Koen Strijckmans

A time-dependent model for reactive sputter deposition

A time-dependent, spatially resolved model (RSD2013) for dc reactive magnetron sputtering is proposed. The model includes several processes such as reactive gas chemisorption on the target and the substrate, direct and knock-on implantation of reactive species in the target, subsurface compound formation in the target, the deposition of sputter material on the substrate and redeposition of sputtered material back on to the target. A full derivation and motivation of the model is given. This formulation of the model is contained within the software RSD2013, a user-friendly simulation tool for the reactive sputter process. To demonstrate this tool, a time-dependent simulation of a realistic system with an increasing number of available RSD2013 options is discussed.

Perspective: Is there a hysteresis during reactive High Power Impulse Magnetron Sputtering (R-HiPIMS)?

This paper discusses a few mechanisms that can assist to answer the title question. The initial approach is to use an established model for DC magnetron sputter deposition, i.e., RSD2013. Based on this model, the impact on the hysteresis behaviour of some typical HiPIMS conditions is investigated. From this first study, it becomes clear that the probability to observe hysteresis is much lower as compared to DC magnetron sputtering. The high current pulses cannot explain the hysteresis reduction. Total pressure and material choice make the abrupt changes less pronounced, but the implantation of ionized metal atoms that return to the target seems to be the major cause. To further substantiate these results, the analytical reactive sputtering model is coupled with a published global plasma model. The effect of metal ion implantation is confirmed. Another suggested mechanism, i.e., gas rarefaction, can be ruled out to explain the hysteresis reduction. But perhaps the major conclusion is that at present, there...

The existence of a double S-shaped process curve during reactive magnetron sputtering

The four dimensional parameter space (discharge voltage and current and reactive gas flow and pressure) related to a reactive Ar/O2 DC magnetron discharge with an aluminum target and constant pumping speed was acquired by measuring current-voltage characteristics at different oxygen flows. The projection onto the pressure-flow plane allows us to study the well-known S-shaped process curve. This experimental procedure guarantees no time dependent effects on the result. The obtained process curve appears not to be unique but rather two significantly different S-shaped curves are noticed which depend on the history of the steady state target condition. As such, this result has not only an important impact on the fundamental description of the reactive sputtering process but it can also have its consequences on typical feedback control systems for the operation in the transition regime of the hysteresis during reactive magnetron sputtering.