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

摘要

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