Mechanisms for compositional variations of coatings sputtered from a WS 2 target

Magnetron sputtering from compound targets is widely used for the deposition of compound films since it is easy to scale up and it exhibits a high reproducibility. Controlling film stoichiometry is crucial for obtaining films with desired properties. However, the process is rather complex and sputtering from a compound target frequently results in film compositions that deviate significantly from that of the target. This is due to a number of effects related to the nature of the sputtering process which include preferential re-sputtering due to energetic particle bombardment at the substrate, different take-off angles, scattering in the gas phase, and different sticking coefficients.