Gap-filling of Cu Employing Sustained Self-Sputtering with Inductively Coupled Plasma Ionization

Copper filling of high aspect-ratio gaps has been investigated systematically using sustained self-sputtering with ICP ionization. In order to understand gap-filling characteristics, deposition and/or resputtering rates have been measured as a function of the substrate bias, inductively coupled plasma (ICP) power, and the incident angle of ions to the substrate. Since Ar ions are excluded from the plasma, considerable improvement of the bottom coverage has been achieved with proper substrate biasing. This paper also illustrates both the limiting problems and the possibility of the high aspect-ratio hole filling by this method.