Cost-effective and High Performance Cu Interconnects (keff=2.75) with Continuous SiOCH Stack Incorporating a Low-k Barrier Cap (k=3.1)

Cost-effective and high performance Cu interconnects with k
_eff
=2.75 were developed in single-step continuous SiOCH stack incorporating a low-k barrier cap of silica-amorphous-carbon-composite (SACC)-SiOCH film (k=3.1,E=20 GPa) with anti-oxidation surface treatment of Cu. The SACC-cap was effective to improve the adhesion strength besides the Cu diffusion barrier property. The continuous SiOCH stack by plasma co-polymerization (PcP) process demonstrated 11.7 % lower inter-layer capacitance and five times longer electro-migration life-time, as compared with a conventional multi-step SiOCH stack on SiCN cap (k=4.9). The continuous SiOCH stack incorporating the SACC-cap satisfies high performance and high reliability by simple low-cost process, applicable for leading-edge ULSIs as well as low-cost mobile applications.