Sputtering target assembly, backing plate therefor and method of manufacture

Abstract

A sputter target assembly includes a target plate comprising a refractory metal or a refractory metal alloy, an adjoining backplate, and a ferritic interfacial zone. The backplate comprises 0.01-0.5 wt% iron, 34.0-40.0 wt% zinc, and 60.0-66.0 wt% copper. The ferritic interfacial zone bonds the backplate to the target plate and has a concentration of iron greater than the concentration of iron in the backplate as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS).

Description

[0001] Priority requirements

[0002] This application claims priority to U.S. Provisional Application No. 63 / 610,738, filed December 15, 2023, the entire contents and publication of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to refractory metal and refractory metal alloy target plate assemblies for use in sputtering components, including a target plate, a backing plate, and their bonding. The refractory metal and refractory metal alloy target plate is particularly bonded to the backing plate to form an iron-rich interface region. Background Technology

[0004] Sputtering is used to deposit thin films from a target onto a substrate such as a silicon wafer to fabricate any of a variety of devices. Sputtering typically involves bombarding a solid sputtering target with high-energy particles to eject atoms from the target. Several parameters affect sputtering, such as purity, interstitial content, crystal orientation, thickness uniformity, and / or grain size. By controlling the target material, sputtering deposition can be controlled to achieve fine control over thin film growth and microstructure.

[0005] Sputtering targets can be prepared by ingot metallurgy, according to which an ingot is formed (e.g., by electron beam melting of a metal) and subsequently thermomechanically processed to achieve the desired texture. Commercially available targets containing tantalum are processed from ingots obtained by melting and casting tantalum raw materials, which can include thermomechanical processes such as forging, annealing, rolling, heat treatment, and other finishing processes.

[0006] Sputtering targets can also be prepared from powdered metal raw materials, which are then properly solidified to form the resulting target. When using powdered metal as a raw material, it is generally desirable to use high-purity powders. For example, it is desirable to use powders with low levels of undesirable metal impurities and / or low oxygen content.

[0007] A backplate is attached to the target plate to support the sputtering target and its mounting in the sputtering apparatus. Importantly, the backplate also serves to provide heat dissipation during sputtering. The backplate's performance should include good electrical and thermal conductivity. The most common backplate materials include copper and stainless steel. The selected backplate should be compatible with the sputtering target material. Problems arise in components where the sputtering target delaminates or peels off from the backplate during sputtering, severely limiting component lifespan.

[0008] Using brass alloys for backplates has been considered, for example, see Japanese Patent Publication No. 1222047 A2. However, it is known that brass suffers from dezincification, which can cause the sputtering target to delaminate or peel off from the backplate.

[0009] U.S. Publication No. 2008 / 0236738 describes a method for fabricating a sputtering target assembly by using a powder layer between the target and a backing plate to assist bonding. U.S. Publication No. 2008 / 0197017 describes a sputtering target and backing plate bonded together by interlayering one or more of silver, copper, nickel, tin, titanium, and indium.

[0010] U.S. Patent No. 6,164,519 describes an explosive bonding method for a backplate to a sputtering target. Explosive bonding involves accelerating the sputtering target and / or backplate toward each other through one or more controlled detonations to form atomic bonds at the interface between the sputtering target and the backplate. This requires machining the non-bonding surfaces of the sputtering target and the backplate to obtain the final assembly dimensions.

[0011] Therefore, there is a need in the art for sputtering target assemblies that do not require additional materials, such as powder and / or interlayers, between the target and the backplate, but have improved bonding. Furthermore, there is a need for assemblies that prevent zinc stripping from the backplate. This disclosure addresses these needs. Summary of the Invention

[0012] This disclosure generally relates to a sputtering target assembly comprising a target plate bonded to a backing plate. The target plate and the backing plate are made of dissimilar materials. In one embodiment, the sputtering target assembly includes a target plate that can be diffusely bonded to the backing plate. An interface region is formed when they are bonded together. The inventors have unexpectedly discovered that the composition of the backing plate, particularly iron, influences the microstructure to form an iron-rich interface region that bonds the backing plate to the sputtering target. The iron-rich interface region limits the formation of harmful intermetallic compounds in the interface region and achieves good metallurgical bonding. In one embodiment, the backing plate may comprise an iron-containing copper-zinc alloy suitable for bonding with a target plate containing a refractory metal or refractory metal alloy, such as tantalum or a tantalum alloy of high purity. Using the sputtering target assembly can improve thin film production and extend the lifetime of the assembly during sputtering.

[0013] In one aspect, a sputtering target assembly is provided, comprising a target plate comprising a refractory metal or a refractory metal alloy; a back plate adjacent to the target plate, wherein the back plate comprises 0.01-0.5 wt% iron, 34.0-40.0 wt% zinc, and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the back plate; and an iron-rich interface region comprising the back plate to the target plate, the iron-rich interface region having a thickness, wherein the iron concentration in the iron-rich interface region, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), is greater than the iron concentration in the back plate.

[0014] The target plate of the sputtering target assembly may include a center, thickness, edge, top plane, and bottom plane, wherein the top plane is opposite to the bottom plane. The back plate of the sputtering target assembly may include a center, thickness, edge, top plane, and bottom plane, wherein the top plane is opposite to the bottom plane. An iron-rich interface region of the sputtering target assembly may be disposed between the bottom plane and the top plane of the back plate. The thickness of the interface region may be less than or equal to 10 µm, for example, less than 5 µm, less than 3 µm, or less than 1 µm. The sputtering target assembly may include the bottom plane of the target and the top plane of the back plate extending together. The bottom plane of the target may contact the top plane of the back plate. The sputtering target assembly may have a bonding strength, preferably greater than or equal to 175 MPa, preferably greater than or equal to 200 MPa, between the target plate and the back plate, such as an ultimate tensile strength.

[0015] The iron-rich interface region preferably has an enriched concentration of iron. In one embodiment, the iron concentration in the iron-rich interface region of the sputtering target assembly can be at least 3% by weight greater than the iron concentration in the backplane.

[0016] In one embodiment, the backsheet may include 0.01-0.5 wt% iron, 0.25-2.0 wt% tin, 34.0-40.0 wt% zinc, and 60.0-66.0 wt% copper, where the wt% is based on the total weight of the backsheet. Within these ranges, the backsheet may have a Zn:Fe weight ratio of 70:1 to 4000:1.

[0017] In some embodiments, the backsheet may include 0-0.1% lead by weight. Small amounts of lead may be used, and in one embodiment, the backsheet includes less than 100 ppm of lead.

[0018] The target plate of the sputtering target assembly may include refractory metals or refractory metal alloys, including tantalum, niobium, titanium, molybdenum, their alloys, or combinations thereof. Preferably, the target plate of the sputtering target assembly may include tantalum or niobium. The target plate may further include iron, cobalt, aluminum, copper, tungsten, or their alloys or mixtures. The target plate may include 0-0.1% by weight of iron or less than 100 ppm of iron.

[0019] High-purity sputtering target assemblies are preferred. In one embodiment, the target plate comprises tantalum with a total metal purity of 99.5% or greater, such as 99.95% or greater, 99.99% (4N) or greater, or more preferably 99.999% (5N) or greater. In another embodiment, the target plate comprises one of niobium, titanium, or molybdenum with a total metal purity of 99.5% or greater, such as 99.95% or greater, 99.99% (4N) or greater, or more preferably 99.999% (5N) or greater.

[0020] In one embodiment, the backplate comprises an alloy phase comprising an α-copper phase in solid solution with zinc. The backplate may include a second copper-containing phase as a β-CuZn intermetallic compound. The second copper-containing phase may be present in an amount less than 5% by volume. The backplate may include iron precipitates dispersed therein. The backplate may further comprise tin and include tin precipitates dispersed therein.

