Effect of CH4 Plasma on Porous Dielectric Modification & Pore Sealing for Advanced Interconnect Technology Nodes

Patterning and ashing are known to be critical steps to the integration of porous ultra low-k dielectrics in interconnects, mainly due to low-k damage during these processes. In this paper, we investigate the impact of a new methane based ash chemistry on the sidewall modification of the porous dielectric. Physical and electrical characterizations of the integrated low-k evidence a sealing effect of CH4 plasma on dielectric sidewalls as well as a gain in reliability compared to other known plasma chemistries. The impact of CH4 chemistry on leakage mechanism is also investigated.