Comparative Study of Plasma-Charging Damage in High-$k$ Dielectric and p--n Junction and Their Effects on Off-State Leakage Current of Metal--Oxide--Semiconductor Field-Effect Transistors

概要

論文の詳細を見る
Plasma-induced charging damage (PCD) to a metal--oxide--semiconductor field-effect transistor (MOSFET) with a high-$k$ dielectric was studied in detail using a capacitively coupled plasma reactor for various exposure times. From the drain current versus gate voltage characteristics, we observed the threshold voltage shift ($\Delta V_{\text{th}}$) and the increase in reverse-leakage current ($I_{\text{j}}$) at the n+/p junction in plasma-exposed n-channel MOSFETs. The observed $\Delta V_{\text{th}}$ in the negative direction was due to positive trap-site creation in the high-$k$ dielectric. The combined effect by PCD increased off-state leakage current ($I_{\text{off}}$) in n-channel MOSFETs, however, the $I_{\text{j}}$ increase was found to be dominant in the $I_{\text{off}}$ increase. By employing a capacitance-measurement technique, we clarified that the $I_{\text{j}}$ considerably was increased at the junction by PCD, whereas the maximum capacitance at the junction in accumulation decreased. We also identified that the generated defect site density ($n_{\text{d}}$) at the junction induces the observed $I_{\text{j}}$ increase as a trap-assist tunneling site.
2011-08-25