Tungsten-containing targets diffusion-bonded to copper alloy backing plates

Abstract

The sputtering target assembly includes a tungsten-containing sputtering target, a copper alloy backing plate attached to the tungsten-containing sputtering target, and an intermediate layer positioned between the tungsten-containing sputtering target and the copper alloy backing plate to diffusion bond them. The tungsten-containing sputtering target includes 0% to about 50% by weight of an alloying element, the remainder being tungsten. The alloying element is titanium, aluminum, or molybdenum. Methods of fabrication are also provided.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 18 / 531,641, filed December 6, 2023, and U.S. Provisional Patent Application No. 63 / 437,378, filed January 6, 2023, both of which are incorporated herein by reference in their entireties.

[0002] FIELD OF THE INVENTION The present disclosure relates to sputtering target assemblies and components for use with sputtering targets in physical vapor deposition systems. [Background technology]

[0003] Physical vapor deposition ("PVD") processes are widely used to form thin films of materials on a variety of substrates. One important area for such deposition techniques is semiconductor manufacturing. A diagram of a portion of an exemplary physical vapor deposition ("PVD") apparatus 8 is shown in FIG. 1. In one configuration, a sputtering target assembly 10 includes a backing plate 12 having a target 14 bonded thereto. A substrate 18, such as a semiconductor material wafer, is provided within the PVD apparatus 8 and spaced apart from the target 14. A surface 16 of the target 14 is the sputtering surface. As shown, the target 14 is positioned above the substrate 18 with the sputtering surface 16 facing the substrate 18. During operation, sputtered material 22 is displaced from the sputtering surface 16 of the target 14 and used to form a coating (or thin film) 20 on the substrate 18. In some embodiments, suitable substrates 18 include wafers used in semiconductor manufacturing.

[0004] In an exemplary PVD process, the target 14 is bombarded with energy until atoms from the sputtering surface 16 are ejected into the surrounding atmosphere and subsequently deposited on a substrate 18. In one exemplary use, plasma sputtering is used to deposit thin metal films onto chips or wafers for use in electronic devices.

[0005] The target 14 is formed from a metal or metal alloy that is intended to be deposited as a film on a surface thereof. During the PVD process, metal atoms are removed from the surface of the sputtering target and deposited onto a substrate 18.

[0006] The backing plate 12 may be used to support the target 14 during the PVD deposition process. The PVD deposition process may cause undesirable physical changes to the sputtering target assembly 10, which includes the target 14 and the backing plate 12. For example, the PVD deposition process may include high temperatures that distort or deform the target 14. To prevent this, the sputtering target assembly 10 and components may be designed to reduce these undesirable physical changes. For example, the backing plate 12 may be constructed to have a high heat capacity and / or thermal conductivity, which may minimize or prevent undesirable physical changes to the target 14 and the sputtering target assembly 10.

[0007] In an exemplary two-component sputtering target assembly 10 design, as illustrated in FIG. 2, the backing plate 12 is formed as a separate component from the target 14. The backing plate 12, as shown, is a single, solid plate. The target 14 is joined to the backing plate 12 by techniques such as fastening, welding, soldering, and diffusion bonding to form the sputtering target assembly 10. The backing plate 12 serves various functions, including strengthening the mechanical properties and enhancing the overall physical properties of the sputtering target assembly 10. The sputtering target assembly 10 includes the target 14 and the backing plate 12 after they are joined, as shown in FIG. 2.

[0008] One method of joining the target 14 to the backing plate 12 is by diffusion bonding the two components together. In diffusion bonded targets, bonding some target and backing plate materials is difficult due to the large difference in the coefficient of thermal expansion (CTE) between the target and backing plate materials. For example, in diffusion bonded targets, bonding some target materials, such as tungsten, to conventional backing plate materials, such as aluminum, aluminum alloy, copper, or copper alloy backing plates, is difficult due to the large difference in CTE between these materials.

[0009] When an object is made by joining two metal bodies together that have disparate CTEs, delamination or even cracking can occur when the object is heated, for example, during bonding or when used in a high-temperature environment such as PVD. As an example, when making a sputtering target assembly 10 as in Figure 2, thermal stresses can build up at interface 24 after bonding target 14 to backing plate 12 during the cooling phase when the materials are physically connected by a solid-state bond but contract at different rates.

