Extendibility of PVD barrier/seed for BEOL Cu metallization

The 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 the thicknesses of both the diffusion barrier and the copper seed layer (Yang, C.-C. et al., MRS Adv. Metallization Conf., p.213, 2004), this new scheme also features a sacrificial process (also called barrier-first process) (Alers, G., IEEE Int. Interconnect Technology Conf., 2003), a via-punch through process (Edelstein, D. et al., IEEE Int. Reliability Physics Symp., p.316, 2004; Kuma, N. et al., MRS Adv. Metallization Conf, p.247, 2004) and a simultaneous preclean with a metal neutral deposition process (Yang et al., US Patent 6,784,105, 2004; Uzoh, C. et al., US Patents 5,930,669, 1999; 5,933,753, 1999; 6,429,519, 2002). Significant metal line and via contact resistance decrease was observed with equal or better reliability. The impact of a sputter etch integration scheme on electrical yield and reliability is also reported. The new sputter scheme decreases contact resistance at the via/interconnect interface and can offset the one resulting from dimension scaling and thus extends PVD metallization usefulness for future technologies.