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

The effect of fast components in the thresholdvoltage shift (Delta Vth) 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 Delta Vth (Delta V-th,V- fast,V- ini.) does not contribute to long-term device degradation under operating voltage conditions. Therefore, Delta Vth is corrected by eliminating the initial Delta V-th,V-fast,V-ini.. With this adjustment, the effect of measurement time (tm) on the corrected Delta Vth (Delta V-th,V- corr.) is negligible. However, compared with the lifetime estimates made using Delta Vth, corr., the dc measurements still tend toward overestimation under low voltage stress because of the Delta V-th,V- fast,V- str. component induced by stress (not the initial Delta V-th,V- fast,V- ini.). In conclusion, it may be stated that the Delta V-th,V- fast,V- str. component could play a critical role in BTI tests conducted under operating voltage conditions.