In the field of sputtering application, the sputtering target assembly typically has a sputtering target and a backing plate. For example, a metal target or blank (e.g., tantalum, titanium, aluminum, copper, cobalt, tungsten, etc.) is bonded to a backing plate, such as a backing plate flange assembly such as copper, aluminum, or an alloy thereof. In order to achieve good thermal and electrical contact between the target and the backing board, these parts are usually attached to each other by soldering, brazing, diffusion bonding, claming, and by epoxy adhesives. However, the sputtering target assembly combined by the method at high temperatures can warp the assembly during use, which affects the performance of the sputtering target assembly, especially when there is a large difference between the coefficient of thermal expansion of the target and the backing plate. Moreover, the different thermal expansions that occur between the target material and the backing material when the bonding is completed at high temperatures by soldering, brazing, or diffusion bonding produce very high levels of mechanical stress in the metal body. Mechanical stress often causes the target assembly to flex and can cause binding failure, separating the target from the backing plate.
The combination method also increases weight and creates the risk of stripping the target assembly while in use. This divestiture risk is more likely due to the continuous progress of the industry using increasingly larger targets. In addition, the high temperatures associated with some conventional binding methods can lead to undesired grain growth in the target metal.
The sputtering target assembly comprises two component components, namely, the backing plate assembly and the sputtering target assembly. The sputtering target component and backing plate may be of any suitable target grade and backing plate grade material. Examples of target materials to be combined by the method of the invention include, but are not limited to, tantalum, niobium, cobalt, titanium, copper, aluminum, and their alloys, such as the alloys described above. Examples of backing plates include, but are not limited to, copper, or copper alloys, tantalum, niobium, cobalt, titanium, aluminum, and their alloys, such as TaW, NbW, TaZr, NbZr, TaNb, NbTa, TaTi, NbTi, TaMo, NbMo, etc. There are no restrictions on the type of material used for sputtering targets and backing boards. The thickness of the backing and target material may be any suitable thickness for forming the sputtering target. Alternatively, the backing board and the target material or other metal plates to be bonded to the backing board may be of any suitable thickness for the desired application. Examples of suitable thicknesses for backing boards and target materials include, but are not limited to, a backing board thickness of approximately 0.25 or less to approximately 2 inches or greater, and a target thickness in a range of approximately 0.060 inches to approximately 1 inch or greater. In the present invention, the target material to be incorporated into the backing board may be a conventional target grade material, as described in United States Patent No.6,348,113, the entirety of which is herein introduced for reference. The sputtering target may also have a sandwich as is commonly used in industry. Moreover, the sputtering target may be a hollow cathode magnetron sputtering target, and may be other forms of sputtering target, such as a planar magnetron assembly with a fixed or rotating permanent or electromagnetic body. Purity, construction, and/or particle size and other parameters including dimensions are not critical to the present invention.
