Ultra thin diffusion barriers for Cu interconnections at the gigabit generation and beyond

✍ Scribed by F. Braud; J. Torres; J. Palleeau; J.L. Mermet; C. Marcadal; E. Richard

• Book ID: 104306221
• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 410 KB
• Volume: 33
• Category: Article
• ISSN: 0167-9317
• DOI: 10.1016/s0167-9317(96)00057-3

✦ Synopsis

The reliability of copper interconnection depends on the barrier effectiveness of conductive or non-conductive layers to block any copper motion. The conductive barrier materials currently used in AI-based interconnections -Ti, TiN, W and nitrided W -have been investigated as barrier against copper diffusion. The barrier thickness must be as thin as possible to achieve negligible barrier contribution to the total line resistance. Electrical tests C-V on MOS capacitors were performed to assess the rate of electrically active copper impurities transported through the barrier layer. The stability of a copper/barrier/ oxide/silicon structure was studied under thermal stress with or without bias. For back-end process annealing performed under vacuum, the copper diffusion was shown to be limited, and very thin barrier films were shown to be effective in preventing copper diffusion.