron backscatter diffraction (EBSD), and a backing plate, wherein the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 8%. In one embodiment, a thin film may be formed using such a sputtering target.

[0032] In one embodiment, there is provided a sputtering target comprising a target plate comprising tantalum or tantalum alloy having a high purity, a small grain size, and wherein the sum of the volume percentage of the <100> and <110> texture is from 20% to 55%through thickness as determined by electron backscatter diffraction (EBSD), and a backing plate, wherein the volume percentage of the <100> texture in the target plate adjacent to the backing plate is greater than the volume percentage of the <110> texture adjacent to the backing plate. In one embodiment, the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 8%. Preferably, the volume percentage the <100> texture may be greater than the <110> texture in the target plate as a whole or in the sputtering portion of the target plate. In one embodiment, a thin film may be formed using such a sputtering target.

[0033] Broadly stated, the sputtering targets exhibit a structure having a crystallographic texture that is heterogeneous between the sputtering and adjacent portions. In one embodiment, the crystallographic texture may be generally uniform throughout each portion of the target plate, and preferably generally uniform throughout the sputtering portion of the target plate. In one embodiment, the sputtering targets may have a crystallographic texture that is devoid of textual banding, preferably a sputtering target having an average through-thickness gradient that has an absolute value below about 6% / mm for the <100> and <111 > textures. In one embodiment, the sputtering target may have an average through-thickness gradient that has an absolute value below about 5% / mm, e.g., 4% / mm, 3% / mm, 2% / mm or even 1 % / mm.

[0034] The sputtering target comprising a target plate having a center, a thickness, an edge, a top surface and a bottom surface. The bottom surface comprises the adjacent portion and may be bonded to a backing plate. The top surface comprises the sputtering portion is exposed during the sputtering process. In one embodiment, the crystallographic texture components <100> and <111 > which may substantially uniform throughout the target plate, while texture component <110> is less uniform. This allows the texture component <110> to be concentrated in the sputtering portion that improves sputtering performance and film uniformity. The target produced with heterogeneity, i.e. difference in the <110> texture in the sputtering and adjacent portion, surprisingly and unexpected improves the sputtering performance and film uniformity.

[0035] In one embodiment, the <110> texture through thickness may be stable in the upper portion, i.e. sputtering portion, of the target plate. Stability of the <110> texture contributes to improved sputtering rates. In one embodiment, the target plate has from 2% to 20% by volume of the <110> texture through thickness as determined by EBSD. Preferably, the target plate has from 3% to 18% by volume <110> through thickness as determined by EBSD, e.g., more preferably from 3% to 15% by volume, from 3% to 12% by volume, or from 3% to 10% by volume. When the volume percentage of the <110> texture is less than 3% by volume the stability of the <110> texture decreases. In one embodiment the sputtering portion of the target plate has from 2% to 20% by volume of the <110> texture through thickness as determined by EBSD, e.g., 3% to 20% by volume, 3% to 18% by volume, from 3% to 15% by volume, from 3% to 12% by volume, or from 3% to 10% by volume.

[0036] The <110> texture in the portion of the target plate that is adjacent to the backing plate, referred to as the adjacent portion, may be lowered than the sputtering portion. The adjacent portion is preferably not etched duringthe sputtering process. Accordingly, it is desirable thatthis portion contain less of the <110> texture. In one embodiment, the volume percentage of the <110> texture in the target plate adjacent to the backing plate may be less than 8% through thickness, e.g., less than 7%, less than 6%, less than 5%, less than 4% or less than 3%. In terms of ranges the volume percentage of the <110> texture in the target plate adjacent to the backing plate may from greater than 0% to less than 8%, e.g., from 0.01% to less than 8%, from 0.1% to 7.5%, from 0.1% to 7.0%, from 0.5% to 6.5% or from 1.5% to 6.2%.

[0037] In one embodiment, the volume percentage of <100> texture of the target plate may be from 20% to 45% through thickness, e.g. from 20% to 42%, from 20% to 40%, from 25% to 40%, from 25% to 37.5% or from 30% to 37.5%. The volume percentage of <100> texture in the sputtering portion may be similar to the volume percentage of <100> texture in the adjacent portion. In some embodiments, the adjacent portion may be slightly higher in terms of volume percentage of <100> texture as compared with the sputtering portion. The sum of the volume percentage of the <110> texture and <100> texture of the target plate is from 20% to 55% through thickness, e.g., from 23% to 50%, or from 25% to 50%.