[0021] Thin films can be formed using the sputtering target assembly described herein. In one embodiment, a deposition method is used to jet atoms from the target assembly onto a substrate to form the thin film. The thin film can be homogeneous.

[0022] The sputtering target assembly disclosed in the above embodiments includes a target / backplate bond having a yield strength greater than 150 MPa, for example, greater than 155 MPa, greater than 160 MPa, greater than 165 MPa, greater than 170 MPa, or greater than 175 MPa at 0.2% offset. In one embodiment, the sputtering target assembly includes a target / backplate bond that may have an ultimate tensile strength greater than 175 MPa, for example, greater than 190 MPa, greater than 200 MPa, greater than 210 MPa, greater than 220 MPa, greater than 230 MPa, greater than 240 MPa, or greater than 245 MPa. Ultimate tensile strength is the bond strength.

[0023] In one aspect, a method for preparing a sputtering target assembly is provided, comprising providing a target plate and a backing plate comprising a refractory metal or a refractory metal alloy; and diffusion bonding a first plane of the backing plate to a second plane of the target plate in a vacuum, the second plane being adjacent to the first plane to form an iron-rich interface region to bond the backing plate to the target plate, wherein the backing plate comprises 0.01-0.5 wt% iron, 34.0-40.0 wt% zinc, and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the backing plate; and wherein the iron-rich interface region has a thickness and an iron concentration greater than the iron concentration in the backing plate, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS). The method may include wherein the diffusion bonding is performed at a temperature of 600-850°C.

[0024] In one embodiment, a sputtering target assembly includes a target plate comprising a refractory metal or a refractory metal alloy; a back plate adjacent to the target plate, wherein the back plate is composed of 0.01-0.5 wt% iron, 0.25-2.0 wt% tin, 34.0-40.0 wt% zinc, and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the back plate; and an iron-rich interface region bonding the back plate to the target plate, the iron-rich interface region having a thickness, wherein the iron concentration in the iron-rich interface region, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), is greater than the iron concentration in the back plate.

[0025] These and other non-restrictive features are described in more detail below. Attached Figure Description

[0026] The present invention is further illustrated by the following figures, wherein: Figure 1 This is a cross-sectional view illustrating the backplate of the sputtering target assembly according to the embodiment disclosed herein.

[0027] Figure 2 This document illustrates a cross-sectional view of the target plate of a sputtering target assembly according to the embodiments disclosed herein.

[0028] Figure 3 This document illustrates a cross-sectional view of the target plate / backplate pre-assembly of a sputtering target assembly according to the embodiments disclosed herein.

[0029] Figure 4 Thermomechanical processing is illustrated to form a sputtering target assembly according to the embodiments disclosed herein.

[0030] Figure 5 This document illustrates a cross-sectional view of a sputtering target assembly comprising a target plate, a back plate adjacent to the target plate, and an iron-rich interface region to which the back plate is attached, according to the embodiments disclosed herein.

[0031] Figure 6 Illustrate the binary phase diagram of Fe and Ta.

[0032] Figure 7 A micrograph of a conventional two-phase brass in which dezincification is clearly visible.

[0033] Figure 8 Explain the binary phase diagram of Cu and Zn.

[0034] Figure 9 To illustrate the target plate / backplate interface region of the sputtering target assembly according to the embodiments disclosed herein, at 75 × 75 µm 2 A graph analyzing the Fe+ signal within the area; the graph shows that the Fe content increases as a function of the diffusion binding temperature of 600-850°C.

[0035] Figure 10 A graph illustrating an overlapping line scan across the target / backplane interface of a sputtering target assembly according to the embodiments disclosed herein; the graph shows that Cu decreases with increasing Ta and Fe increases and decreases in the interface region.

[0036] Figure 11 The specification is at 75×75µm 2 ToF-SIMS analysis of the area shows the cross-section of the overlapping sputtering target assembly of Example 1C, indicating that the Fe-rich interface region is located between the copper-containing backplate and the Ta-containing target plate according to the embodiment disclosed herein.

[0037] Figure 12The ToF-SIMS analysis shows the cross-section of the overlapping sputtering target assembly of Example 1D, indicating that the iron-rich interface region Fe is located between the copper-containing backplate and the Ta-containing target plate according to the embodiments disclosed herein.

[0038] Figure 13 A graph illustrating the effect of combined temperatures of 600–850°C is shown, displaying stress-strain curves according to the embodiments disclosed herein.

[0039] Figure 14 A graph comparing the Fe+ signals between Example 1C and Example 2B.

[0040] Figure 15 The cross-section of the overlapping sputtering target assembly of Comparative Example 2B, as shown by ToF-SIMS analysis, indicates that the Fe-rich interface region is located between the copper-containing backplate and the Ta-containing target plate according to the embodiment disclosed herein.

[0041] Figure 16 This is a photomicrograph of Comparative Example 2B. Detailed Implementation

[0042] This disclosure describes sputtering target assemblies, thin films produced by such sputtering targets, and sputtering methods utilizing sputtering targets. In one embodiment, sputtering deposition can be a physical vapor deposition method for forming thin films. In forming a thin film, material from the sputtering target can be exposed to high-energy particles from plasma or gases, such as argon, krypton, xenon, neon, nitrogen, or mixtures thereof. Exposure to high-energy particles from plasma or gases causes particles from the sputtering 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 so that target material is sputtered toward the substrate.

[0043] like Figure 5 As shown, a sputtering target assembly 100 comprising a target plate 102 and a backplate 104 is disclosed. In one embodiment, the backplate 104 is bonded to the target plate 102 using solid-state bonding techniques such as diffusion bonding, brazing, fusion welding, soft soldering, mechanical fastening, epoxy bonding, friction welding, or explosive bonding. In some embodiments, the backplate 104 is bonded to the target plate 102 using diffusion bonding, as discussed in detail below. In the embodiments herein, this bonding is achieved without interlayers or similar additional materials. Therefore, there are no interlayers, intermediate materials, powders, foils, flakes, or other additives. These intermediate materials are specifically omitted for bonding the backplate 104 and the target plate 102. Such intermediate materials are unnecessary because the composition of the backplate disclosed herein strongly influences the formation of the iron-rich interface region during the diffusion bonding of the backplate to the target plate.

[0044] For example Figure 1As shown, the backing plate 104 may comprise an alloy of copper, zinc, and iron. In one embodiment, the backing plate 104 may comprise a copper-zinc alloy containing iron. Preferably, the backing plate 104 and the target plate 102 have different compositions. The backing plate is configured to fix the target plate 102 in a position suitable for sputtering deposition toward the substrate (not shown). Furthermore, the backing plate 104 may provide mechanical strength, electrical conductivity, and thermal conductivity to the sputtering target. Heat treatment can be used to provide the backing plate 104 with higher mechanical strength than the target plate 102. In some embodiments, an unbonded backing plate may also be used.

[0045] For example Figure 2 As shown, target plate 102 includes a center, a thickness (T), an edge, a top plane 112, and a bottom plane 113, wherein the top plane is opposite to the bottom plane. The bottom plane includes an adjoining portion that can be attached to a backing plate. The top plane includes a sputtered portion exposed during the sputtering process. Backing plate 104 includes a center, a thickness (B), an edge, a top plane 114, and a bottom plane 115, wherein the top plane 112 is opposite to the bottom plane 115.

[0046] like Figure 3 As shown, the target plate / backplate pre-assembly 90 is prepared by setting the top plane 114 of the backplate adjacent to and in contact with the bottom plane 113 of the target. Figure 4 Thermomechanical processing 150 applied to pre-assembled part 90 to form Figure 5 The sputtering target assembly 100. An iron-rich interface region 106 is formed between the bottom plane 113 of the target and the top plane 114 of the backing plate and has a thickness of 108. The improved bonding is due to good metallurgical bonding and the presence of an enriched concentration of iron at the iron-rich interface region 106.

