Abstract
In ultralow-
k
dielectric systems, the porous dielectrics are normally sealed by a SiC film before the deposition of a Ta diffusion barrier layer. However, the Ta barrier effects are negated when the SiC films are fabricated by plasma-enhanced chemical vapor deposition (PECVD). Through large scale
ab initio
molecular dynamics simulations, the authors found that the barrier degradation is due to H atoms introduced during PECVD. The H impurities diffuse into and transform an otherwise dense Ta layer into a loose amorphous phase which is ineffective as a diffusion barrier.