[0038] In one embodiment, the volume percentage of <111 > texture of the target plate may be from 5% to 25% through thickness, e.g., from 5% to 23%, from 5% to 20% or from 5% to 18.5%. The volume percentage of <111 > texture in the sputtering portion may be similar to the volume percentage of <111 > texture in the adjacent portion. In some embodiments, the adjacent portion may be slightly higher in terms of volume percentage of <111 > texture as compared with the sputtering portion. The sum of the volume percentage of the <110> texture and <111 > texture of the target plate is from 8% to 45% through thickness, e.g., from 10% to 40%, or from 15% to 40%.

[0039] The sputtering target comprise a target plate comprising a refractory metal and in particulartantalum 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 ortantalum alloy is determined based on the total metals, not including any interstitial impurities (C, O, N, H).

[0040] In one embodiment, the target plate contains high purity tantalum that permits the target 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 target 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 target body is subjected to application of a stress).

[0041] In one embodiment, the target plate may have an interstitial content of less than or equal to 500 ppm, based on the total weight of the target plate. More preferably, the interstitial content of the target 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. For embodiments where the targetplate is made from a powder process, the target plate may have an interstitial content of less than or equal to 1000 ppm, based on the total weight of the target 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 target 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.

[0042] The sputtering target comprise a target plate having a reduced grain size. In one embodiment, the target plate may have an average grain size rangingfrom 10 to 120 microns, e.g., from 15 to 120 microns, or from 20 to 120 microns, from 30 to 120 microns, from 40 to 120 microns orfrom 50 to 120 microns. Grain size measurements are made according to ASTME112-12.

[0043] In one embodiment, there may be some grains with smaller sizes than the average size. In particular, the portion of the target that is subjected to bombardment for sputtering may have a reduced grain size. The average grain size may be realized substantially throughout the entirety of the target plate or at least preferably in the sputtering portion. The average grain size and grain size distribution may be substantially uniform throughout the entirety of the target. In one embodiment, a significant portion of the grains may be generally equiaxed. For example, at least about 60%, 70% or more by volume of the grains may be generally equiaxed.

[0044] The target material may be produced using a powder or billet using thermomechanical processing steps. 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 cross-rolls). Following the step of hot isostatic pressing there may be one or more steps of machining and / or surface finishing of the target 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 vacuumapplications, or otherwise). To produce the sputtering target, the teachings herein also may attach a backing plate to the target plate.

[0045] Tantalum powder may also be used. A sputtering target body in accordance with the present teachings may be prepared by consolidatingthe 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 machiningto final dimensions).

[0046] In one embodiment, the method for making a target 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 pm, e.g. below 850 pm, below 650 pm, below 500 pm, below 350 pm or even below 250 pm. 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 pm, e.g. at least 40 pm, at least 65 pm or at least 90 pm. About 95 percent of the total particles may have a particle size that is below 1000 pm, e.g., below 850 pm, below 650 pm, below 500 pm, below 350 pm or below 250 pm. In one embodiment, the powders contains no particles in the powder exceed 1000 pm.

[0047] 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 larger than 65 pm, e.g. larger than 150 pm, larger than 250 pm, largerthan 500 m, larger than 650 m or larger than 850 pm, but below about 1000 pm. 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 pm, e.g., less than 850 pm, less than 650 pm, less than 500 pm, less than 350 pm, or less than 250 pm, but above about 10 pm. 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 pm 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 pm results, e.g., at least 30 percent, at least 40 percent, or at least 50 percent.

[0048] 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.

[0049] The powder may be isostatically pressed to define a target 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.

[0050] 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.

[0051] 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 necessary limited provided that the desired plane orientation may be achieved.

[0052] 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 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.

[0053] 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) is 3% or less, and variation in sheet resistance, within wafers, and between wafers is 3% or less.

[0054] In one embodiment, sputtering using the target plate herein may include one or more steps of sputtering to depths that are substantially the entire thickness of the sputtering portion, e.g., to a depth that is at least 80%, 90%, or even 95% the thickness of the sputtering portion. The sputtering may be to a depth that does not include the adjacent portion or backing plate.

[0055] 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.

[0056] The singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0057] 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.

[0058] 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 experimental error of conventional measurement technique of the type described in the present application to determine the value.

[0059] 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 / orvalues.

[0060] 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.

[0061] 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.

[0062] The present disclosure has been described with reference to exemplary embodiments. Obviously, modifications and alterations will occur to others upon reading and understandingthe preceding detailed description. It is intended that the present disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims orthe 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.