[0047] The thickness of the target plate can be varied as needed depending on the application. In one embodiment, the target plate thickness can be 0.2-100 mm, for example, 0.25-100 mm, 0.3-80 mm, 0.5-75 mm, 1-60 mm, or 1-50 mm. The thickness of the backplate can also be varied as needed depending on the application. In one embodiment, the backplate thickness can be 0.2-200 mm, for example, 0.25-150 mm, 0.3-125 mm, 0.5-100 mm, 1-60 mm, or 1-60 mm. In one embodiment, the backplate is thicker than the target plate.

[0048] The iron-rich interface region has a thickness. The thickness 108 of the iron-rich interface region 106 disposed between the bottom plane of the target and the top plane of the backplate can be 1-10 µm, for example 2-8 µm or 2-5 µm. In some embodiments, the thickness of the iron-rich interface region can be less than or equal to 10 µm, for example less than 5 µm, less than 3 µm or less than 1 µm. The minimum thickness of the iron-rich interface region is sufficient to improve the bonding strength of the sputtering target assembly due to the presence of iron.

[0049] although Figure 5 A rotating configuration is shown, but sputtering target assemblies may have other configurations without departing from the embodiments described herein. In some embodiments, the sputtering target and / or backplane may have a square configuration, a rectangular configuration, a circular configuration, a tubular configuration, or a rotating configuration. The sputtering targets and / or backplanes described herein can be used for both large-scale and small-scale target assemblies. For example, the size of larger-scale target assemblies allows them to typically sputter uniformly onto wafers or other substrates with a diameter or maximum size of at least about 200 mm, at least about 300 mm, or even at least about 450 mm. Examples of such target assemblies are typically circular or rectangular plate structures with a diameter (or maximum size) exceeding about 0.2 m, about 0.3 m, or even about 0.4 m.

[0050] In one embodiment, the backplane 104 may be configured similarly to the target plate 102. It is also contemplated that the backplane 104 may have a slightly larger size than the target plate 102. Figure 5 The rotating configuration of the backplate 104 shows a radius larger than that of the target plate 102, which has a similar thickness. Other embodiments may include sputtering targets in which the backplate 104 and the target plate 102 have different thicknesses.

[0051] The sputtering target assembly described herein allows multiple target plates to be bonded to a single backing plate; that is, the target body may optionally include at least two consolidated preforms bonded together to define the resulting target plate. This allows for a greater output of target material. If a multi-block assembly is used, two or more of the resulting consolidated blocks can be bonded together to form a target body by hot isostatic pressing (e.g., simultaneously encapsulated in a suitable hot isostatic pressing vessel). These two or more blocks can be bonded together with or without any powder, foil, flakes, or other additives in the space between adjacent blocks of target material.

[0052] In the pre-assembled assembly, the backplate is adjacent to the target plate and the bottom plane of the target contacts the top plane of the backplate (e.g., Figure 3(Middle). The composition of the backplate is crucial for the formation of iron-rich interface regions during thermomechanical processing, such as diffusion bonding. The backplate comprises copper, zinc, and iron. In one embodiment, the backplate disclosed herein has a different composition than commercial brass compositions, such as C46400 (Naval Brass), C26800 (Yellow Brass), and C46200 (Japanese Navy Brass).

[0053] The inventors unexpectedly discovered that an iron concentration of 0.01–0.5 wt% in the backplate strongly influences the microstructure of the iron-rich interface region. This iron is microalloyed with copper and zinc during backplate formation. ToF-SIMS analysis of the iron in the backplate demonstrates that it migrates from the backplate to the target plate during diffusion bonding, thereby forming the interface region and providing strong bonding between the backplate and target plate. This iron enrichment can reduce the presence of brittle intermetallic phases such as the zinc-rich intermetallic β phase. In some embodiments described herein, the target plate refractory metal or refractory metal alloy is tantalum or a tantalum alloy. Figure 6 As shown, the circled portion facing 100% tantalum indicates the solubility of iron in tantalum. Unbound by theory, it is believed that the iron tends to diffuse into the tantalum to form a solid solution, which enhances bonding with the tantalum target. Therefore, at temperatures used for diffusion bonding, such as in the range of 600–850°C, the iron is attracted and migrates towards the target.

[0054] The backplate disclosed herein contains 0.01-0.5% by weight iron, 34.0-40.0% by weight zinc and 60.0-66.0% by weight copper.

[0055] In one embodiment, the backplate may contain 0.01-0.5% by weight, for example 0.01-0.4% by weight, 0.01-0.3% by weight, 0.011-0.3% by weight, 0.012-0.3% by weight, 0.015-0.3% by weight, 0.02-0.2% by weight, or 0.025-0.1% by weight of iron. At the upper limit, the backplate may contain less than or equal to 0.5% by weight, for example less than 0.4% by weight, less than 0.3% by weight, less than 0.2% by weight, less than 0.1% by weight, less than 0.05% by weight, less than 0.02% by weight, less than 0.015% by weight, or less than 0.013% by weight of iron. Regarding the lower limit, the backsheet may contain greater than or equal to 0.01 wt% iron, for example, greater than 0.011 wt%, greater than 0.012 wt%, greater than 0.013 wt%, greater than 0.014 wt%, greater than 0.015 wt%, greater than 0.02 wt%, or greater than 0.025 wt% iron. When the amount of iron in the backsheet is less than 0.01 wt%, the peeling rate increases, which leads to poor performance of the sputtering assembly. In one embodiment, the backsheet may preferably contain about 0.011-0.013 wt% iron based on the total weight of the backsheet.

[0056] The sputtering target assembly described herein may have a higher iron concentration in the iron-rich interface region than in the backing plate. In one embodiment, the iron concentration in the iron-rich interface region may be at least 2% by weight greater than the iron concentration in the backing plate, for example, at least 3% by weight, at least 4% by weight, at least 5% by weight, at least 6% by weight, at least 7% by weight, at least 8% by weight, at least 9% by weight, at least 10% by weight, or more.

[0057] The backplate composition disclosed herein also includes zinc. For example, in addition to the microalloyed iron content in the backplate as disclosed above, the backplate composition includes a lower zinc concentration and a higher copper concentration compared to typical brass.

[0058] Brass containing less than 15% by weight of zinc is generally resistant to dezincification, while brass containing more than 15% by weight of zinc is prone to dezincification. As is known, biphasic (two-phase) brass (α+β) is more prone to dezincification than α brass. In biphasic brass, the β phase is preferentially attacked, leaving discrete pieces of dealloyed metal. Brass with a conventional two-phase structure is shown in... Figure 7 middle.

[0059] This is important because the backplate composition disclosed herein prevents dezincification of the backplate even at higher zinc contents, such as 34.0–40 wt% zinc. The zinc content in this paper affects the formation of a single copper-containing α-copper phase as a solid solution with zinc in the backplate. This zinc content avoids the formation of a second β-copper-containing phase as a β-CuZn intermetallic compound, such as… Figure 8 The binary phase diagram of Cu-Zn is shown. Importantly, the β-CuZn intermetallic phase is largely prevented, which can be detrimental and lead to dezincification. Dezincification can cause backplate failure due to cracking or delamination within the backplate and / or delamination from the attached target plate. By synergistically combining zinc content that prevents dezincification in the backplate with microalloyed iron that promotes bonding between the backplate and the target plate, the resulting sputtering target assembly exhibits excellent bonding and long lifespan.

