BEOL dielectric processing for Cu-Low k nano interconnect-impact of plasma CVD initial transient phenomena (ITP)

Abstract

The Initial Transient Phenomena (ITP) during plasma CVD, its impact in nano thick film fabrication and methods to mitigate any negative impact from this phenomenon are presented in this paper. Plasma deposited dielectrics such as SiCOH, SiNx, SiCNx are regularly used for Cu low-k interconnect fabrication. For lightly porous low-k SiCOH films deposited with organosilicon and oxygen precursors, an initial C-Rich SiCOH is typically deposited at the interface due to ITP and the intrinsic plasma deposition chemistry. This carbon rich interface will weaken the film's adhesion to the underlying surface and degrade the electrical properties of the nano-thiek SiCOH dielectric. For SiCNx or SiNx dielectric films, local and global ITP charging effects on blanket and patterned surfaces have significant impacts on film's quality and thickness control. Various novel process modifications were developed to mitigate ITP and to improve the plasma CVD dielectric film.