An Investigation of Field Reduction Effect on NBTI Parameter Characterization and Lifetime Prediction Using a Constant Field Stress Method

Abstract

The impact of the field reduction effect on negative bias temperature instability (NBTI) parameter characterization and lifetime prediction was quantitatively studied in p-MOSFETs with a sub-1 nm equivalent oxide thickness (EOT). By comparing NBTI results under constant field stress and constant voltage stress, the field reduction effect was found to become severer at higher VG-STR and ${T}$ and cause a reduction in the voltage acceleration factor (VAF) at higher VG-STR and a reduction in activation energy EA at higher ${T}$ under constant voltage stress. To accurately evaluate NBTI lifetime, a modified NBTI model with field reduction correction (FRC) was proposed, and the 10-year NBTI degradation of a 32-stage ring oscillator was simulated. The results showed that the conventional model without including FRC had a worse prediction capability and overestimated frequency degradation for a ring oscillator. It is necessary to use an NBTI model with FRC for NBTI lifetime prediction of devices with a sub-1 nm EOT.