[0060] In one embodiment, the backsheet may contain 34.0-40.0% by weight, for example 34.0-39.0% by weight, 35.0-38.0% by weight, 35.0-37.0% by weight, or 35.5-36.5% by weight of zinc. At the lower limit, the backsheet may contain greater than or equal to 34.0% by weight of zinc, for example greater than 35.0% by weight or greater than 35.5% by weight of zinc. At the upper limit, the backsheet may contain less than or equal to 40.0% by weight, for example less than 39.0% by weight, less than 38.0% by weight, less than 37.0% by weight, or less than 36.5% by weight of zinc. Preferably, the backsheet contains approximately 36.0% by weight of zinc based on its total weight.

[0061] In one embodiment, the backplane may contain 60.0-66.0% by weight, for example 61.0-66.0% by weight, 62.0-66.0% by weight, 63.0-66.0% by weight, or 63.5-66.0% by weight of copper. At the lower limit, the backplane may contain greater than or equal to 60.0% by weight, for example greater than 61.0% by weight, greater than 62.0% by weight, greater than 63.0% by weight, or greater than 63.5% by weight of copper. At the upper limit, the backplane may contain less than or equal to 66.0% by weight, for example less than 65.0% by weight of copper. Preferably, the backplane contains approximately 63.5-66.0% by weight of copper based on its total weight.

[0062] In some embodiments, the backplate may further comprise additional metals. These additional metals do not affect the migration of iron to the interface region. In one embodiment, the backplate may comprise 0.25-2.0 wt%, for example 0.45-1.0 wt%, 0.65-0.85 wt%, or 0.70-0.80 wt% tin. At the lower limit, the backplate may comprise greater than or equal to 0.25 wt%, for example greater than 0.45 wt%, greater than 0.65 wt%, or greater than 0.70 wt% tin. At the upper limit, the backplate may comprise less than or equal to 2.0 wt%, for example less than 1.0 wt%, less than 0.85 wt%, or less than 0.80 wt% tin. The backplate may preferably comprise about 0.75 wt% tin based on the total weight of the backplate. This tin forms a deposit that improves the mechanical properties of the backplate.

[0063] The backsheet according to the embodiments described herein does not contain lead, which is harmful to the environment. The backsheet may contain 0-1000 ppm lead, 0-500 ppm lead, 0-200 ppm lead, or 0-100 ppm lead. The backsheet used for sputtering target assemblies herein is preferably lead-free, for example, less than 500 ppm, less than 200 ppm, or less than 100 ppm lead.

[0064] In this document, the synergistic combination of zinc and iron in a copper-zinc-iron alloy in the backplate used for sputtering target assemblies can be characterized by a Zn:Fe weight ratio of 70:1 to 4000:1 in the backplate. In one embodiment, the backplate may include a Zn:Fe ratio of 70:1 to 4000:1, for example, 100:1 to 3500:1 or 1500:1 to 2500:1. In some embodiments, the backplate includes a Zn:Fe ratio of 1440:1.

[0065] In a particular embodiment, the sputtering target assembly includes a target plate comprising a refractory metal or a refractory metal alloy; a back plate adjacent to the target plate, wherein the back plate is composed of 0.01-0.5 wt% iron, 0.25-2.0 wt% tin, 34.0-40.0 wt% zinc and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the back plate; and an iron-rich interface region connecting the back plate to the target plate, the iron-rich interface region having a thickness, wherein the iron concentration of the iron-rich interface region, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), is greater than the iron concentration in the back plate.

[0066] As disclosed above, the backplate and target plate are co-paired, with iron preferentially migrating from the backplate to the target plate to bond the backplate to the target plate. Figure 6 As shown and discussed above, tantalum and / or tantalum alloys are suitable as target plates for sputtering target assemblies as described herein because iron is attracted and / or migrates from the backplane to the target plate to form an iron-rich interface region. Target plates suitable for the assemblies described herein may comprise tantalum, niobium, titanium, molybdenum, alloys thereof, or combinations thereof.

[0067] The sputtering target assembly described herein includes a target plate comprising a refractory metal, particularly tantalum or a tantalum alloy. In one embodiment, the purity of the tantalum or tantalum alloy is based on the total metal content of the target plate being 99.5% or greater, for example 99.95% or greater, 99.99% (4N) or greater, or more preferably 99.999% (5N) or greater. In some embodiments, the tantalum alloy may comprise niobium, iron, cobalt, aluminum, copper, molybdenum, tungsten, titanium, or alloys or mixtures thereof. For the purposes of this invention, the purity of the tantalum or tantalum alloy is determined based on the total metal content, excluding any interstitial impurities (C, O, N, H). In some embodiments, the target plate comprises tantalum with a purity of 99.99% (4N) or 99.999% (5N) or greater.

[0068] In one embodiment, the target plate contains high-purity tantalum to allow the target plate to have a purity of 15.4-16.7 g / cm³. 3 For example, 15.9-16.7 g / cm³ 3 Or 16.4-16.7 g / cm³ 3 Density within the range. While the backplate can provide structural integrity, the target plate can also be strong enough to withstand the normal stresses encountered during subsequent assembly operations (such as three-point straightening assembly, creep straightening, or some other operations that subject the target to stress during these operations) without breaking.

[0069] The target plate may contain one of the following metals with a purity of 99.5% or greater, such as 99.95% or greater, 99.99% (4N) or greater, or more preferably 99.999% (5N) or greater. In some embodiments, the target plate contains one of the following metals with a purity of 99.99% (4N) or greater, or 99.999% (5N) or greater.

[0070] In one embodiment, the target plate, based on its total weight, may have an interstitial content of less than or equal to 500 ppm. 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 a range, the interstitial content may be greater than 0 to 500 ppm, for example, 10-500 ppm or 100-400 ppm. For embodiments where the target plate is prepared by a powder process, the target plate, based on its total weight, may have an interstitial content of less than or equal to 1000 ppm, for example, less than 950 ppm, less than 750 ppm, less than 700 ppm, less than 500 ppm, less than 400 ppm, or less than 350 ppm. In a range, the interstitial content of a target plate prepared by a powder process may be greater than 0 to 1000 ppm, for example, 10-1000 ppm, 50-950 ppm, or 100-600 ppm or 100-500 ppm. When processing powder, a scavenging metal such as magnesium may be used to reduce oxygen.

[0071] The target plate may further contain iron, cobalt, aluminum, copper, tungsten, or alloys or mixtures thereof. These are considered minor alloying components and / or unavoidable impurities, for example, present in amounts less than 0.1% by weight.

[0072] The target plate according to the embodiments described herein is free of iron. The target plate described herein may contain 0-1000 ppm of iron, for example 0-500 ppm, 0-200 ppm, or 0-100 ppm of iron. The target plate used in the sputtering target assembly described herein is preferably iron-free, for example, less than 500 ppm, less than 200 ppm, less than 100 ppm, or less than 1 ppm of iron.

[0073] As with the backplane, the target plate according to the embodiments herein is lead-free. The target plate herein may contain 0-1000 ppm lead, for example 0-500 ppm lead, 0-200 ppm lead, or 0-100 ppm lead. The target plate used in sputtering target assemblies herein may preferably be lead-free, for example, less than 500 ppm, less than 200 ppm, less than 100 ppm lead, or less than 1 ppm lead.

[0074] As discussed above, the backplate composition disclosed herein promotes strong bonding with the target plate to form a sputtering target assembly while preventing zinc dezincification within the backplate. This is achieved by controlling the iron and zinc contents separately. Ideally, the backplate microstructure should comprise a (single) copper-containing phase of α-copper in solid solution with zinc. Ideally, no second copper-containing phase of β-CuZn intermetallic phase is present. In one embodiment, the backplate comprises an alloy phase comprising a solid solution of zinc and α-copper phases. The backplate may include a second alloy phase comprising a solid solution of zinc and β-copper phases; however, this second alloy phase comprising a solid solution of zinc and β-copper phases is present in an amount less than or equal to 10% by volume, for example, less than 5% by volume, less than 2% by volume, or less than 1% by volume, as measured using image analysis with ImageJ software or other known image analysis techniques.

