Investigation of CVD SiCOH low-k time-dependent dielectric breakdown at 65nm node technology

With wide application of low-k dielectric materials in multilevel VLSI circuits, the long-term reliability of such materials is rapidly becoming one of the most critical challenges for technology development. Among all the reliability issues, low-k time dependent dielectric breakdown (TDDB) is commonly considered a crucial problem. In this study, the effect of process variations on chemical-vapor deposited (CVD), carbon doped oxide dielectrics comprised of Si, C, O, and H (SiCOH) TDDB degradation at the 65 nm node is investigated. SiCOH TDDB is found to be sensitive to all aspects of integration. Based on extensive experimental data, an electrochemical-reaction-induced, three-step degradation model is proposed to explain the SiCOH dielectric breakdown process. Finally, we demonstrate that with careful process and materials optimization, a superior performance at the 65 nm node can be achieved for 300 mm fabrication. The projected lifetime, based on a conservative modeling approach and aggressive test structure, is far beyond the most stringent reliability target.