WO2004076706A2

WO2004076706A2 - A method of forming sputtering target assembly and assemblies made therefrom

Info

Publication number: WO2004076706A2
Application number: PCT/US2004/005538
Authority: WO
Inventors: Robert B. Ford; Christopher A. Michaluk; Charles E. Wickersham, Jr.
Original assignee: Cabot Corporation
Priority date: 2003-02-25
Filing date: 2004-02-24
Publication date: 2004-09-10
Also published as: TW200506080A; WO2004076706A3; US20040262157A1

Abstract

A method of forming a sputtering target assembly is described that involves explosively bonding a target grade plate and a backing plate member to form a bonded preform having dimensions such that a large target or several target assemblies can be obtained. The method includes partitioning the bonded preform into a plurality of sputtering target assemblies. An interlayer can optionally be disposed between the target grade plate and the backing plate member before bonding. A bond quality test sample can be produced by the method. The sputtering target assemblies, the bonded preform, and the bond quality test sample are further described.

Description

METHOD OF FORMING SPUTTERING TARGET ASSEMBLY

AND ASSEMBLIES MADE THEREFROM

This application claims the benefit under 35 U.S.C. §119(e) of prior U.S. Provisional Patent Application No. 60/450,196 filed February 25, 2003, which is incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a method of forming a sputtering target assembly. More specifically, the method includes the preferred use of explosion bonding to form a sputtering target assembly.

[0002] Numerous bonding techniques are used to bond sputtering target assembly components (e.g., a sputter target or target blank and a backing plate) together, such as soldering, brazing, diffusion bonding, mechanical fastening, epoxy bonding, friction welding, explosion bonding, etc. Each of the bonding techniques has its own advantages and disadvantages. A common disadvantage of conventional bonding techniques is the individual bonding of a target and a backing plate, i.e., sputtering target assemblies are formed one at a time. Singularly forming sputtering target assemblies has several drawbacks. First, it can be quite time-consuming and resource intensive, owing to the batch nature of production and inherent costs of the bonding process. Another drawback concerns quality control. Currently, a representative sample of sputtering target assemblies is typically dedicated for purposes of evaluating bond quality or bond integrity. However, variables in the bonding process affecting bond integrity can lead to uncertainty as to the relatedness of the bond quality of one sputtering target assembly to that of another. Moreover, sacrificing a certain percentage of otherwise usable sputtering target assemblies for quality control purposes adds to the overall cost of sputtering target assembly production.

[0003] Another disadvantage of conventional bonding techniques is that they are feasible only for a sputtering target of limited size. That is due, in part, to the fact that shear failure of conventional bonds increases with increasing temperatures reached during use (i.e., in the sputtering process). The debonding risk is even more possible as the size of the target increases. Accordingly, thin films deposited on large area substrates, e.g., glass panels used for fabricating flat panel displays, are typically foπned by sputtering a sputtering target assembly comprised of a mosaic of several conventional-sized targets. The sputtering behavior of the edges of the individual target "tiles" may differ from that of the bulk of the target array, resulting in a deposited film having diminished thickness uniformity. The ability to produce a single sputtering target having a large area and a high strength, high integrity bond to a backing plate represents an improvement to the current sputtering target fabrication technology.

[0004] The present invention shows that explosion bonding or explosive bonding produces a bond of superior strength and is accomplished without subjecting the bonding materials to elevated temperatures. Accordingly, explosive bonding produces a durable bond while avoiding many of the undesirable effects of heating the sputtering target assembly components during bonding such as mechanical stress, grain growth, and in the case of components having dissimilar coefficients of thermal expansion, warping. However, in the past, several technical and manufacturing related issues had prevented explosive bonding from being used for the fabrication of sputtering targets. First, the properties of the sputtering target can be altered after being subjected to an explosive shock wave. Specifically, in the case of tantalum, it is known that explosive shocking of the material generates "deformation twins^'" throughout the microstructure. In addition, explosive bonding has been deemed a relatively costly bonding technique compared to conventional bonding processes. At least some of the additional cost of explosion bonding is attributed to added material costs associated with what is commonly referred to as the "edge effect." Explosive bonding can require that the starting target materials be oversized to compensate for predictable damage at the periphery of the sputtering target assembly, i.e., the edge effect. An alternative solution is to incorporate a " "momentum trap" along the edge of the explosive bonded workpiece. The momentum trap is comprised of a metal having a similar density and impedance to that of the target material, and acts to absorb the trailing compressive shock wave with minimal reflection of a tensile wave. [0005] Accordingly, a need exists for a method to improve upon the bonding process to reduce the cost of and improve the quality control process in forming bonded sputtering target assemblies, generally, as well as to minimize the effective unusable area of an explosively bonded sputtering target assembly.

