A NOVEL STACK STRUCTURE TO IMPROVE THE DEGRADATION OF W-POLYCIDE GATED MOS DEVICE WITH UNDOPED A-SI HEAVILY-DOPED POLY-SI MULTILAYER

An original structure with undoped amorphous silicon (a-Si)/heavily-do ped polysilicon stacked layer is reported in this paper, By this struc ture, it can prevent the deterioration of the gate oxide caused by the fluorine ions in conventional tungsten-polycide (W-polycide) gated MO S devices. The relationship between the thickness of the stacked a-Si layer and the quality of the gate oxide is also investigated, With thi s W-silicide/a-Si/polysilicon stack structure, a lower sheet resistanc e of the W-polycide can also be obtained.