Abstract: A sputtering target assembly is fabricated by diffusion bonding a target material plate to a backing plate. The plates are cleaned in a vacuum environment, and an interlayer is formed on one or more of the plates. The plates are then joined under heat and pressure, before an oxide layer can form on the joining surfaces of the plates. The plates may be sequentially processed through cleaning, interlayer deposition, and bonding chambers, all with vacuum environments, to form the finished part, or, a single chamber may be used to provide the cleaning, interlayer deposition and bonding functions.