Effect of reverse substrate bias on ultra-thin gate oxide n-MOSFET degradation under different stress modes

Degradation of ultra-thin gate oxide n-MOSFET with halo structure is studied under different stress modes with the increase of reverse substrate bias. The variation of device degradation is characterized by monitoring the substrate current during stress. When the gate voltage is smaller than a critical value, the device degradation first decreases and then increases with the increase of reverse substrate voltage; otherwise, the device degradation increases continually. The critical gate voltage can be determined by measuring the substrate current variation with the increase of reverse substrate voltage.