[0075] The microstructure of the backsheet may further include precipitates dispersed therein. Precipitates in the backsheet (formed by minor components) may include iron precipitates. Additionally or alternatively, a backsheet further comprising tin may include tin precipitates dispersed therein.

[0076] The sputtering target assembly includes a backplate with reduced grain size. The microstructure of the backplate includes an average grain size in the range of 10-120 μm. In one embodiment, the backplate may have an average grain size in the range of 10-120 μm, for example, 15-120 μm, 20-120 μm, 30-120 μm, 40-120 μm, or 50-120 μm. Grain size measurements are performed according to ASTM E112-12.

[0077] The sputtering target assembly includes a target plate with reduced grain size. The microstructure of the target plate includes an average grain size in the range of 10-120 μm. In one embodiment, the target plate may have an average grain size in the range of 10-120 μm, for example, 15-120 μm, 20-120 μm, 30-120 μm, 40-120 μm, or 50-120 μm.

[0078] The sputtering target assembly includes an iron-rich interface region with a fine grain size. The microstructure of this iron-rich interface region includes an average grain size in the range of 0.1–10 μm. In one embodiment, the iron-rich interface region may have an average grain size in the range of 0.1–10 μm, for example, 0.1–7 μm, or 0.1–5 μm, 0.1–4 μm, 0.1–3 μm, 0.1–2 μm, or 0.1–1 μm. Grain size measurements are performed according to ASTM E112-12.

[0079] The sputtering target assembly disclosed in the above embodiments is used to sputter thin films according to the embodiments herein. Uniformity of the film thickness is crucial. In integrated circuits (where hundreds are simultaneously produced on a silicon wafer), poor deposition, such as on a sputtering target, leads to detrimental properties such as insufficient diffusion barriers or restricted vias or trenches. Non-uniformity of the deposited film can render the device unusable and result in a loss of total manufacturing cost up to the test point, as repair or rework is typically not possible.

[0080] Thin films for semiconductor applications are produced using a method according to the preceding embodiments, wherein the variation in film thickness uniformity (percentage of non-uniformity) is 3% or less, and the variation in thin film resistance within and between wafers is 3% or less.

[0081] Particle generation and / or other adverse conditions that may prematurely shorten the lifespan of sputtering targets can also be avoided by using the sputtering target components described herein.

[0082] The sputtering target assembly disclosed in the above embodiments exhibits a bonding strength, i.e., an ultimate tensile strength, greater than or equal to 175 MPa, between the target plate and the backing plate. Bond strength measurements are collected for samples undergoing diffusion bonding at varying temperatures, such as 600-850°C. In one embodiment, the sputtering target assembly may have a bonding strength greater than or equal to 175 MPa, for example, greater than or equal to 180 MPa, greater than or equal to 185 MPa, greater than or equal to 190 MPa, greater than or equal to 200 MPa, greater than or equal to 210 MPa, greater than or equal to 220 MPa, greater than or equal to 240 MPa, greater than or equal to 260 MPa, or greater than or equal to 280 MPa. Furthermore, the sputtering target assembly disclosed in the above embodiments includes a backing plate having an ultimate tensile strength of 175-1300 MPa, such as 175-1200 MPa, 180-1100 MPa, 180-400 MPa, 180-300 MPa, 185-275 MPa, or more preferably 190-250 MPa. The strength measurements were performed according to the Arcan tensile test.

[0083] In addition to bond strength, the sputtering target assembly disclosed in the above embodiments includes a target / backplate bond that can have a yield strength greater than or equal to 150 MPa, for example greater than or equal to 155 MPa, greater than or equal to 160 MPa, greater than or equal to 165 MPa, greater than or equal to 170 MPa, or greater than or equal to 175 MPa at 0.2% offset. Yield strength measurements at 0.2% offset are performed according to Arcan tensile testing.

[0084] In one embodiment, a method for preparing a sputtering target assembly as described in the above embodiment includes providing a target plate and a backing plate, followed by a bonding process, such as a diffusion bonding process. The target plate comprises a refractory metal or a refractory metal alloy. The backing plate comprises 0.01-0.5 wt% iron, 34.0-40.0 wt% zinc, and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the backing plate. The target plate and the backing plate are arranged adjacent to each other. The method includes diffusion bonding a first plane of the backing plate to a second plane of the target plate in a vacuum, the second plane being adjacent to the first plane. The diffusion bonding can be performed at a temperature in the range of 600-850°C, forming an iron-rich interface region to bond the backing plate to the target plate. This iron-rich interface region has a thickness and an iron concentration greater than the iron concentration in the backing plate, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS).

[0085] The provided target plate comprises target material that can be produced using powder or rod stock via thermomechanical processing steps. In one embodiment, tantalum (or other refractory metal) powder rod stock can be cold isostatically pressed, then hot isostatically pressed, and subsequently thermomechanically processed (i.e., a series of cross rollers). One or more machining and / or surface finishing steps of the target plate may occur after the hot isostatic pressing step. For example, surface material can be removed by grinding and / or polishing. One or more structural features (e.g., one or more features for fixing, receiving O-rings in a backplate for high vacuum applications, or other features) may also be machined. To produce the sputtering target assembly described above, the teachings herein also include attaching a backplate to the target plate.

[0086] Tantalum powder (and / or other refractory metal powders, including niobium, titanium, molybdenum, or combinations thereof) can also be used as target materials. Sputtering targets according to this teaching can be prepared by consolidating the powders of this teaching. Consolidation can be sintering, hot isostatic pressing, hot extrusion, or one or any combination thereof. A density in the range of about 82-88% of the theoretical density can be achieved by cold isostatic pressing the powder pellet under suitable pressure (e.g., to an initial state at about 220 MPa). The cold isostatically pressed powder, still in the container, can be hot isostatically pressed for a suitable time under suitable temperature and pressure conditions (e.g., a period of about 6 hours at a temperature of about 1250°C and a pressure of about 207 MPa) to achieve a density close to the theoretical density (e.g., at least 98% of the theoretical density). The resulting hot isostatically pressed body can be removed from the container and can be processed (e.g., by cutting and / or machining to the final dimensions).

[0087] In one embodiment, the method of preparing the target plate includes providing a powder of tantalum or other refractory metal having a purity of at least 99.95% by weight, for example, at least 99.99% by weight, or more preferably at least 99.995% by weight, and having an oxygen content of less than 75 ppm, for example, less than 60 ppm or less than 50 ppm, and / or a maximum magnesium content of less than 10 ppm (or even 5 ppm). The powder may have a particle size of less than 1000 μm, for example, less than 850 μm, less than 650 μm, less than 500 μm, less than 350 μm, or even less than 250 μm. For example, about 95% by weight, about 85% by weight, and about 75% by weight of all particles may have a particle size of at least 10 μm, for example, at least 40 μm, at least 65 μm, or at least 90 μm. Approximately 95% of all particles may have a particle size of less than 1000 μm, for example, less than 850 μm, less than 650 μm, less than 500 μm, less than 350 μm, or less than 250 μm. In one embodiment, no particles in the powder exceed 1000 μm.

