Cu Barrier Properties of Cluster-Preforming-Deposited Amorphous -$mathrm{WSi}_{n}$Films Depending on Composition$n$

摘要

The amorphous$mathrm{WSi}_{n}$film composed of W-atom-encapsulated$mathrm{Si}_{n}$cage clusters has barrier properties against Cu. Thermal stability of the double layers of$mathrm{Cu}/mathrm{WSi}_{n}$was investigated for various values of$n=5-13$. It was revealed that the diffusion of Si atoms to Cu is most suppressed when$n$is 12. The estimated TDDB lifetime for Cu/WSi12 MOS capacitors exceeds 10 years at 100°C under 5 MV/cm stress. This is because the constituent W-atom-encapsulated Si12 cluster has the most stable cage structure, giving excellent stability and capturing ability of Cu ions to the film with$n=12$.