[0063] Embodiment 1 is a sputtering target comprising a target plate comprisingtantalum or tantalum alloy having a purity of 3N5 (99.95 wt%) or greater, wherein the purity is determined based on the total metals, not including any interstitial impurities, wherein the thickness is from 0.2 mm to 11 mm, and an average grain size in the range from 10 to 120 microns, wherein the volume percentage of <110> texture of the target plate is from 2% to 20% through thickness as determined by electron backscatter diffraction (EBSD); and a backing plate, wherein the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 8%.

[0064] Embodiment 2 is the sputtering target of embodiment 1 , wherein the tantalum alloy comprises niobium, iron, cobalt, aluminum, copper, molybdenum, tungsten, titanium or alloys or mixtures thereof.

[0065] Embodiment 3 is the sputtering target of any one of embodiments 1 or 2, wherein the volume percentage of <110> texture of the target plate is from 3% to 20% through thickness as determined by EBSD.

[0066] Embodiment 4 is the sputtering target of any one of embodiments 1 -3, wherein thickness is from 0.25 mm to 10 mm.

[0067] Embodiment 5 is the sputtering target of any one of embodiments 1 -4, wherein the target plate has an interstitial content of less than or equal to 500 ppm, based on the total weight of the target plate.

[0068] Embodiment 6 is the sputtering target of any one of embodiments 1 -5, wherein the target plate has an interstitial content of less than or equal to 1000 ppm, based on the total weight of the target plate.

[0069] Embodiment 7 is the sputtering target of any one of embodiments 1 -6, wherein the tantalum or the tantalum alloy has a purity of 4N (99.99 wt%) or greater.

[0070] Embodiment 8 is the sputtering target of any one of embodiments 1 -7, wherein the tantalum or the tantalum alloy has a purity of 5N (99.999 wt%) or greater.

[0071] Embodiment 9 is the sputtering target of any one of embodiments 1 -8, wherein the average grain size is in the range from 50 to 120 microns.

[0072] Embodiment 10 is the sputtering target of any one of embodiments 1 -9, wherein the volume percentage of the <110> texture is from 3% to 12% through thickness.

[0073] Embodiment 11 is the sputtering target of any one of embodiments 1 -10, wherein the volume percentage of <100> texture of the target plate is from 20% to 40% through thickness.

[0074] Embodiment 12 is the sputtering target of any one of embodiments 1-11 , wherein the volume percentage of <111 > texture of the target plate is from 5% to 25% through thickness.

[0075] Embodiment 13 is the sputtering target of any one of embodiments 1 -12, wherein the sum of the volume percentage of the <110> texture and <100> texture of the target plate is from 20% to 55% through thickness.

[0076] Embodiment 14 is the sputtering target of any one of embodiments 1-13, wherein <110> texture through thickness is stable in an upper portion of the target plate.

[0077] Embodiment 15 is the sputtering target of any one of embodiments 1 -14, wherein the target plate is processed by thermomechanical processing steps.

[0078] Embodiment 16 is the sputtering target of any one of embodiments 1 -15, wherein the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 7%, optionally less than 6% or optionally less than 5%.

[0079] Embodiment 17 is a thin film formed using the sputtering target of any one of embodiments 1-16.

[0080] Embodiment 18 is a sputteringtarget comprising a target plate comprisingtantalum or tantalum alloy having a purity from 3N5 (99.95 wt%) or greater, wherein the purity is determined based on the total metals, not including any interstitial impurities, wherein the thickness is from 0.2 mm to 11 mm, and an average grain size in the range from 10 to 120 microns, wherein the sum of the volume percentage of the <100> and <110> texture is from 20% to 55% through thickness as determined by electron backscatter diffraction (EBSD); and a backing plate, wherein the volume percentage of the <100> texture in the target plate adjacent to the backing plate is greater than the volume percentage of the <110> texture adjacent to the backing plate.

[0081] Embodiment 19 is the sputtering target of embodiment 18, wherein the target plate comprises niobium, iron, cobalt, aluminum, copper, molybdenum, tungsten, titanium or alloys or mixtures thereof.

[0082] Embodiment 20 is the sputtering target of any one of embodiments 18 to 19, wherein the target plate has an interstitial content of less than 500 ppm, based on the total weight of the target plate.

[0083] Embodiment 21 is the sputtering target of any one of embodiments 18-20, wherein the tantalum or the tantalum alloy has a purity of 4N (99.99 wt%) or greater.