[0088] In one embodiment, 25-65% by weight, for example 29-56% by weight or even 35-47% by weight, of the powder may have a particle size greater than 65 μm, for example greater than 150 μm, greater than 250 μm, greater than 500 μm, greater than 650 μm, or greater than 850 μm, but less than about 1000 μm. Therefore, the embodiments described herein may use powder containing 25-65% by weight, for example 29-56% by weight or even 35-47% by weight, of particles having a particle size less than 1000 μm, for example less than 850 μm, less than 650 μm, less than 500 μm, less than 350 μm, or less than 250 μm, but greater than about 10 μm. For effective consolidation of the target plate, the method may use powder containing at least 10% by weight of particles having a particle size greater than 150 μm, which yields effectively consolidated agglomerates (e.g., due to thermal isostatic pressing). Preferably, the method can use powder containing at least 20% by weight, for example at least 30% by weight, at least 40% by weight, or at least 50% by weight of particles having a particle size greater than 150 μm.

[0089] Unless otherwise stated, powder particle size is determined by sieve analysis in accordance with ASTM B214-07 (2011). Furthermore, unless otherwise stated, particle size refers to the size before consolidation.

[0090] The powder can be isostatically pressed at temperatures up to 1400°C, such as up to 1325°C, up to 1250°C, up to 1100°C, up to 1080°C, or up to 1000°C, to define a target. The pressing pressure can be in the range of 100-300 MPa, such as about 170-250 MPa.

[0091] For example, without limitation, the material can be pressed into a disc-shaped body that is bombarded during the sputtering process.

[0092] In one embodiment, the rolling method can facilitate planar orientation of the target material. The amount and distribution of strain introduced by this rolling method can be controlled by several factors, including asymmetric rolling, the diameter of the rolling rolls, the rolling speed, and the reduction rate. In one embodiment, it is not necessary to limit the method, provided that the desired planar orientation can be achieved.

[0093] Sputtering targets containing tantalum or tantalum alloys are particularly suitable for forming thin films for optical fibers, semiconductor wafers, and integrated circuits. It is also contemplated to produce thin films for any of many electronic components or devices (e.g., as layers, such as barrier layers, electrode layers, as part of a semiconductor, as part of an integrated circuit, or others), such as televisions, video displays, smartphones, tablets, personal digital assistants, navigation devices, sensors, portable entertainment devices (e.g., video players, music players, etc.), or even photovoltaic devices. Alternatively, or in addition to tantalum as the target material in the methods described above, the following can be used: niobium, titanium, molybdenum, their alloys, or combinations thereof. The target plate may further contain iron, cobalt, aluminum, copper, tungsten, or their alloys or mixtures.

[0094] Importantly, as discussed above, the backplate contains copper, zinc, tin, and iron in specific controlled amounts to form an iron-rich interface region via diffusion bonding with the aforementioned target plate.

[0095] This disclosure will be more readily understood by referring to the following detailed description of the desired implementation and the embodiments included therein. In the following specification and subsequent claims, numerous terms will be referred to that should be defined as having the following meanings.

[0096] 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 definition herein shall prevail. Preferred methods and materials are described below, but similar or equivalent methods and materials may be used in the implementation or testing of this 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 are not intended to be limiting.

[0097] The singular forms “a,” “a,” and “the” include plural references unless the context clearly indicates otherwise.

[0098] The term “comprising” as used in the specification and claims may include embodiments “consisting of” and “substantially composed of”. The terms “comprising,” “including,” “having,” “may,” “contains,” and variations thereof as used herein are intended as open-ended transitional phrases requiring the presence of a specified ingredient / step while allowing for the presence of other ingredients / steps. However, such descriptions should be interpreted as also describing the composition or method as “consisting of the listed ingredients / steps” and “substantially composed of the listed ingredients / steps,” which allows for the presence of only the specified ingredient / step and any impurities that may result from it, while excluding other ingredients / steps.

[0099] When the numerical values ​​in this application specification and claims relate to sputtering target components or component composition compositions, such as backplate compositions, target plate compositions, etc., they reflect the average value of the composition. The numerical values ​​disclosed herein should be understood to include the same numerical values ​​when reduced to the same number of significant figures and numerical values ​​that differ from the stated values ​​by less than the experimental error of conventional measurement techniques of the type described in this application used to determine the values.

[0100] All ranges disclosed herein include the stated endpoints and may be combined independently (e.g., a range of "1-40 μm" includes endpoints 1 μm and 40 μm, as well as all intermediate values). The endpoints and any values ​​of the ranges disclosed herein are not limited to exact ranges or values; they are sufficiently imprecise to include values ​​close to these ranges and / or values.

[0101] The approximate language used herein can be used to modify any quantitative expression that can be altered without changing the fundamental function it involves. Therefore, in some cases, a value modified by one or more terms such as “about” and “substantially” may not be limited to the specified exact value. The modifier “about” should also be considered as disclosing a range defined by the absolute values ​​of these two endpoints. For example, the expression “about 2–10” also discloses the range “2–10”. The term “about” can refer to ±10% of the indicated number. For example, “about 10%” can refer to a range of 9–11%, and “about 1” can refer to 0.9–1.1.

[0102] For the numerical ranges listed in this article, intermediate numbers with the same precision are explicitly considered. For example, for the range of 6-9, the numbers 7 and 8 are considered in addition to 6 and 9, and for the range of 6.0-7.0, the numbers 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 considered.

[0103] The terms “greater than” and “less than” as used herein may also include numbers associated with them. In other words, “greater than” and “less than” can be interpreted as “greater than or equal to” and “less than or equal to”, respectively. Consider that this expression could subsequently be modified in the claims to include “or equal to”. For example, “greater than 4.0” could be interpreted, and subsequently modified in the claims, as “greater than or equal to 4.0”.

[0104] Some of the components and steps disclosed herein may be considered optional. In some cases, the disclosed compositions, methods, etc., may explicitly exclude one or more of the aforementioned components or steps, for example, through the wording of the claims. This is considered by the inventors herein. For example, the wording of the claims may be modified to state that the disclosed compositions, methods, streams, etc., do not utilize or include one or more of the aforementioned components or steps, such as tin (or any other of the aforementioned additives). Such negative limitations are taken into consideration, and this text is intended to support negative limitations on the components, steps, and / or features.

[0105] Example

[0106] Examples 1A-1D. Sputtering target assemblies were prepared and the bonding strength was tested.

[0107] Example 1 Backplate composition: 38.66% by weight zinc, 0.4% tin, 0.012% by weight iron, 0.13% by weight lead and balance copper. The balance of 0.3% by weight or less is interstitial matter and / or unavoidable impurities.

[0108] The backplate and target plate are brought into contact along their prepared common extension adjoining surfaces to form a pre-assembled component. The surfaces are prepared and cleaned, and then the pre-assembled component is diffuse-bonded in a hot press at various temperatures in an argon atmosphere.

[0109] Examples 1A, 1B, 1C and 1D were prepared and diffused together at temperatures of 600°C, 700°C, 800°C and 850°C, respectively.

[0110] The mechanical and electrical properties of Examples 1A, 1B, 1C, and 1D were then tested.

[0111] Figure 9-12 The results confirmed the existence of an iron-rich interface region. Figure 9 This indicates that the Fe content in the interface region increases as a function of diffusion binding temperature, with the Fe intensity increasing from 600°C to 850°C. The Fe content in the target / backplane interface region is 75 × 75 µm. 2 Fe+ signals were collected within the analysis area.

[0112] Figure 10The thickness of the iron-rich interface region is shown by an overlay line scan illustrating the target / backplane interface of the sputtering target assembly according to Example 1D, which is diffusely bonded at a temperature of 850°C. The figure shows a decrease in Cu, an increase and decrease in Fe, and an increase in Ta measured across the interface from the backplane to the target. This data indicates that the thickness of the iron-rich interface region is approximately 1.4 µm.