[0010] In general, thermal stress in a system with multiple materials is proportional to the difference in CTE between the materials in the system. The relationship between thermal stress (σ) as a function of temperature change (ΔT) and the value of the difference in CTE (ΔCTE, also called CTE mismatch) can be shown using Equation 1: Equation 1: σ~ΔCTE * ΔT

[0011] What is needed is a method for bonding a tungsten-containing target to a backing plate that is an improvement over the methods previously described. Summary of the Invention

[0012] Embodiment 1 is a sputtering target assembly including a tungsten-containing sputtering target, a copper alloy backing plate attached to the tungsten-containing sputtering target, and an intermediate layer positioned between the tungsten-containing sputtering target and the copper alloy backing plate to diffusion bond them. The tungsten-containing sputtering target includes 0% to about 50% by weight of an alloying element, the remainder being tungsten. The alloying element is selected from the group consisting of titanium, aluminum, and molybdenum. The intermediate layer includes an adhesion layer directly adjacent to the tungsten-containing sputtering target, a first copper layer directly adjacent to the adhesion layer, and a second copper layer directly adjacent to the first copper layer and the copper alloy backing plate. The second copper layer has a thickness of about 0.1 inches to about 0.3 inches.

[0013] Embodiment 2 is the sputtering target assembly of embodiment 1, wherein the alloying component is titanium, and the tungsten-containing sputtering target comprises titanium in an amount between about 1% and about 30% by weight, the remainder being tungsten.

[0014] Embodiment 3 is the sputtering target assembly of embodiment 1, wherein the alloying component is titanium, and the tungsten-containing sputtering target comprises titanium in an amount between about 3% and about 15% by weight, the remainder being tungsten.

[0015] Embodiment 4 is the sputtering target assembly of embodiment 1, wherein the tungsten-containing sputtering target comprises 100 wt.% tungsten.

[0016] Embodiment 5 is the sputtering target assembly of embodiment 1, wherein the alloying component is aluminum, and the tungsten-containing sputtering target comprises aluminum in an amount between about 0.1% and about 5% by weight, the remainder being tungsten.

[0017] Embodiment 6 is the sputtering target assembly of embodiment 1, wherein the alloying component is molybdenum, and the tungsten-containing sputtering target comprises molybdenum in an amount between about 1% and about 50% by weight, the remainder being tungsten.

[0018] Embodiment 7 is the sputtering target assembly of any one of Embodiments 1-6, wherein the tungsten-containing sputtering target has a purity of at least 3N.

[0019] Embodiment 8 is the sputtering target assembly of any one of Embodiments 1 to 7, wherein the copper alloy backing plate is formed from a copper-zinc alloy, a copper-chromium alloy, or a copper-chromium-nickel-silicon alloy.

[0020] Embodiment 9 is the sputtering target assembly of any one of Embodiments 1 to 7, wherein the copper alloy backing plate is formed from C46400, C18200, or C18000.

[0021] In a tenth embodiment, the copper alloy backing plate has a thickness of about 17×10 -6 m / m℃~approx. 22×10 -6 8. The sputtering target assembly of any one of Embodiments 1 to 7, having a coefficient of thermal expansion (CTE) of m / m°C.

[0022] In an eleventh embodiment, the tungsten-containing sputtering target has a surface roughness of about 4.5×10 -6 m / m℃~approx.8×10 -6 11. The sputtering target assembly of any one of Embodiments 1 to 10, having a coefficient of thermal expansion (CTE) of m / m°C.

[0023] Embodiment 12 is the sputtering target assembly of any one of Embodiments 1-11, wherein the bond formed by the intermediate layer is at least about 98% as determined by C-scan.

[0024] Embodiment 13 is the sputtering target assembly of any one of Embodiments 1-12, wherein the average bond strength is at least about 10 ksi (68.9 MPa).