SUMMARY OF THE PRESENT INVENTION [0006] It is therefore a feature of the present invention to provide an improved method of bonding a target and a backing plate to form a sputtering target assembly. [0007] Another feature of the present invention is to provide a method for forming multiple sputtering target assemblies simultaneously.

[0008] A further feature of the present invention is to provide a method of bonding a target and a backing plate in which a bond quality test sample is formed in the process. [0009] Another further feature of the present invention is to provide a method of manufacturing a sputtering target and backing plate assembly having a large sputtering surface area. [0010] An additional feature of the present invention is to provide a method to explosively bond a target grade plate and backing plate whereby the metallurgical properties of the target plate are not significantly altered by the bonding process.

[0011] Yet another feature of the present invention is to provide a method to explosively bond a target plate and a backing plate so as to minimize the defectively bonded area resulting from the explosive bonding process.

[0012] Additional features and advantages of the present invention will be set forth in part in the description that follows, and in part will be apparent from the description, or may be learned by practice of the present invention. The objectives and other advantages of the present invention will be realized and attained by means of the elements and combinations particularly pointed out in the description and appended claims.

[0013] To achieve these and other advantages, and in accordance with the purposes of the present invention, as embodied and broadly described herein, the present invention relates to a method of forming a sputtering target assembly comprising explosively bonding a target grade plate and a backing plate member to form a bonded preform having dimensions sufficient to be divided into two or more targets. The method then involves partitioning the bonded preform to form a plurality of sputtering target assemblies. The method optionally includes disposing an interlayer between the target grade plate and the backing plate member before bonding.

[0014] The present invention further relates to a bonded preform having dimensions such that it can be partitioned to form a plurality of sputtering target assemblies. [0015] The present invention also relates to a sputtering target assembly including a target, a backing member, and an interlayer disposed therebetween, wherein the sputtering target assembly is preferably formed by partitioning a bonded preform.

[0016] Also, the present invention relates to a bond quality test sample that is produced as a byproduct of an explosive bonding method of forming a sputtering target assembly. [0017] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide a further explanation of the present invention, as claimed.

[0018] The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate various aspects of the present invention and, together with the description, serve to explain the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS [0019] Fig. 1 is a perspective view of a target grade plate in the shape of a rectangle before bonding.

[0020] Fig. 2 is a perspective view of a backing plate member in the shape of a rectangle before bonding.

[0021] Fig. 3 is a perspective view of an optional interlayer in the shape of a rectangle before bonding.

[0022] Fig. 4 is a perspective view of a bonded preform having a bonded target grade plate and a bonded backing plate member of similar shape and dimensions.

[0023] Fig. 5 is a perspective view of a bonded preform having a bonded target grade plate, a bonded backing plate member, and a bonded interlayer.

[0024] Fig. 6 is a perspective view of a sputtering target assembly having a flange comprising a portion of the backing plate. [0025] Fig. 7 is a perspective view of a sputtering target assembly having an optional interlayer and with a flange comprising a portion of the backing plate.

[0026] Fig. 8 is a perspective view of a sputtering target assembly having an optional interlayer and with a flange comprising a portion of the backing plate and a portion of the interlayer.

DETAILED DESCRIPTION OF THE PRESENT INVENTION [0027] A method according to the present invention for forming a sputtering target assembly involves explosively bonding a target grade plate and a backing plate member to form a bonded preform, and optionally partitioning the bonded preform to form a plurality of sputtering target assemblies. An interlayer can optionally be disposed between the target grade plate and the backing plate member before bonding. The present invention further relates to forming a large target which is bonded onto a backing plate. This bonded target is larger than conventional target sizes and can be useful in applications where a series or mosaic of targets are needed to form a large sputter surface area.

[0028] In more detail, the preform that is optionally divided into multiple target assemblies preferably includes two components, namely, a backing plate member having a bonding surface and a sputter target grade plate or target grade plate having a bonding surface and having a sputter surface. The backing plate member can be any suitable metal material usable as a backing plate in sputtering applications. The target or target materials can be any material capable of being sputtered. Examples of the backing plate member material include, but are not limited to, copper, or a copper alloy, tantalum, niobium, titanium, aluminum, and alloys thereof, such as TaW, NbW, TaZr, NbZr, TaNb, NbTa, TaTi, NbTi, TaMo, NbMo, and the like. Examples of target grade plate materials that can be bonded by the method of the present invention, include, but are not limited to, tantalum, niobium, cobalt, titanium, copper, aluminum, and alloys thereof.

