Comparison of channel current and drain avalanche current-induced hot-carrier effects in MOSFET´s

Hot-carrier effects induced by the channel current and the drain avalanche current in short-channel MOSFET´s are investigated and compared by characterizing the substrate current at different stages of stress. Not only does the drain avalanche stress (DAS) degrade devices much faster than the triode region stress (TCS) does, but the substrate current versus the stress time shows a characteristic difference between the DAS mode and the TCS mode. The difference is that the DAS mode involves localized interface trap generation near the drain and more widely distributed hole trapping in the oxide, while in the TCS mode the mechanism is mainly localized electron trapping in the oxide.