Gayatri Rane, Philipp Dürrenfeld, Uwe Krause, Advanced Energy Industries, Karlstein am Main, Germany
Bipolar pulsed sputter deposition provides a robust method for depositing insulating coatings like oxides and nitrides. For several years, both sine-wave and square-wave generators have been utilized for these processes. Different applications demand stringent and distinct coating requirements, and pulse mode provides an additional variable enabling a user to optimize film microstructure and thereby film properties. This presentation shows a comparative study of three types of bipolar pulsed modes: symmetric sinusoidal pulsing, symmetric square pulsing and the new asymmetric square pulsing mode called dynamic reverse pulsing. The three modes were tested on reactive sputter deposition of silicon nitride films in an industrial drum coater. The aim is to provide a comprehensive understanding of the different modes and their influence on the film properties in terms of deposition rate, heat load at the substrate, residual stress and optical properties. We show that the different pulse modes have inherent differences in plasma behavior and we outline their benefits.