[0113] The iron-rich interface region of Example 1C, which is diffused and bonded at a temperature of 800°C, is further as follows: Figure 11 The cross-section of the sputtering target assembly analyzed using ToF-SIMS is shown. The overlay of the main images (three insets labeled Fe, Ta, and Cu) shows the iron-rich interface region, where, for Example 1C, Fe is disposed between the copper-containing backplate and the Ta-containing target plate.

[0114] The iron-rich interface region of Example 1D, which is diffused and bonded at a temperature of 850°C, is further as follows: Figure 12 A cross-section of the sputtering target assembly analyzed using ToF-SIMS is shown. The overlay of the main images (three insets labeled Fe, Ta, and Cu) shows the iron-rich interface region, where, for Example 1D, Fe is disposed between the copper-containing backplate and the Ta-containing target plate.

[0115] No evidence of zinc depletion at the interface was found in the analyzed examples. Narrow regions of zinc enrichment were observed at the interface, which increased with increasing binding temperature.

[0116] The stress-strain curves for Examples 1A, 1B, 1C, and 1D are shown in... Figure 13 The effect of bonding temperature on the values ​​of 0.2% offset yield strength and ultimate tensile strength (UTS) is shown in Table 1 below. UTS represents the bond strength. The 0.2% offset yield strength and UTS were obtained using the Arcan tensile method. A bowtie sample was obtained from a sputtering target assembly and placed on a 10kN Arcan fixture designed by Grip Engineering. The fixture was then placed in an Instron tensile testing machine. This test fixture allows the sample to be run under pure tension or shear.

[0117]

[0118] As shown in Table 1, Example 1B, bonded at 700°C, has the highest yield strength of 182.7 MPa at 0.2% offset, while Example 1D, bonded at 850°C, has the highest ultimate tensile strength of 248.2 MPa.

[0119] Examples 2A-2B: Comparative Examples

[0120] The comparative example used the same conditions as Example 1, diffusion bonding at 800°C, to produce a composition of 36.8 wt% zinc, 0.74 wt% tin, 0.009 wt% lead, 0.008 wt% and balance copper. The specified elements comprise 99.8 wt%. The balance 0.2 wt% or less is interstitial matter and / or unavoidable impurities.

[0121] Figure 14 To compare the Fe content in the interface region at a diffusion bonding temperature of 800°C between Example 1C and Example 2B, the Fe content in the target / backplate interface region was measured at 100 × 100 µm. 2 Fe+ signals were collected from Comparative Example 2B within the analysis area.

[0122] The iron-rich interface region of Comparative Example 2B, which diffuses and binds at a temperature of 800°C, is further as follows: Figure 15 The cross-section of the sputtering target assembly analyzed using ToF-SIMS is shown. The overlay of the main images (three insets labeled Fe, Ta, and Cu) shows the iron-rich interface region, where, for Example 2B, Fe is disposed between the copper-containing backplate and the Ta-containing target plate.

[0123] The 0.2% offset yield strength and ultimate tensile strength were obtained using the Arcan tensile method and are listed in Table 2 below.

[0124]

[0125] As shown in Table 2, the sputtering target assemblies prepared with the same composition under the same conditions exhibited significant variability between Comparative Examples 2A and 2B. Therefore, this variability degrades the performance of the sputtering target assemblies and is expected to lead to target-backplate delamination. Furthermore, the ultimate tensile strength reported for the comparative examples was lower than the values ​​in Table 1.

[0126] Figure 16 This is a photomicrograph of Comparative Example 2B. (Compared to...) Figure 7 Compared to conventional sputtering components, Figure 16 The micrographs show less of the β phase at the interface.

[0127] Implementation Plan

[0128] The following implementation plan is hereby disclosed.

[0129] Implementation Scheme 1. A sputtering target assembly comprising a target plate comprising a refractory metal or a refractory metal alloy; a back plate adjacent to the target plate, wherein the back plate comprises 0.01-0.5 wt% iron, 34.0-40.0 wt% zinc and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the back plate; and an iron-rich interface region bonding the back plate to the target plate, the iron-rich interface region having a thickness, wherein the iron concentration in the iron-rich interface region, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), is greater than the iron concentration in the back plate.

[0130] Implementation Scheme 2. The sputtering target assembly of Implementation Scheme 1, wherein the target plate includes a center, a thickness, an edge, a top plane and a bottom plane, wherein the top plane is opposite to the bottom plane.

[0131] Implementation Scheme 3. The sputtering target assembly of Implementation Scheme 2, wherein the backplate includes a center, a thickness, an edge, a top plane of the backplate and a bottom plane of the backplate, wherein the top plane of the backplate is opposite to the bottom plane of the backplate.

[0132] Implementation Scheme 4. A sputtering target assembly of any one of Implementation Schemes 1-3, wherein the iron-rich interface region is disposed between the bottom plane of the target and the top plane of the backplate.

[0133] Implementation Scheme 5. A sputtering target assembly of any one of Implementation Schemes 1-4, wherein the thickness of the interface region is less than 10µm, or less than 5µm, or less than 3µm or less than 1µm.

[0134] Implementation Scheme 6. A sputtering target assembly of any one of Implementation Schemes 1-5, wherein the bottom plane of the target and the top plane of the backplate extend together.

[0135] Implementation Scheme 7. A sputtering target assembly of any one of Implementation Schemes 1-6, wherein the bottom plane of the target contacts the top plane of the backplate.

[0136] Implementation Scheme 8. The sputtering target assembly of any one of Implementation Schemes 1-7 has a bonding strength between the target plate and the back plate greater than or equal to 175 MPa, preferably greater than or equal to 200 MPa.

[0137] Implementation Scheme 9. A sputtering target assembly of any one of Implementation Schemes 1-8, wherein the iron concentration in the iron-rich interface region is at least 3% greater by weight than the iron concentration in the backplate.

[0138] Implementation Scheme 10. A sputtering target assembly of any one of Implementation Schemes 1-9, wherein the backplate further comprises 0.25-2.0% by weight tin.

[0139] Implementation Scheme 11. A sputtering target assembly of any one of Implementation Schemes 1-10, wherein the backplate contains 0-0.1% by weight (1000 ppm) of lead.

[0140] Implementation Scheme 12. A sputtering target assembly of any one of Implementation Schemes 1-11, wherein the backplate contains less than 100 ppm of lead.

[0141] Implementation Scheme 13. A sputtering target assembly of any one of Implementation Schemes 1-12, wherein the backplate has a Zn:Fe weight ratio of 70:1 to 4000:1.

[0142] Implementation Scheme 14. A sputtering target assembly of any one of Implementation Schemes 1-13, wherein the refractory metal or refractory metal alloy of the target plate comprises tantalum, niobium, titanium, molybdenum, alloys thereof, or combinations thereof.

[0143] Implementation Scheme 15. A sputtering target assembly of any one of Implementation Schemes 1-14, wherein the target plate further comprises iron, cobalt, aluminum, copper, tungsten, or alloys or mixtures thereof.

[0144] Implementation Scheme 16. A sputtering target assembly of any one of Implementation Schemes 1-15, wherein the target plate contains 0-0.1% by weight (1000 ppm) of iron.

[0145] Implementation Scheme 17. A sputtering target assembly of any one of Implementation Schemes 1-16, wherein the target plate contains less than 100 ppm of iron.

[0146] Implementation Scheme 18. A sputtering target assembly of any one of Implementation Schemes 1-17, wherein the target plate contains tantalum with a purity of 99.99% (4N) or greater.

[0147] Implementation Scheme 19. A sputtering target assembly of any one of Implementation Schemes 1-18, wherein the tantalum has a purity of 99.999% (5N) or greater.

[0148] Implementation Scheme 20. A sputtering target assembly of any one of Implementation Schemes 1-19, wherein the target plate contains one of niobium, titanium or molybdenum with a purity of 99.99% (4N) or greater.

