On the electrical stress-induced oxide-trapped charges in thin HfO2∕SiO2 gate dielectric stack

Abstract

Oxide charge buildup and its generation kinetics during constant voltage stress in TaN∕HfO2∕SiO2∕p-Si structures have been experimentally investigated. From the oxide charge relaxation experiments, nature and energy location of the as-fabricated intrinsic hole traps in the gate stack have also been determined. Our measurement results indicate that the dispersive proton transport through the interfacial SiO2 contributes larger than hole trapping in positive charge buildup in the stack. From the bias temperature stress measurement results in both control oxide and HfO2∕SiO2 stacks, we have identified overcoordinated [Si2=OH]+ centers as the proton-induced defects located in the interfacial SiO2 layer of the stack. Finally, an empirical equation is proposed to explain the stress-induced oxide positive charge buildup.