Highly reliable Enhanced Nitride Interface (ENI) process of barrier Low-k using absorption-free Ultra-Thin SiN (UT-SiN)

A highly reliable Enhanced Nitride Interface (ENI) process of barrier Low-k using an Ultra-Thin SiN (UT-SiN) has been developed for 40-nm node and beyond. The UT-SiN (3nm) has a good thickness uniformity and a good stability against absorption. By using this technique, a lower effective k and good via yields were obtained. In addition, 5x via electro-migration (EM) improvement, 50x TDDB and no SIV failure by 1000h were obtained in comparison to the conventional SiCN bi-layer process. And the ENI was analyzed by XPS and TOF-SIMS. According to these analyses, the mechanism for performance enhancement is proposed.