[0029] No limitation exists as to the type of materials used in the target grade plate and the backing plate member. The thicknesses of the backing plate and the target grade plate can be any suitable thickness used for forming sputtering target assemblies. For purposes of the present invention, the target grade plate or sputter target grade plate can include a plate having dimensions larger than the dimensions for a finished sputter target. In more detail, the target grade plate refers to the starting material which has dimensions totaling the combined dimensions of two or more conventional finished targets and preferably three or more or four or more conventional targets. In other words, the dimensions of the target grade plate are such that multiple finished targets can optionally be cut from the target grade plate after bonding onto the backing plate member. As can be understood from the description of the invention, the target grade plate is a large plate. Similarly, the backing plate member for purposes of the present invention has similar dimensions to the target grade plate. Examples of suitable thicknesses of the backing plate member and of the target grade plate include, but are not limited to, a backing plate with a thickness of from about 0.25 or less to about 2 inches or more, and a target grade plate with a thickness ranging from about 0.06 inches to about 1 inch or more. In the present invention, the target grade plate materials to be bonded with the backing plate member can be target grade material, for instance, as described in U.S. Patent No. 6,348,113 (Michaluk et al.), incorporated in its entirety by reference herein. This patent shows examples of plate that can be prepared from starting ingots, plates or billets. The purity, texture, and/or grain size and other properties, including size and the like are not critical to the present invention. The powder used to make the target grade plate as well as the target itself can have any purity with respect to the metal. For instance, the purity can be 99% or greater such as from about 99.5% or greater and more preferably 99.95% or greater and even more preferably 99.99% or greater, or 99.995% or greater or 99.999% or greater. The target grade plate can have any suitable grain size (e.g., average grain sizes of less than 300 microns, less than 100 microns, less than 50 microns, less than 20 microns) and/or texture. For instance, the texture can be random, a primary (111) texture, or a primary (100) texture that can be on the surface or throughout the entire thickness of the target. Preferably, the texture is uniform. Also, the target can have a mixed (111):(1 10) texture throughout the surface or throughout the entire thickness of the target. In addition, the target can be substantially void of textural banding, such as substantially void of (100) textural banding.

[0030] The target grade plate and the backing plate member can have any shape and/or dimensions. Preferably, the target grade plate and the backing plate member are substantially of the same shape and the same dimensions. Optionally, the backing plate member can have dimensions in excess of the dimensions of the target, or, alternatively the target grade plate can have dimensions in excess of the dimensions of the backing plate member. In a preferred embodiment, both the target grade plate and the backing plate member are substantially rectangular or circular in shape, having a length of from about 1 ft or less to about 5 ft or more, and a width of from about 1 ft or less to about 5 ft or more, or diameters of from 6 inches or less to 5 feet or more. Any dimensions or ranges therein can be used. Other shapes of the target grade plate and the backing plate member can have similar surface areas. Other dimensions for the bonded preform or bonded target/backing plate includes sputter surface areas of about 1.5 m² or greater. Preferred sputter surface areas are from about 1.5 m² to about 10 m² and more preferably from about 2 m² to about 6 m². Another way to describe one aspect of the invention is a bonded target/backing plate wherein the bonded target/backing plate has a rectangular dimension of 1.5 m or greater for the length and 1.5 m or greater for the width or if the bonded target/backing plate is circular, a circular diameter of at least 1.5 m. Preferred dimensions are 1.5 m to about 3 m in length and from about 1.5 m to about 3 m in width. Similarly, the circular diameter can be from about 1.5 m to about 3 m or more. Preferably, the bonded target is a molecular bond, and more preferably is explosion bonded. When explosion bonded targets are formed, the bonded target/backing plate can have a surface area of 400 cm or higher, such as from about 500 cm² to about 1.5 m². With respect to diameters, with explosion bonded target/backing plates of the present invention, the dimensions can be a length of from greater than 20 cm, and more preferably greater than 25 cm in length to about 3 m in length with the width being greater than 20 cm, and preferably greater than 25 cm to about 3 m. As indicated above, with such large sputter surface areas, the need for mosaic sputter targets or a series of sputter targets placed next to each other can be avoided or minimized. By using a single target or less targets to formed the mosaic, a more uniform sputtered thin film can be achieved for a variety of uses including the capacitor area, plasma screen area, and the like. The explosion bonding of the present invention makes the preparation of large targets especially useful since a uniform bond exists throughout the bonded surfaces of the target and backing plate and explosion bonding permits the formation of a large bonded target where other bonding techniques would have great difficulty in forming a bonded target having such a continuous sputter surface area.

