The role of the erosion groove during reactive sputter deposition

Target erosion and the formation of an erosion groove are typical features of planar magnetron sputtering. The deepening of the erosion groove results in a modification of the process parameters, and as a consequence of the working conditions during reactive magnetron sputter deposition. This is noticed when the reactive gas partial pressure, or any other deposition parameter, as a function of the reactive gas flow is measured. These processing curves, which show hysteresis behavior, indicate that a lower oxygen flow is needed to oxidize or poison the target when the erosion groove is deeper. In principle, several reasons for this change can be given. Analysis of the shape of the erosion groove and the deposition flux profile shows that these two parameters do not change as a function of the erosion groove depth, and therefore they can be ruled out as possible reasons for the noticed behavior of the hysteresis experiments. A combination of experiments with different target thicknesses and simulations shows that the only parameter responsible for these changes is the discharge voltage, which defines the sputter yields of both the compound formed on the target surface and the metallic target material.