[0025] Embodiment 14 is a method for forming a sputtering target assembly, comprising: forming an adhesion layer on a back surface of a tungsten-containing target; forming and diffusion bonding a first copper layer on the adhesion layer directly adjacent to the adhesion layer; and forming and diffusion bonding a second copper layer between the first copper layer and the copper alloy backing plate, thereby diffusion bonding the tungsten-containing sputtering target to a copper alloy backing plate. The tungsten-containing target comprises 0% to about 50% by weight of an alloying element, and the remainder tungsten. The alloying element is selected from the group consisting of titanium, aluminum, and molybdenum. The second copper layer has a thickness of about 0.1 inches to about 0.3 inches.

[0026] Embodiment 15 is the method of embodiment 14, wherein the alloying component is tungsten, and the tungsten-containing sputtering target comprises titanium in an amount between about 1% and about 30% by weight, the remainder being tungsten.

[0027] Embodiment 16 is the method of embodiment 14, wherein the tungsten-containing sputtering target comprises 100 wt.% tungsten.

[0028] Embodiment 17 is the method of embodiment 14, wherein the alloying component is molybdenum, and the tungsten-containing sputtering target comprises molybdenum in an amount between about 1% and about 50% by weight, the remainder being tungsten.

[0029] Example 18 is the method of any one of Examples 14-17, wherein the copper alloy backing plate is formed from a copper-zinc alloy, a copper-chromium alloy, or a copper-chromium-nickel-silicon alloy.

[0030] Embodiment 19 is the method of any one of embodiments 14-18, wherein diffusion bonding the tungsten-containing sputtering target to the copper alloy backing plate is performed by hot isostatic pressing (HIP) at about 300°C to about 400°C and a pressure of about 15 ksi or greater.

[0031] Embodiment 20 is the method of any one of embodiments 14-19, wherein forming an adhesion layer comprises forming an adhesion layer of less than about 10 microns by electroplating.

[0032] While multiple embodiments are disclosed, still other embodiments of the present invention will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative embodiments of the invention. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not as restrictive. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 1 is a schematic diagram of a sputtering apparatus. [Figure 2] FIG. 1 is a schematic diagram of a sputtering target assembly. [Figure 3] FIG. 1 is a schematic diagram of a sputtering target assembly according to some embodiments of the present invention. [Figure 4] FIG. 1 is a process diagram of one method for making a sputtering target assembly. DETAILED DESCRIPTION OF THE INVENTION

[0034] Disclosed herein is an improved sputtering target assembly including a tungsten-containing sputtering target and a copper alloy backing plate, as well as a method for making the same. The tungsten-containing sputtering target and the copper alloy backing plate have significantly different CTEs. This difference creates large thermal stresses during cooling, such as cooling after a bonding process, which can lead to either delamination or cracking of the tungsten-containing sputtering target.

[0035] 3 is a schematic cross-sectional view of a sputtering target assembly 30 including a tungsten-containing sputtering target 32, a copper alloy backing plate 34, and an intermediate layer 36. The intermediate layer 36 is positioned between the tungsten-containing sputtering target 32 ​​and the copper alloy backing plate 34 to bond the components together.

[0036] The tungsten-containing sputtering target 32 ​​comprises tungsten as a primary component, optionally one or more alloying components selected from the group consisting of titanium, molybdenum, and aluminum, and unavoidable impurities. In some embodiments, the tungsten-containing sputtering target 32 ​​consists essentially of, or consists of, tungsten and 0% to 50% by weight of one or more alloying components. In some embodiments, the tungsten-containing sputtering target 32 ​​is formed from 100% high-purity tungsten. That is, the tungsten-containing sputtering target 32 ​​consists of tungsten with unavoidable impurities and is not a tungsten alloy. In other embodiments, the tungsten-containing sputtering target 32 ​​is formed from a tungsten alloy, such as a tungsten-titanium alloy, a tungsten-molybdenum alloy, or a tungsten-aluminum alloy. In some embodiments, the tungsten-containing sputtering target 32 ​​has a density of about 4.5×10 -6 m / m℃~approx.8×10 -6Coefficient of thermal expansion (CTE) of m / m°C, or approximately 4.5 x 10 -6 m / m℃~approx.5.5×10 -6 It has a CTE of m / m℃.

