Influence of mobility model on extraction of stress dependent source–drain series resistance

The extraction of the parasitic source–drain series resistance after stress is a significant challenge, which has not been reported for channel lengths below 0.5 μm. Methods proposed until now yield a reducing series resistance behaviour for such channel lengths, contrary to expectation. We demonstrate that the underlying cause of this phenomenon is due to modification of mobility behaviour under stress. A new methodology for monitoring the time dependent progression of series resistance and mobility degradation for stress conditions varying from hot carriers to Negative Bias Temperature is proposed. A new threshold voltage model separating the effects of damaged and undamaged portions of a stressed device is also demonstrated.