[0084] Embodiment 22 is the sputtering target of any one of embodiments 18-21 , wherein the tantalum or the tantalum alloy has a purity of 5N (99.999 wt%) or greater.

[0085] Embodiment 23 is the sputtering target of any one of embodiments 18-22, wherein the average grain size is in the range from 50 to 120 microns.

[0086] Embodiment 24 is the sputtering target of any one of embodiments 18-23, wherein the sum of the volume percentage of the <110> texture and <100> texture of the target plate is from 25% to 50% through thickness.

[0087] Embodiment 25 is the sputtering target of any one of embodiments 18-24, wherein the volume percentage of the <110> texture is from 2% to 20% through thickness.

[0088] Embodiment 26 is the sputtering target of any one of embodiments 18-25, wherein the volume percentage of the <110> texture is from 3% to 20% through thickness.

[0089] Embodiment 27 is the sputtering target of any one of embodiments 18-26, wherein the volume percentage of the <100> texture of the target plate is from 20% to 40% through thickness.

[0090] Embodiment 28 is the sputtering target of any one of embodiments 18-27, wherein the volume percentage of <111 > texture of the target plate is from 5% to 25% through thickness.

[0091] Embodiment 29 is the sputtering target of any one of embodiments 18-28, wherein the target plate is processed by thermomechanical processing steps.

[0092] Embodiment 30 is the sputtering target of any one of embodiments 18-29, wherein the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 7%, optionally less than 6% or optionally less than 5%.

[0093] Embodiment 31 is a thin film formed using the sputtering target of any one of embodiments 18-30.

[0094] The present disclosure is further understood by the following non-limiting examples.ExamplesExample 1

[0095] Grain maps of the full thickness tantalum sputtering target are generated. The tantalum sputtering target was a disc having a 300 mm diameter and 6.35 mm thickness. The maps are shown in FIG. 2A-2F show the grains which have particular crystallographic directions within 15° of the plate Normal Direction (“ND”; e.g., the vertical direction on the maps). Grains with a <111> orientation within 15" of ND are the darkest shaded grains (typically shown as blue for an EBSD map in accordance with the test method described herein). Grains with a <100> orientation within 15° of ND are the lightest shaded grains (typically shown as red for an EBSD map in accordance with the test method describedherein). Grains with a <110> orientation within 15° of ND are the second most dark shaded (i.e., a shade in between the lightest and darkest) grains (typically shown as yellow for an EBSD map in accordance with the test method described herein). Grains which satisfy none of the criteria are white in the figures (typically shown as gray in an EBSD map in accordance with the test method described herein). A key 200 is included with FIG. 2A to show the shading and corresponding textures, which is applicable to FIGS. 2A-2F.

[0096] FIG. 2A illustrates a map 201 of the center of a target plate and the upper portion corresponds to the sputtering portion 206 and the lower portion corresponds to the adjacent portion 208. As shown from the center map 201 in FIG. 2A, the volume percentage of the <110> texture in the sputtering portion 206 is greater than the volume percentage of the <110> texture in the adjacent portion 208. As shown in FIGS. 2A-2F, the adjacent portion 208 is 2000 microns. This pattern of the <110> texture being enriched in the sputtering portion is from the center to the edge as shown in FIGS. 2A-2F, that maps at increasing distances from the center, with FIG. 2F being the edge of the target plate.

[0097] FIG. 2A is a center map 201 of the target, FIG. 2B is a map 212 that is 76.2 mm (3.0 inches) from the center, FIG. 2C is a map 213 that is 120.1 mm (4.75 inches) from the center, FIG. 2D is a map 214 that is 152.4 mm (6.0 inches) from the center, FIG. 2E is a map 215 that is 185.4 mm (7.3 inches) from the center, and FIG. 2F is a map 216 that is 223.52 mm (8.8 inches) from the center or closest to the edge.

[0098] The volume percentage of the <110> texture adjacent to the backing plate is maintained to be low. In one embodiment, the volume percentage of the <100> texture in the target plate adjacent to the backing plate is greater than the volume percentage of the <110> texture adjacent to the backing plate.

[0099] In addition to the showing the distribution of the <110> texture in the sputtering portion 206 and the adjacent portion 208, FIGS. 2A-2F also illustrated the distribution the <110> texture from the center to the edge is also sufficient to improve sputtering rates. Accordingly, the <110> texture at the center exhibits little variation with the <110> texture at any other location away from the center.

