Two-Pulse $C$–$V$ : A New Method for Characterizing Electron Traps in the Bulk of $ \hbox{SiO}_{2}/\hbox{high-}\kappa$ Dielectric Stacks

$\hbox{SiO}_{2}/\hbox{high-}\kappa$ dielectric stack is a candidate for replacing the conventional $\hbox{SiO}_{2}$-based dielectric stacks for future Flash memory cells. Electron traps in the high-$ \kappa$ layer can limit the memory retention via the trap-assisted tunneling, and there is a pressing need for their characterization. A new two-pulse $C$ –$V$ measurement technique is developed in this letter, which, for the first time, allows us to probe the discharge of electron traps throughout the $\hbox{SiO}_{2}/\hbox{high-}\kappa$ stack. It complements the charge pumping technique, which can only probe near-interface traps. It is demonstrated that a large number of electron traps, indeed, exist in the bulk of high-$\kappa$ layer. Bulk electron traps also have different discharge characteristics from those near the $\hbox{SiO}_{2}/\hbox{high-}\kappa$ interface.