Latent damage generation in thin oxides of metal-oxide-semiconductor devices under high-field impulse stress and damage characterization using low-frequency noise measurement

Latent damage generation in thin oxides of metal-oxide-semiconductor (MOS) devices, caused by high-field impulse or electrostatic discharge (ESD) stress applied to the gate electrode, can lead to increased trap generation during subsequent hot-carrier stressing. However, the charge-to-breakdown (Q(bd)) of such impulse prestressed devices is not significantly affected by the latent damage, and hence it is difficult to characterize such damage using Q(bd) measurements. Monitoring of the latent damage can be carried out by detecting the change in an appropriate electrical parameter of the device or by extracting die generated interface states and oxide trap charges. However, such electrical measurements have their own limitations. It was found that low-frequency noise measurement is a more sensitive method than the above-mentioned electrical measurements for characterizing the ESD stress-induced latent damage in thin oxides.