Accurate circuit performance prediction model and lifetime prediction method of nbt stressed devices for highly reliable ulsi circuits

An accurate circuit performance prediction model and a device lifetime prediction method of negative bias temperature (NBT) stressed devices are proposed in this paper. The proposed model is constituted of a threshold voltage (V
_th
) shift and a drain current (I
_D
) reduction. The models can directly link the electrical characteristics degradation to the circuit simulation, thus enable us to design highly reliable ULSI circuits. The circuit performance prediction is confirmed by the experimental data of the oscillation frequency degradation and waveform variation of ring oscillator. The simulation results are in good agreement with the experimental results. Since only a suitable acceleration method allows us to develop the accurate models, the new negative bias temperature instability (NBTI) acceleration method using cold-holes is also developed. The very small saturation value of V
_th
shift (<10mV) is observed. The detail of this physics is discussed in this paper. Finally, we demonstrate the accurate NBTI lifetime prediction using the new method