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ABSTRACT: The application of low-frequency charge pumping to obtain
near-interface, or bulk trap densities, on thin stacked gate dielectrics
is studied. A review of the theory governing the low-frequency charge
pumping technique, developed to extract bulk trap densities from
metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated
with thick SiO<sub>2</sub> dielectrics, is given. In this study, the
technique is applied to a series of n-channel MOSFETs fabricated with
stacked gate dielectrics. The dielectric stacks were comprised of rapid
thermal oxide (RTO) interface layers and rapid thermal chemical vapor
deposited (RTCVD) oxynitride layers, which incorporated varying
concentrations of nitrogen. The effect of DC tunneling currents on the
technique is studied, and a procedure to remove these components from
the measured substrate current is outlined. Distortions in the
experimentally measured charge pumping current plotted as a function of
gate bias is modeled and found to be due to the contribution of bulk
traps. Finally, the limitations of applying a model that was originally
developed for thick SiO<sub>2</sub> dielectrics to thin stacked gate
dielectrics are discussed
IEEE Transactions on Electron Devices 01/2002; · 2.32 Impact Factor
