Improvement of Negative Bias Temperature Instability by Stress Proximity Technique

The stress proximity technique (SPT) is found to improve negative bias temperature instability (NBTI) in p-channel metal-oxide-semiconductor field-effect transistors significantly. A first-principles calculation is carried out to examine the effect of strain on NBTI, and a process simulation is conducted to determine the change in stress profile in the device induced by SPT. The first-principles calculation shows that a larger strain leads to higher NBTI degradation. On the other hand, the process simulation shows that, although the compressive stress along the channel direction is enhanced by SPT, the vertical tensile stress is greatly reduced by SPT. The larger reduction in stress along the vertical direction is believed to be responsible for the improvement of NBTI by SPT.