Ab Initio Simulations of Low-K and Ultra Low-K Dielectric Interconnects

Ab initio molecular dynamics simulations were carried out to study low-k/ultra low-k dielectric systems comprising Cu/Ta/SiLK-like polymer. A study of the motion of single metal atoms of Cu and Ta in the SiLK-like polymer showed that Cu atom motions are effected by jumps between cavities inside the polymer and that Ta is more sluggish than Cu not only because of its larger mass but also because of stronger affinity to the polymer. It was also found that crosslinking of the polymer did not affect the motion of the metal atoms. Simulations of deposition showed that a thin Ta diffusion barrier does not have good structural integrity to prevent Cu-diffusion when directly deposited onto the SiLK; the barrier performance was greatly improved after introducing a Si-based film between the Ta and SiLK.