A Unified TDDB Model for BEOL Dielectrics of Various Structures and Thick FEOL Dielectrics

Abstract

The time-dependent dielectric breakdown (TDDB) of the back-end of line (BEOL) dielectrics has been revisited to clarify the breakdown (BD) mechanism. It is shown that a stress voltage-independent carrier fluence to BD (QBD) is the essential mechanism when one accounts for only the current component contributing to BD. The coexistence of current components that do not contribute to BD such as the transient charging current previously caused us to misunderstand the mechanism. Furthermore, the constant-QBD mechanism is consistent with the BD mechanisms proposed for thick front-end of line (FEOL) silicon dioxide (SiO2)-based gate dielectric films as well as the silicon nitride (Si3N4) metal-insulator-metal (MIM) capacitors. Thus, this model unifies the TDDB models for BEOL dielectrics of various thicknesses and structures and also unifies the TDDB models for BEOL and thick FEOL dielectrics.