A model for post-CMP cleaning effect on TDDB

Abstract

For 45 nm and beyond, direct polished porous type ultra low-K film (ULK) is integrated in Cu interconnects. Post-cleaning of Cu CMP effect on Time dependent dielectric breakdown (TDDB) was investigated. Cu ions remaining on dielectrics and Cu roughness are found as two dominate factors at different clean time region. High Cu roughness induced capping layer seam results in the degradation of TDDB. A statistical model, said weak element model, was proposed to illustrate the correlation of Cu roughness on TDDB as well.