Effect of Fast Components in Threshold-Voltage Shift on Bias Temperature Instability in High-$k$ MOSFETs

The effect of fast components in the threshold-voltage shift (¿V
_th
) induced by electrical stress on the lifetime of bias temperature instability (BTI) is investigated in metal-oxide-semiconductor field-effect transistors with high-k gate dielectrics using dc and pulsed measurements. The empirical results confirm that the initial fast ¿V
_th
(¿V
_th,fast,ini
.) does not contribute to long-term device degradation under operating voltage conditions. Therefore, ¿V
_th
is corrected by eliminating the initial ¿V
_th,fast,ini
. With this adjustment, the effect of measurement time (t
_m
) on the corrected ¿V
_th
(¿V
_th,corr
.) is negligible. However, compared with the lifetime estimates made using ¿V
_th,corr
., the dc measurements still tend toward overestimation under low voltage stress because of the ¿V
_th,fast,str
. component induced by stress (not the initial ¿V
_th,fast,ini
.)In conclusion, it may be stated that the ¿V
_th,fast,str
. component could play a critical role in BTI tests conducted under operating voltage conditions.