[0031] As to explosively bonding, the target grade plate and the backing plate member are arranged so that the bonding surfaces of each are facing each other. Preferably, the periphery of the target grade plate corresponds to the periphery of the backing plate member. The target grade plate and the backing plate member can be fixed in place using any conventional technology, such as clamps, bands of metal strips, vices, and other locking devices. The target grade plate and the backing plate member can be fixed in place such that a gap is created and maintained between them before bonding. Optionally, the target grade plate and the backing plate member can be placed one atop the other, preferably with a standoff device disposed therebetween, for example, as described in U.S. Patent No. 6,164,519 (Gilman et al), which is incorporated in its entirety by reference herein. An explosive charge can be located behind the target grade plate, the backing plate member, or both to achieve explosion bonding. Preferably, an explosive charge is located behind the backing plate member while the target grade plate remains stationary, for example, against a steel anvil, so that the backing plate is accelerated or exploded into the target grade plate. [0032] Generally, the amount of explosive charge is a charge sufficient to provide a bond between the target grade plate and the backing plate member. Generally, the amount of explosive charge for a 1 inch thick backing member with a gap of about 0.25 inch ranges from about 0.018 pounds/in.² for CIO 100 copper backing plate to about 0.024 pounds/in.² for C 18200 copper alloy backing plate using dynamite packed to a density of 1 g/cc. Other explosives such as Pentolite, TNT, Trimonite No. 1, C4 or other suitable explosives may be used, and the explosive charge is preferably adjusted for the explosive energy. For additional information on the calculation of the explosive charge see the article by R. J. Carlson, V. D. Linse and R. H. Wittman, Materials Engineering 68, 70 (1968), incorporated in its entirety by reference herein.

[0033] In explosion bonding, it is preferred to maintain a gap between the bonding members, i.e., the exploded members, or the exploded member and the stationary member, before detonating the explosive. In the absence of such a gap, the bond may not adequately form, or, may not form at all. Furthermore, surface impurities that are removed from the bonding surfaces by the jetting that occurs during bonding can escape via the gap and thus are not trapped between the bonded members. Accordingly, in one embodiment of the present invention, a gap can exist between the backing plate member and the target grade plate. Any manner in which to create a gap between the backing plate member and target grade plate can be used.

[0034] Having a gap permits either the target grade plate or the backing plate member upon explosion to reach its optimal velocity before impact with the stationary member. On the other hand, placing the bonding members at a less than optimal distance from each other achieves a less than optimal bonding velocity, and thus a superior bond is not achieved. Alternatively, if the distance between the bonding members is too great, then the accelerated or exploded member is at less than maximum velocity when it impacts the stationary member, and thus a superior bond is not achieved.

[0035] According to one embodiment, explosively bonding the target grade plate and the backing member forms a bonded preform. Figure 4 is an example of a bonded preform. The bonded preform can have any shape and/or dimensions depending upon the shapes and dimensions of the target grade plate and the backing plate member, the orientation of the bonding members before the explosion, and any deformation of the periphery after the explosion. Preferably, the bonded preform is of sufficient dimensions to be divided or partitioned to form a plurality of sputtering target assemblies. Preferably, the periphery of the bonded preform is substantially defined by both the target grade plate and the backing plate member. Optionally, the periphery of the bonded preform can be substantially defined by the periphery of the backing plate member or the target grade plate. The bonded preform can be in any form, such as, a plate, a sheet, a slab, or the like. In a preferred embodiment, the surface area of the bonded preform is substantially rectangular or circular in shape, having a length of from about 1 ft or less to about 5 ft or more, and a width of from about 1 ft or less to about 5 ft or more, or similar circular diameters. Other shapes of the bonded preform can have similar surface areas.

[0036] Preferably, the bonded preform has a sputter target having metallurgical properties that are similar to the target grade plate. For example, explosively bonding a target grade plate having an average grain size of less than about 100 microns and a texture substantially void of (100) textural bands according to the present invention preferably forms a bonded preform having a sputter target having an average grain size of less than about 100 microns and a texture substantially void of (100) textural bands. In addition, as a result of the explosive bonding, the bonded preform preferably has a backing plate that is harder than the backing plate member prior to being bonded, as measured quantitatively, for example, in Rockwell B scale. For instance, the hardness is increased by 5% or more, such as 10% or more, and 30%-60% or more, hi one specific example, a backing plate, like C46400 went from a Rockwell B scale hardness of 63 before explosion bonding to a bulk hardness of 85 and an interface hardness of 100 after bonding.

[0037] The bond preform preferably has a bond interface between the target grade plate and the backing plate member, the bond interface having superior strength. For example, the bond strength can be from 10,000 p.s.i. to about 75,000 p.s.i. or higher, which is approximately twice the typical bond strength achieved by, for example, diffusion bonding. Other ranges include from about 25,000 p.s.i. to about 55,000 p.s.i., and from about 40,000 p.s.i. to about 56,000 p.s.i., and the like. This bond strength is preferably uniform through the bonded surface. As stated above, increased bond strength is particularly important as the diameter of the sputter target increases. The bond interface formed by the present invention can include or not include interdifflision of the target grade plate and the backing plate member. With less interdifflision, the sputter target and the backing plate member can be more easily separated for recycling after use, for example, by reducing the amount of the reclaimed metal of either being contaminated with the other.