[0037] In some embodiments, the alloying element is titanium. In some embodiments, titanium is present in tungsten-containing sputtering target 32 ​​in an amount of about 1 wt % to about 30 wt %, based on the total weight of sputtering target 32. In other embodiments, titanium is present in tungsten-containing sputtering target 32 ​​in an amount of about 1 wt % to about 20 wt %, or about 3 wt % to about 15 wt %, based on the total weight of the sputtering target.

[0038] Tungsten is the major component of the tungsten-containing sputtering target 32. That is, tungsten is present in the tungsten-containing sputtering target 32 ​​in an amount greater than any other component. In some embodiments, the tungsten-containing sputtering target 32 ​​consists essentially of titanium or consists of titanium, with the remainder being tungsten. In one embodiment, the sputtering target 32 ​​contains about 10% by weight titanium, with the remainder being tungsten.

[0039] In some embodiments, tungsten is the primary component of tungsten-containing sputtering target 32, with molybdenum comprising the remainder. For example, molybdenum can be present in an amount of about 1% to about 50%, or about 20% to about 40%, or about 25% to about 35% by weight, based on the weight of the sputtering target. In some embodiments, tungsten-containing sputtering target 32 ​​consists essentially of molybdenum, or consists of molybdenum, with the remainder being tungsten.

[0040] In some embodiments, tungsten is the primary component of tungsten-containing sputtering target 32, with aluminum comprising the remainder. For example, aluminum may be present in an amount of about 0.1 wt. % to about 5 wt. % aluminum, or about 0.1 wt. % to about 1 wt. % aluminum, based on the weight of sputtering target 32.

[0041] A copper alloy backing plate 34 is connected to the tungsten-containing sputtering target 32. Copper Alloy Backing Plate 34. In some embodiments, the copper alloy backing plate 34 is formed from a copper-zinc alloy, a copper-chromium alloy, or a copper-chromium-nickel-silicon alloy. For example, the copper alloy backing plate 34 may be formed from C46400 (CuZn alloy), C18200 (Cu-1% Cr alloy), or C18000 (CuCrNiSi alloy). In some embodiments, the copper alloy backing plate 34 is a CuZn alloy. In some embodiments, the copper alloy backing plate 34 has a thickness of about 17×10 -6 m / m℃~approx. 22×10 -6 m / m°C. In comparison, tungsten has a CTE of 4.5 x 10 -6 Based on the rule of mixtures, tungsten-titanium alloys containing 1 to 30 wt.% titanium have a CTE of 4.6 to 8 × 10 -6 Tungsten aluminum alloys with a CTE of 0.1 to 5 wt.% aluminum have a CTE of 4.5 to 5.5 × 10 -6 Tungsten molybdenum having a CTE of 4.5 to 5 × 10 m / m °C and containing 1 to 50 wt % molybdenum -6 It has a CTE of m / m℃.

[0042] Those skilled in the art will recognize that tungsten-containing sputtering target 32 ​​also contains unavoidable impurities. In some embodiments, tungsten-containing sputtering target 32 ​​is a high-purity target having a purity of at least 3N (99.9%), or at least 4N (99.99%), or at least 5N (99.999%). In some embodiments, tungsten-containing sputtering target 32 ​​has a purity of 5N.

[0043] The intermediate layer 36 attaches the tungsten-containing sputtering target 32 ​​to the copper alloy backing plate 34. The intermediate layer 36 includes an adhesion layer 38, a first copper layer 40, and a second copper layer 42. The adhesion layer 38 is directly adjacent to the tungsten-containing sputtering target 32. The adhesion layer 38 is attached to the backside of the tungsten-containing sputtering target 32, opposite the sputtering surface. The adhesion layer 38 can be formed from any metal suitable for attachment to the first copper layer 40. For example, the adhesion layer 38 can be formed from nickel or titanium. In some embodiments, the adhesion layer 38 can consist of, or consist essentially of, nickel and impurities. In other embodiments, the adhesion layer 38 can consist of, or consist essentially of, titanium. The adhesion layer 38 is a thin layer. For example, the adhesion layer 38 can have a thickness of about 1 to about 10 microns. The adhesion layer 38 is an adhesion layer for the first copper layer 40.

