Extendibility of PVD barrier/seed for BEOL Cu metallization

Abstract

This paper describes a new Physical Vapor Deposition (PVD) metallization scheme that shows a better extendibility for future technology nodes as compared to the conventional scheme. In addition to reducing thicknesses of both the diffusion barrier and the copper seed layer [1], this new scheme also features a sacrificial process (also called barrier-first process [2]), a via-punch through process [3,4] and a simultaneous preclean with metal neutral deposition process [5,6], Significant metal line and via contact resistance decrease was observed with equal or better reliability. Impact of sputter etch integration scheme on electrical yield and reliability is also reported. The new sputter scheme decreases contact resistance at via/interconnect interface and can offset the one resulted from dimension scaling and thus extends PVD metallization usefulness for future technologies. © 2005 IEEE.