[0038] As to partitioning (which is completely optional), partitioning involves dividing or sectioning the bonded preform to form a plurality of sputtering target assemblies. The formed sputtering target assemblies can have any shape, and the shapes may vary from one sputtering target assembly to another. Sectioning the bonded preform can be accomplished by any conventional cutting and machining technique. Examples of such cutting techniques can include, but are not limited to, boring, milling, grinding, electrode discharge machining, waterjet abrasive cutting, laser cutting, plasma cutting, flame-cutting, sawing, use of a punch press, or other suitable method. The cutting pattern or cutting design for the bonded preform can be predetermined. A surface of the bonded preform can be marked or scribed with the predetermined cutting pattern. Preferably, the cutting pattern maximizes the usable or viable area of the bonded preform. In other words, the unused area of the bonded preform is minimized. A suitable computer program can be used to generate the cutting pattern. The cutting pattern may be programmed into a cutting device adapted to automatically control the cutting process. For example, an abrasive waterjet device can be programmed to cut the bonded preform.

[0039] Areas of the bonded preform that are too small or otherwise unsuitable for producing a sputtering target assembly can be cut into bond quality test samples. Preferably, the test samples are taken from areas adjacent to the bonded sputtering target assemblies formed. Cutting the bonded preform to form the test samples can be accomplished by any conventional cutting and machining technique previously discussed. A test sample can be identified such that its location relative to a formed sputtering target assembly can be recorded. Such test samples can then be used for purposes of bond evaluation and quality control analyses and the like. The test sample can serve as a historical record for bond integrity of one or more sputtering target assemblies that are cut from an area of the bonded preform approximate the test sample. The test sample can have any size and/or dimensions (e.g. 1 inch or less to 5 inches or more in diameter).

[0040] After the individual sputtering target assemblies are optionally cut from the bonded preform, the desired shape and dimensions of the finished sputtering target assembly can be formed using the cutting and machining techniques previously described. The finished sputtering target assembly can be of any shape and/or dimensions, such as a disc, and preferably conforming to original equipment manufacturer specifications. Optionally, at least a portion of the periphery of the bonded target, the bonded backing member, or a combination thereof, can be removed to form a flange on the sputtering target assembly. A portion of the periphery of the bonded target can be removed such that the flange comprises both the target and the backing member. Leaving a portion of the target in the flange area has the effect of providing a protective sputtering layer over the flange which reduces the unintended or incidental sputtering of the backing plate material. A portion of the periphery of the bonded target can be removed down to the bond such that the flange comprises the backing member, as shown, for example, in Fig. 6. A portion of the periphery of the bonded target can be removed down to the bond and a portion of the periphery of the backing member can be removed such that the flange comprises the backing member. At this point, any conventional processing and finishing of the sputtering target assembly can be done, such as polishing and the like. These same or some of these steps can be used even if the large bonded target is not cut. [0041] As an option, at least one interlayer can be disposed between the target grade plate and the backing plate member before bonding. The interlayer layer can be bonded between the target grade plate and backing plate member by explosive bonding, thereby forming a bonded preform having a bonded interlayer, as shown, for example, in Fig. 5. The interlayer can be any conventional interlayer material, such as, but not limited to, in the case of tantalum bonding to copper alloy backing plates, niobium, zirconium, titanium, or vanadium or other materials that can enhance the bond quality. The technical paper by Oberg et ah, Metallurgical Transactions A, 16, 841 (1985), incorporated in its entirety by reference herein, provides a description of the thermodynamic principles for choosing a suitable bonding interlayer. The interlayer can have any shape, regular or irregular, and/or dimensions. A periphery of the interlayer can be less than or greater than the periphery of either the target grade plate or the backing plate member. The interlayer can cover from about 10 to about 100% of the bonding surface of the target grade plate. The interlayer can cover from about 10 to about 100% of the bonding surface of the backing plate member. The interlayer can have a thickness of from about 0.01 to about 0.09 inches, and preferably has a thickness of from about 0.02 to about 0.06 inches. More than one interlayer can be used.

