TDDB degradation analysis using Ea of leakage current for reliable porous CVD SiOC(k=2.45)/Cu interconnects

Abstract

TDDB (time dependent dielectric breakdown) degradation mechanism of Cu damascene interconnects was investigated based on the results SiO/sub 2/ ILD. Cu diffusion can be analyzed by Ea(activation energy) variation of the leakage current. In the SiO/sub 2/ ILD, the lifetime is determined by Cu ion diffusion at the interface between diffusion barrier (DB) SiC and SiO/sub 2/ ILD. Cu diffusion induces Ea lowering of the leakage current, and it results in an increase of Poole-Frenkel and Schottky emission current through DB-SiC. On the other hand, the dielectric breakdown induced after a decrease in the leakage current in the porous-SiOC ILD. It is caused by the electric charge injection, not the Cu ion diffusion, at the interface on the porous-SiOC. It is important to form the rigid interface without any damage. Optimized DB-SiC process and hard mask SiO/sub 2/ protecting porous-SiOC improved the TDDB lifetime.