Electron Trapping and Detrapping in 8 nm-Thick Gate-Oxide of p+ Poly-Gate p-MOSFET´s

The hot-carrier-reliability of pure and nitrided tiin gate-oxides (8nm-thick) for p-MOSFET´s is investigated with DC stress experiments. A peculiar degradation mode is observed in these 8nm-thick gate-oxides where reducing the channel-width enhances a turn-around phenomenon observed in the degradations of the transistor parameters. This effect is explained by the field-assisted detrapping of electrons leaving a large number of donor-like interface traps which decrease the drain-current. Detrapping experiments show that a field of about 8MV/cm is required for a fast and complete detrapping even though detrapping begins to occur at fields as low as 4MV/cm.