[0042] An interlayer can also be created by having a plasma jet created during the explosive bonding so as to transport materials from the anvil into the bond interface area. This plasma jet is created from the explosion and the movement of air in between the plate and backing plate. The plasma jet is capable of removing material from the anvil surface and then getting trapped in between the plate and backing plate. In one example, a steel anvil was used with a tantalum target and C 18200 backing plate. Iron from the anvil was detected in the tantalu -C 18200 bond interface. For instance, the interlayer is formed by striping material from an anvil and depositing the material at the bond interface using the explosion bonding plasma jet. If the anvil material does not provide improved interlayer bonding, then a coating (or multi-coatings) on the anvil can be used to enhance bonding. For example, any material that is capable of enhancing the bond strength between the target and backing plate can be used to enhance bonding. Specific examples include titanium, nickel, and other metals or any alloys thereof that are conventionally used as interlayers and other examples are the materials previously mentioned herein. The coating can be any thickness. [0043] The interlayer can be fixed in place before bonding of the target grade plate and the backing plate member using any suitable method, including attaching the interlayer to either the target grade plate or the backing plate member. For example, the interlayer can be friction welded, spot welded, stir welded, explosively bonded, or diffusion bonded to either of the bonding members. Alternatively, the interlayer can be located atop the bonding surface of one of the bonding members without attaching the interlayer to either bonding member. Alternatively, the interlayer can be maintained in a position between the bonding members such that a gap is created between the interlayer and both bonding surfaces. After bonding, as described above, a portion of the periphery of the interlayer can be machined and cut away in the flange areas of the sputtering target assembly, or, alternatively, can remain intact on the flange areas of the target material. Figure 7 is an example of a sputtering target assembly formed according to the method of the present invention wherein a portion of the periphery of the target and a portion of the periphery of the interlayer have been completely removed such that the flange comprises a portion of the backing plate. Figure 8 is an example of a sputtering target assembly formed according to the method of the present invention wherein a portion of the periphery of the target has been completely removed and a portion of the periphery of the interlayer remains intact such that the flange comprises a portion of the interlayer as well as a portion of the backing plate. [0044] Optionally, the bonded preform can be leveled or flattened, for example, by level rolling before optional partitioning. Flattening the preform can produce a substantially stress-free plate and a nearly planar bonding interface. Preferably, the bonded preform is flattened before the desired cutting pattern is determined, and preferably before the desired cutting pattern is marked on the surface of the bonded preform.

[0045] The method described above permits the formation of large targets or the bonding of multiple targets onto a backing plate in one bonding process and thus achieves a greater output of target materials bonded onto backing plates and further achieves a consistent bonding of the multiple sputtering target assemblies.

[0046] Other embodiments of the present invention will be apparent to those skilled in the art from consideration of the present specification and practice of the present invention disclosed herein. It is intended that the present specification and examples be considered as exemplary only with a true scope and spirit of the invention being indicated by the following claims and equivalents thereof.

Claims

WHAT IS CLAIMED IS:

1. A method of forming a sputtering target assembly, comprising: explosively bonding a target grade plate having a bonding surface and a backing plate member having a bonding surface to form a bonded preform having a bonded target grade plate and a bonded backing plate member; and partitioning said bonded preform to form a plurality of sputtering target assemblies.

2. The method of claim 1, wherein said target grade plate comprises a valve metal.

3. The method of claim 1, wherein said target grade plate comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

4. The method of claim 1, wherein said target grade plate comprises tantalum or an alloy thereof.

5. The method of claim 1, wherein said target grade plate comprises niobium or an alloy thereof.

6. The method of claim 1, wherein said backing plate member comprises tantalum, niobium, titanium, copper, aluminum, or alloys thereof.

7. The method of claim 1, wherein said backing plate member comprises copper or an alloy thereof.

8. The method of claim 1, wherein said target grade plate comprises tantalum or an alloy thereof and said backing member comprises copper or an alloy thereof.

9. The method of claim 1, wherein said backing plate member is explosively accelerated into said target grade plate.

10. The method of claim 1, wherein a bond strength between said target grade plate and said backing plate member at a bond interface of said bonded preform is from about 10,000 p.s.i. to about 75,000 p.s.i.

11. The method of claim 1, wherein said target grade plate has an average grain size of less than about 100 microns and a texture substantially void of (100) textural bands, and wherein said bonded preform has a sputter target having an average grain size of less than about 100 microns and a texture substantially void of (100) textural bands.

12. The method of claim 1 , wherein said bonded preform has a backing plate that has a hardness more than that of said backing plate member.

13. The method of claim 1, further comprising disposing at least one interlayer between a portion of said bonding surfaces wherein said bonded preform has a bonded interlayer.

14. The method of claim 13, wherein said at least one interlayer comprises niobium or an alloy thereof.

15. The method of claim 13, wherein said at least one interlayer comprises tantalum or an alloy thereof.

16. The method of claim 13, wherein said at least one interlayer has a thickness of from about 0.01 to about 0.09 inches.