[0044] The first copper layer 40 is directly adjacent to the adhesive layer 38. The first copper layer 40 is diffusion bonded to the adhesive layer 38. The first copper layer 40 can be formed of oxygen-free copper, such as Cu-OFE (oxygen-free electronic grade). In some embodiments, the first copper layer 40 is formed of copper that is up to 99.99% oxygen-free. The first copper layer 40 is a thin layer. For example, the first copper layer 40 can have a thickness of about 0.010 to about 0.100 inches (about 0.254 mm to about 2.54 mm).

[0045] The second copper layer 42 is directly adjacent to the copper alloy backing plate 34 and the first copper layer 40. The second copper layer 42 is diffusion bonded to the copper alloy backing plate 34 and the tungsten-containing sputtering target 32 ​​with the adhesion layer 38 and the first copper layer 40. The second copper layer 42 may be a soft metal. In some embodiments, the second copper layer 42 may be formed of oxygen-free copper, such as Cu-OFE. In some embodiments, the first copper layer 40 is formed of copper that is up to 99.99% oxygen-free. In some embodiments, the second copper layer 42 has a thickness of about 0.1 inches to about 0.3 inches (about 2.5 mm to about 7.62 mm).

[0046] 4 illustrates a method 50 for making the sputtering target assembly 30. The method 50 includes plating an adhesion layer onto a tungsten-containing sputtering target (step 52), diffusion bonding the tungsten-containing sputtering target to a first copper layer (step 54), and diffusion bonding the tungsten-containing sputtering target to a copper alloy backing plate (step 56).

[0047] In step 52, a thin layer of adhesion metal, such as nickel or titanium, is formed on the surface of the tungsten-containing sputtering target. This forms adhesion layer 38 on tungsten-containing sputtering target 32 ​​shown in FIG. 3. In some embodiments, the adhesion layer can be formed by electroplating, a PVD process, or ion plating. In some embodiments, the adhesion layer can be about 1 to about 10 microns thick.

[0048] In step 54, a tungsten-containing sputtering target with an adhesion layer is bonded to a first copper layer by diffusion bonding. This forms first copper layer 40 on adhesion layer 38 of FIG. 3. In some embodiments, the first copper layer is oxygen-free copper foil. The copper layer can be bonded to the tungsten-containing sputtering target and adhesion layer by hot pressing the components at about 700°C to about 1000°C or about 800°C to about 1000°C. The first copper layer provides a bonding surface for the second copper layer. The copper of the first copper layer and the copper of the second copper layer provide a copper-to-copper bond for the assembly.

[0049] In step 56, the tungsten-containing sputtering target having the adhesion layer and first copper layer is joined to a copper alloy backing plate by diffusion bonding. In step 56, a second copper layer is placed directly adjacent to the first copper layer on the tungsten-containing sputtering target, and a copper alloy backing plate is placed directly adjacent to the second copper layer. This assembly is bonded by hot isostatic pressing (HIP) to form the sputtering target assembly 30 of FIG. 3.

[0050] In some embodiments, the HIP process is carried out at about 300° C. to about 400° C. After the bonding process, the assembly is allowed to cool to room temperature. The low temperature of the HIP process minimizes thermal stresses between the tungsten-containing sputtering target and the copper alloy backing plate during the post-HIP cooling period.

[0051] In some embodiments, the HIP process can be carried out at a pressure of about 15 kilopounds per square inch (ksi) or greater (about 103 megapascals (MPa) or greater). For example, the HIP process can be carried out at a pressure of about 15 ksi to about 30 ksi (about 103 MPa to about 207 MPa). In some embodiments, the pressure can be about 20 ksi to about 30 ksi (about 138 MPa to about 207 MPa).

[0052] Those skilled in the art will recognize that additional steps can be performed before, after, or between the steps presented in Figure 4. For example, a tungsten-containing sputtering target can be machined after step 54 and before step 56. The sputtering target assembly can also be machined and / or cleaned after step 56.

[0053] C-scan imaging can be used to assess the bond between the tungsten-containing sputtering target 32 ​​and the copper alloy backing plate 34. In some embodiments, the bond is at least about 98%. In some embodiments, the bond is at least about 99.9%.