[0100] FIG. 3 is an average texture map of the tantalum target that shows that in the adjacent portion 208 the <110> texture is less than 8%. The adjacent portion was 15-20% of the thickness of the tantalum target. The tantalum target demonstrated good uniformity when sputtering that produced films with good uniformity. The tantalum targets had low arcing, low particle generation, stable voltage and short ignition time.Example 2

[0101] Several tantalum targets where prepared and the <110> in the adjacent portion was measured as shown in Table 1 . These tantalum targets had good uniformity.Table 1Overall Texture Adjacent PortionThicknessRun ,4% <100> % <110> % <111 > % <100> % <110> % <111 >(mm)1 7.05 31.7 7.2 12.2 38.4 3.9 16.82 7.04 31.9 7.7 11.5 36.6 5.4 16.63 7.02 35.0 6.5 14.3 34.7 5.9 17.14 7 35.0 3.5 18.4 28.8 4.1 21.55 7.07 37.3 3.7 21.6 42.3 2.8 20.06 7.14 42.0 2.3 21.8 37.6 1.6 21.77 6.94 40.3 3.5 18.7 36.6 4.2 17.98 6.75 41.7 3.5 16.3 40.2 3.8 14.99 6.88 30.5 7.67 13.9 34.5 5.43 17.3710 7.08 30.7 8.55 10.4 36.9 5.91 15.7211 6.76 29.9 8.13 13.1 36.9 6.12 16.7712 6.91 31.1 5.59 15.9 27.15 4.32 22.5313 6.85 35.5 5.16 17.6 38.7 4.02 21.09

[0102] While the invention has been described in detail, modifications within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference. In addition, it should be understood that aspects of the invention and portions of various embodiments and various features recited below and / or in the appended claims may be combined or interchanged either in whole or in part. In the foregoing descriptions of the various embodiments, those embodiments which refer to another embodiment may be appropriately combined with other embodiments as will beappreciated by one of skill in the art. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and is not intended to limit.

Claims

We Claim:

1. A sputtering target comprising: a target plate comprising tantalum or tantalum alloy having a purity of 3N5 (99.95 wt%) or greater, wherein the purity is determined based on the total metals, not including any interstitial impurities, wherein the thickness is from 0.2 mm to 11 mm, and an average grain size in the range from 10 to 120 microns, wherein the volume percentage of <110> texture of the target plate is from 2% to 20% through thickness as determined by electron backscatter diffraction (EBSD); and a backing plate, wherein the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 8%.

2. The sputtering target of claim 1, wherein the tantalum alloy comprises niobium, iron, cobalt, aluminum, copper, molybdenum, tungsten, titanium or alloys or mixtures thereof.

3. The sputtering target of any one of claims 1 or 2, wherein the target plate has an interstitial content of less than or equal to 500 ppm, based on the total weight of the target plate.

4. The sputtering target of any one of claims 1 -3, wherein the target plate has an interstitial content of less than or equal to 1000 ppm, based on the total weight of the target plate.

5. The sputtering target of any one of claims 1 -4, wherein the tantalum or the tantalum alloy has a purity of 4N (99.99 wt%) or greater.

6. The sputtering target of any one of claims 1 -5, wherein the tantalum or the tantalum alloy has a purity of 5N (99.999 wt%) or greater.

7. The sputtering target of any one of claims 1 -6, wherein the average grain size is in the range from 50 to 120 microns.

8. The sputtering target of any one of claims 1 -7, wherein the volume percentage of the <110> texture is from 3% to 12% through thickness.

9. The sputtering target of any one of claims 1 -8, wherein the volume percentage of <100> texture of the target plate is from 20% to 40% through thickness.

10. The sputtering target of any one of claims 1 -9, wherein the volume percentage of <111 > texture of the target plate is from 5% to 25% through thickness.11 . The sputtering target of any one of claims 1 -10, wherein the sum of the volume percentage of the <110> texture and <100> texture of the target plate is from 20% to 55% through thickness.

12. The sputtering target of any one of claims 1-11 , wherein <110> texture through thickness is stable in an upper portion of the target plate.

13. The sputtering target of any one of claims 1 -12, wherein the target plate is processed by thermomechanical processing steps.1 . The sputtering target of any one of claims 1-13, wherein the volume percentage of the <110> texture in the target plate adjacent to the backing plate is less than 7%.

15. Athin film formed usingthe sputteringtarget of any one of claims 1-14.

Images