17. The method of claim 13, wherein said at least one interlayer covers from about 10 to about 100% of said bonding surface of said target grade plate or said backing member.

18. The method of claim 1, further comprising removing at least a portion of a periphery of said bonded target grade plate, said bonded backing plate member, or a combination thereof to form a flange on said sputtering target assembly.

19. The method of claim 13, further comprising removing at least a portion of a periphery of said bonded target grade plate, said bonded backing plate member, said bonded interlayer, or combinations thereof to form a flange on said sputtering target assembly.

20. The method of claim 1, further comprising flattening said bonded preform.

21. The method of claim 1 , wherein said partitioning forms at least one test sample.

22. A sputtering target assembly comprising: a target having a bonding surface; a backing member having a bonding surface; and an interlayer disposed between a portion of said bonding surfaces, wherein said target, said backing member, and said interlayer are explosively bonded together.

23. The sputtering target assembly of claim 22, wherein said target comprises a valve metal.

24. The sputtering target assembly of claim 22, wherein said target comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

25. The sputtering target assembly of claim 22, wherein said target comprises tantalum or an alloy thereof.

26. The sputtering target assembly of claim 22, wherein said target comprises niobium or an alloy thereof.

27. The sputtering target assembly of claim 22, wherein said backing member comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

28. The sputtering target assembly of claim 22, wherein said backing member comprises copper or an alloy thereof.

29. The sputtering target assembly of claim 22, wherein said interlayer comprises niobium or an alloy thereof.

30. The sputtering target assembly of claim 22, wherein said interlayer comprises tantalum or an alloy thereof.

31. The sputtering target assembly of claim 22, wherein said interlayer has a thickness of from about 0.01 to about 0.09 inches.

32. The sputtering target assembly of claim 22, wherein said interlayer covers from about 10 to about 100% of said bonding surface of said target.

33. The sputtering target assembly of claim 22, wherein said interlayer covers from about 10 to about 100% of said bonding surface of said backing member.

34. The sputtering target assembly of claim 22, further comprising a flange comprising a portion of said target, a portion of said interlayer, a portion of said backing member, or any combinations thereof.

35. The sputtering target assembly of claim 22, wherein before said bonding said interlayer is bonded to said target or said backing member.

36. A bonded prefoπn having dimensions sufficient to be divided to form a plurality of sputtering target assemblies, comprising: a target grade plate having a bonding surface; and a backing plate member having a bonding surface, wherein said target grade plate and said backing plate member are explosively bonded together.

37. The bonded preform of claim 36, wherein said target grade plate comprises a valve metal.

38. The bonded preform of claim 36, wherein said target grade plate comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

39. The bonded preform of claim 36, wherein said target grade plate comprises tantalum or an alloy thereof.

40. The bonded preform of claim 36, wherein said target grade plate comprises niobium or an alloy thereof.

41. The bonded preform of claim 36, wherein said backing plate member comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

42. The bonded preform of claim 36, wherein said backing plate member comprises copper or an alloy thereof.

43. The bonded preform of claim 36, wherein said backing plate member is explosively accelerated into said target grade plate.

44. The bonded preform of claim 36, wherein said target grade plate has an average grain size of less than about 100 microns and a texture substantially void of (100) textural bands, and wherein said bonded preform has a sputter target having an average grain size of less than about 100 microns and a texture substantially void of (100) textural bands.

45. The bonded preform of claim 36, wherein a bond strength between said target grade plate and said backing plate member at a bond interface of said bonded preform is from about 10,000 p.s.i. to about 75,000 p.s.i.

46. The bonded preform of claim 36, wherein said bonded prefoπn has a backing plate that has a hardness more than that of said backing plate member.

47. The bonded preform of claim 36, further comprising at least one interlayer disposed between a portion of said bonding surfaces.

48. The bonded preform of claim 46, wherein said at least one interlayer comprises niobium or an alloy thereof.

49. The bonded preform of claim 46, wherein said at least one interlayer comprises tantalum or an alloy thereof.

50. The bonded preform of claim 46, wherein said at least one interlayer has a thickness of from about 0.01 to about .09 inches.

51. The bonded preform of claim 46, wherein said at least one interlayer covers from about 10 to about 100% of said bonding surface of said target grade plate or said backing member.

52. The method of claim 1, wherein a bond strength between said target grade plate and said backing plate member at a bond interface of said bonded preform is from about 29,000 p.s.i. to about 55,000 p.s.i.

53. The method of claim 12, wherein said hardness is at least 10% greater in said backing plate compared to said backing plate member.

54. A bonded preform or target assembly comprising a target and a backing plate bonded together, wherein said bonded preform has a continuous sputter surface area of greater than 1.5 m².