[0054] The bond between the tungsten-containing sputtering target 32 ​​and the copper alloy backing plate 34 is strong enough to withstand the PVD process. In some embodiments, the average bond strength is at least about 10 ksi (68.9 MPa). The average bond strength can be determined using the ram tensile test method described in Zatorski, Z. (2007) Evaluation of Steel Clad Plate Weldability Using Ram Tensile Test Method. Engineering Transactions, 55(3), 229-238.

[0055] Bonding a tungsten-containing sputtering target to a copper alloy backing plate is difficult due to the large difference in CTE. Previous methods have resulted in delamination and / or cracking of the sputtering target. Thermal stress is caused by the difference in length change (indicated by the difference in CTE) between the sputtering target and the backing plate as the materials cool after bonding. Method 50 provides a sputtering target assembly 30 in which the tungsten-containing sputtering target 32 ​​does not delaminate from the copper alloy backing plate 34. Additionally, the tungsten-containing sputtering target 32 ​​does not suffer from cracking.

[0056] In some embodiments, after a tungsten-containing sputtering target is bonded to a backing plate, for example, by HIP, the target assembly has a low crown, which is a measure of the flatness of the sputtering target. A target assembly with a low crown makes subsequent machining easier. Target assemblies with a large crown can be flattened by mechanical means in an attempt to reduce the crown. However, this can result in cracking of the sputtering target or sputtering target assembly. The low or small crown of certain sputtering assemblies after HIP (without further processing) provides an improved assembly. In some embodiments, a target assembly with a tungsten titanium sputtering target and a CuZn backing plate has a crown of less than 0.05 inches.

[0057] As used herein, the term "about" means ±10%, ±5%, or ±1%. [Example]

[0058] The following non-limiting examples illustrate various features and characteristics of the present invention, but the invention should not be construed as being limited thereto, and all percentages are by weight unless otherwise stated.

[0059] Example 1: W10Ti diffusion bonded to a CuZn backing plate A tungsten-containing sputtering target containing 10 wt. % titanium and the remainder tungsten (W10Ti) was diffusion bonded to a backing plate formed from C46400 (50 wt. % copper, 39 wt. % zinc, and 0.8 wt. % tin) (CuZn).

[0060] First, nickel was electroplated onto the backside of the W10Ti sputtering target to form an adhesion layer that was less than about 10 microns thick.

[0061] A copper layer was then formed on the adhesive layer by diffusion bonding OFE copper foil to the nickel using a hot press at about 800°C to about 1000°C.

[0062] A sputtering target assembly was fabricated by stacking a CuZn backing plate, an OFE copper layer, and a W10Ti sputtering target with nickel and copper layers. The sputtering target assembly was bonded by HIP at 300°C to about 400°C and 25.5 kilopounds per square inch (ksi) (175.8 megapascals (MPa)).

[0063] The resulting sputtering target assembly did not suffer from sputtering target delamination or cracking. The bond rate, as determined by C-scan, was 99.9%. The average bond strength was measured according to Zatorski, Z. (2007) Evaluation of Steel Clad Plate Weldability Using Ram Tensile Test Method. Engineering Transactions, 55(3), 229-238. The average bond strength (e.g., the bond between the sputtering target and the backing plate) was 13.5 ksi (93.1 MPa). The crown of the sputtering target was measured at multiple locations on the center, mid-radius, and edge of the target surface using a dial test indicator. The maximum crown was less than 0.04 inches (1.01 mm).

[0064] Example 2: W diffusion bonded to a CuZn backing plate Pure tungsten (100 wt. % tungsten with unavoidable impurities) was diffusion bonded to a backing plate formed from C46400 (50 wt. % copper, 39 wt. % zinc, and 0.8 wt. % tin) (CuZn).

[0065] First, nickel was electroplated onto the backside of the W sputtering target to form an adhesion layer that was less than about 10 microns thick.

[0066] A copper layer was then formed on the adhesive layer by diffusion bonding OFE copper foil to the nickel using a hot press at about 800°C to about 1000°C.

[0067] A sputtering target assembly was fabricated by stacking a CuZn backing plate, an OFE copper layer, and a W sputtering target with nickel and copper layers, and the sputtering target assembly was bonded by HIP at 300°C to about 400°C and 25.5 ksi (175.8 MPa).

