High power impulse magnetron sputtering discharge

TLDR

HiPIMS is a recently developed, scalable ionized physical vapor deposition technique that has become an established, industrially applicable plasma‑based sputtering method. The authors review the development of HiPIMS and the mechanisms governing its discharge properties. HiPIMS employs high‑power, low‑duty‑cycle pulses that generate a highly ionized, dense plasma, and the authors discuss the pulsed power supply, measured plasma parameters, deposition rates, and models such as the material‑pathway and ionization‑region models. HiPIMS produces a highly ionized, dense plasma that enables precise control of film growth and offers a significant advantage over conventional dc magnetron sputtering, which mainly yields neutral vapor.

Abstract

The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.