[0149] Implementation Scheme 21. A sputtering target assembly of any one of Implementation Schemes 1-20, wherein one of niobium, titanium or molybdenum has a purity of 99.999% (5N) or greater.

[0150] Implementation Scheme 22. A sputtering target assembly of any one of Implementation Schemes 1-21, wherein the backplate comprises an alloy phase containing a copper-containing phase as a solid solution of zinc.

[0151] Implementation Scheme 23. A sputtering target assembly of any one of Implementation Schemes 1-22, wherein the backplate comprises a second copper-containing phase as a β-CuZn intermetallic compound, the second copper-containing phase being present in an amount of less than 5% by volume.

[0152] Implementation Scheme 24. A sputtering target assembly of any one of Implementation Schemes 1-23, wherein the backplate further includes an iron precipitate dispersed therein.

[0153] Implementation Scheme 25. A sputtering target assembly of any one of Implementation Schemes 1-24, wherein the backplate further comprises tin and includes tin deposits dispersed therein.

[0154] Implementation Scheme 26. A thin film formed using a sputtering target assembly of any one of Implementation Schemes 1-25.

[0155] Implementation Scheme 27. A sputtering target assembly of any one of Implementation Schemes 1-26, wherein the backplate has an ultimate tensile strength of 175-1300 MPa.

[0156] Implementation Scheme 28. A method for preparing a sputtering target assembly, comprising providing a target plate and a back plate comprising a refractory metal or a refractory metal alloy; and diffusion bonding a first plane of the back plate to a second plane of the target plate in a vacuum, the second plane being adjacent to the first plane to form an iron-rich interface region to bond the back plate to the target plate, wherein the back plate comprises 0.01-0.5 wt% iron, 34.0-40.0 wt% zinc and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the back plate; and wherein the iron-rich interface region has a thickness and an iron concentration greater than the iron concentration in the back plate, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS).

[0157] Implementation Scheme 29. The method of Implementation Scheme 28, wherein diffusion bonding is carried out at a temperature of 600-850°C.

[0158] Implementation Scheme 30. A sputtering target assembly comprising a target plate containing a refractory metal or a refractory metal alloy; a back plate adjacent to the target plate, wherein the back plate is composed of 0.01-0.5 wt% iron, 0.25-2.0 wt% tin, 34.0-40.0 wt% zinc and 60.0-66.0 wt% copper, wherein the wt% is based on the total weight of the back plate; and an iron-rich interface region bonding the back plate to the target plate, the iron-rich interface region having a thickness, wherein the iron concentration of the iron-rich interface region, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), is greater than the iron concentration in the back plate.

[0159] Although the invention has been described in detail, modifications within its spirit and scope will readily be apparent to those skilled in the art. In view of the foregoing discussion, relevant knowledge in the art, and the references discussed above for background and detailed description, all of which are incorporated herein by reference. Furthermore, it should be understood that aspects and portions of the various embodiments of the invention, as well as the various features listed below and / or in the appended claims, can be combined or interchanged, in whole or in part. In the foregoing description of the various embodiments, those embodiments relating to another embodiment can be suitably combined with other embodiments, as will be understood by those skilled in the art. Moreover, those skilled in the art will understand that the foregoing description is merely illustrative and not intended to be limiting.

Claims

1. A sputtering target assembly, comprising: Target plate containing refractory metal or refractory metal alloy; A backplate adjacent to the target plate, wherein the backplate comprises: 0.01-0.5% by weight of iron 34.0-40.0% zinc by weight, and 60.0-66.0% copper by weight The weight percentage mentioned therein is based on the total weight of the backplate; and The backplate is bonded to the iron-rich interface region of the target plate, the iron-rich interface region having a thickness. The iron concentration in the iron-rich interface region, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), is greater than the iron concentration in the backplate.

2. The sputtering target assembly of claim 1, wherein the target plate includes a center, a thickness, an edge, a target top plane, and a target bottom plane, wherein the top plane is opposite to the bottom plane, and wherein the back plate includes a center, a thickness, an edge, a back plate top plane, and a back plate bottom plane, wherein the back plate top plane is opposite to the back plate bottom plane.

3. The sputtering target assembly of claim 1 or 2, wherein the iron-rich interface region is disposed between the bottom plane of the target and the top plane of the back plate, wherein the thickness of the interface region is less than 10µm, preferably less than 5µm, more preferably less than 3µm or more preferably less than 1µm.

4. The sputtering target assembly of claim 3, wherein the bottom plane of the target extends together with the top plane of the back plate.

5. The sputtering target assembly of claim 3 or 4, wherein the bottom plane of the target contacts the top plane of the backplate.

6. The sputtering target assembly of any one of claims 1-5, having a bonding strength of greater than or equal to 175 MPa, preferably greater than or equal to 200 MPa, between the target plate and the back plate.

7. The sputtering target assembly of any one of claims 1-6, wherein the iron concentration in the iron-rich interface region is at least 3% greater by weight than the iron concentration in the backing plate.

8. The sputtering target assembly of any one of claims 1-7, wherein the backplate further comprises 0.25-2.0% by weight tin.

9. The sputtering target assembly of any one of claims 1-8, wherein the backplate contains 0-0.1% by weight (1000 ppm) of lead, preferably the backplate contains less than 100 ppm of lead.

10. The sputtering target assembly of any one of claims 1-9, wherein the refractory metal or refractory metal alloy of the target plate comprises tantalum, niobium, titanium, molybdenum, alloys thereof, or combinations thereof.

11. The sputtering target assembly of any one of claims 1-10, wherein the target plate comprises iron, cobalt, aluminum, copper, tungsten or alloys or mixtures thereof, provided that the target plate contains 0-0.1% by weight (1000 ppm) of iron.

12. The sputtering target assembly of any one of claims 1-11, wherein the target plate contains tantalum with a purity of 99.99% (4N) or greater, preferably with a purity of 99.999% (5N) or greater.

13. The sputtering target assembly of any one of claims 1-12, wherein the backplate comprises an alloy phase containing a copper-containing phase as a solid solution of zinc.

14. The sputtering target assembly of any one of claims 1-13, wherein the backplate comprises a second copper-containing phase as a β-CuZn intermetallic compound, the second copper-containing phase being present in an amount of less than 5% by volume.

15. The sputtering target assembly of any one of claims 1-14, wherein the backplate further comprises an iron precipitate dispersed therein.

16. A thin film formed using a sputtering target assembly according to any one of claims 1-15.

17. A method for manufacturing a sputtering target assembly, comprising: Provide target plates and back plates containing refractory metals or refractory metal alloys; as well as In a vacuum, the first plane of the backplate is diffused and bonded to the second plane of the target plate, the second plane being adjacent to the first plane, thereby forming an iron-rich interface region to bond the backplate to the target plate. The backplate comprises: 0.01-0.5% by weight of iron 34.0-40.0% zinc by weight, and 60.0-66.0% copper by weight; The weight percentage is based on the total weight of the backplate; and The iron-rich interface region has a thickness and an iron concentration greater than the iron concentration in the backplate, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS).

18. The method of claim 17, wherein diffusion bonding is carried out at a temperature of 600-850°C.

19. A sputtering target assembly, comprising: Target plate containing refractory metal or refractory metal alloy; A backplate adjacent to the target plate, wherein the backplate is composed of the following: 0.01-0.5% by weight of iron 0.25-2.0% tin by weight 34.0-40.0% zinc by weight, and 60.0-66.0% copper by weight The weight percentage mentioned above is based on the total weight of the backplate; and the iron-rich interface region of the backplate being bonded to the target plate, the iron-rich interface region having a thickness, The iron concentration in the iron-rich interface region, as determined by time-of-flight secondary ion mass spectrometry (ToF-SIMS), is greater than the iron concentration in the backplate.

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