[0068] The resulting sputtering target assembly did not suffer from sputtering target delamination or cracking. The bond rate determined by C-scan was 99.98%. The average bond strength was measured according to Zatorski, Z. (2007) Evaluation of Steel Clad Plate Weldability Using Ram Tensile Test Method. Engineering Transactions, 55(3), 229-238. The average bond strength was greater than 10 ksi (68.9 MPa).

[0069] Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the above embodiments refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the above features.

Claims

1. 1. A sputtering target assembly comprising: a tungsten-containing sputtering target comprising 0 wt. % to about 50 wt. % alloying element, the remainder being tungsten, and the alloying element being selected from the group consisting of titanium, aluminum, and molybdenum; a copper alloy backing plate attached to the tungsten-containing sputtering target; an interlayer positioned between and diffusion bonding the tungsten-containing sputtering target and the copper alloy backing plate, an adhesion layer directly adjacent the tungsten-containing sputtering target; a first copper layer directly adjacent the adhesion layer; and an intermediate layer comprising: a second copper layer directly adjacent to the first copper layer and the copper alloy backing plate, the second copper layer having a thickness of from about 0.1 inches to about 0.3 inches.

2. 10. The sputtering target assembly of claim 1, wherein the alloying component is titanium, and the tungsten-containing sputtering target comprises titanium in an amount between about 1% and about 30% by weight, with the remainder being tungsten.

3. 10. The sputtering target assembly of claim 1, wherein the alloying component is titanium and the tungsten-containing sputtering target comprises titanium in an amount of about 3% to about 15% by weight, the balance being tungsten.

4. 10. The sputtering target assembly of claim 1, wherein the tungsten-containing sputtering target comprises 100% by weight tungsten.

5. 10. The sputtering target assembly of claim 1, wherein the alloying component is aluminum and the tungsten-containing sputtering target comprises aluminum in an amount of about 0.1% to about 5% by weight, the balance being tungsten.

6. 10. The sputtering target assembly of claim 1, wherein the alloying component is molybdenum and the tungsten-containing sputtering target comprises molybdenum in an amount of about 1% to about 50% by weight, the balance being tungsten.

7. The sputtering target assembly of any one of claims 1 to 6, wherein the tungsten-containing sputtering target has a purity of at least 3N.

8. The sputtering target assembly of any one of claims 1 to 7, wherein the copper alloy backing plate is formed from a copper-zinc alloy, a copper-chromium alloy, or a copper-chromium-nickel-silicon alloy.

9. The sputtering target assembly of any one of claims 1 to 7, wherein the copper alloy backing plate is formed from C46400, C18200, or C18000.

10. The copper alloy backing plate is about 17×10 －６ m / m℃ ~ approx. 22×10 －６ The sputtering target assembly of any one of claims 1 to 7, having a coefficient of thermal expansion (CTE) of m / m°C.

11. The tungsten-containing sputtering target has a surface area of ​​about 4.5×10 －６ m / m℃ ~ approx. 8×10 －６ The sputtering target assembly of any one of claims 1 to 10, having a coefficient of thermal expansion (CTE) of m / m°C.

12. The sputtering target assembly of any one of claims 1 to 11, wherein the bond formed by the intermediate layer is at least about 98% as determined by C-scan.

13. 13. The sputtering target assembly of any one of claims 1 to 12, wherein the bond between the tungsten-containing sputtering target and the copper alloy backing plate has an average bond strength of at least about 10 ksi (68.9 MPa).

14. 1. A method for forming a sputtering target assembly, comprising: forming an adhesion layer on a backside of the tungsten-containing target, the tungsten-containing target comprising 0 wt. % to about 50 wt. % alloying element and the remainder tungsten, the alloying element being selected from the group consisting of titanium, aluminum, and molybdenum; forming a first copper layer on the adhesion layer, the first copper layer being immediately adjacent to the adhesion layer, and diffusion bonding the first copper layer; and diffusion bonding the tungsten-containing sputtering target to the copper alloy backing plate by forming and diffusion bonding a second copper layer between the first copper layer and the copper alloy backing plate, the second copper layer having a thickness of about 0.1 inches to about 0.3 inches.

15. 15. The method of claim 14, wherein forming an adhesion layer comprises forming an adhesion layer of less than about 10 microns by electroplating.

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