55. The bonded preform or target assembly of claim 54, wherein said sputter surface area is from 1.5 m²to about 10 m².

56. The bonded preform or target assembly of claim 54, wherein said sputter surface area is from about 2 m²to about 6 m².

57. The bonded preform or target assembly of claim 54, wherein said target and said backing plate are bonded together by molecular bonding.

58. A bonded preform or target assembly comprising a target and a backing plate explosively bonded together, wherein said bonded preform has a sputter surface area of greater than 400 cm².

59. The bonded preform or target assembly of claim 58, wherein said sputter surface area is from about 500 cm² to about 10 m².

60. A bonded preform or target assembly comprising a target and a backing plate bonded together, wherein said bonded preform has a rectangular dimensions of 1.5m or greater x 1.5m or greater or a circular diameter of at least 1.5m.

61. A bonded preform or target assembly comprising a target and backing plate explosively bonded together, wherein said bonded preform has a continuous sputter surface area of 400 cm" or greater.

62. The bonded preform or target assembly of claim 61, further comprising an interlayer located between said target and backing plate.

63. The bonded preform or target assembly of claim 54, further comprising an interlayer located between said target and backing plate.

64. The bonded preform or target assembly of claim 54, wherein said target comprises a valve metal.

65. The bonded preform or target assembly of claim 54, wherein said target comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

66. The bonded preform or target assembly of claim 54, wherein said target comprises tantalum or an alloy thereof.

67. The bonded preform or target assembly of claim 54, wherein said target comprises niobium or an alloy thereof.

68. The bonded preform or target assembly of claim 54, wherein said backing plate member comprises tantalum, niobium, titanium, copper, aluminum, or alloys thereof.

69. The bonded preform or target assembly of claim 54, wherein said backing plate member comprises copper or an alloy thereof.

70. The bonded preform or target assembly of claim 54, wherein said target grade plate comprises tantalum or an alloy thereof and said backing member comprises copper or an alloy thereof.

71. The bonded preform or target assembly of claim 58, wherein said target grade plate comprises a valve metal.

72. The bonded preform or target assembly of claim 58, wherein said target grade plate comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

73. The bonded preform or target assembly of claim 58, wherein said target grade plate comprises tantalum or an alloy thereof.

74. The bonded preform or target assembly of claim 58, wherein said target grade plate comprises niobium or an alloy thereof.

75. The bonded preform or target assembly of claim 58, wherein said backing plate member comprises tantalum, niobium, titanium, copper, aluminum, or alloys thereof.

76. The bonded preform or target assembly of claim 58, wherein said backing plate member comprises copper or an alloy thereof.

77. The bonded preform or target assembly of claim 58, wherein said target grade plate comprises tantalum or an alloy thereof and said backing member comprises copper or an alloy thereof.

78. The bonded preform or target assembly of claim 60, wherein said target grade plate comprises a valve metal.

79. The bonded preform or target assembly of claim 60 wherein said target grade plate comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

80. The bonded preform or target assembly of claim 60, wherein said target grade plate comprises tantalum or an alloy thereof.

81. The bonded preform or target assembly of claim 60, wherein said target grade plate comprises niobium or an alloy thereof.

82. The bonded preform or target assembly of claim 60, wherein said backing plate member comprises tantalum, niobium, titanium, copper, aluminum, or alloys thereof.

83. The bonded preform or target assembly of claim 60, wherein said backing plate member comprises copper or an alloy thereof.

84. The bonded preform or target assembly of claim 60, wherein said target grade plate comprises tantalum or an alloy thereof and said backing member comprises copper or an alloy thereof.

85. The bonded prefoπn or target assembly of claim 61, wherein said target grade plate comprises a valve metal.

86. The bonded preform or target assembly of claim 61, wherein said target grade plate comprises tantalum, niobium, cobalt, titanium, copper, aluminum, or alloys thereof.

87. The bonded preform or target assembly of claim 61, wherein said target grade plate comprises tantalum or an alloy thereof.

88. The bonded preform or target assembly of claim 61, wherein said target grade plate comprises niobium or an alloy thereof.

89. The bonded preform or target assembly of claim 61, wherein said backing plate member comprises tantalum, niobium, titanium, copper, aluminum, or alloys thereof.

90. The bonded preform or target assembly of claim 61, wherein said backing plate member comprises copper or an alloy thereof.

91. The bonded preform or target assembly of claim 61, wherein said target grade plate comprises tantalum or an alloy thereof and said backing member comprises copper or an alloy thereof.

92. The bonded preform or target assembly of claim 63, wherein said interlayer is formed by striping material from an anvil and depositing said material at the bond interface using an explosion bonding plasma jet.

93. The bonded preform or target assembly of claim 92, wherein at least one coating of a bond enhancing material is applied to the anvil.