Plasma charging damage on MOS devices with gate insulator of high-dielectric constant material

Plasma charging effects on the gate insulator of high-dielectric constant ( k) material in MOS devices deserve to be investigated because of different trap-assisted conduction mechanisms. Plasma-induced degradation in gate-lea kage current and time to breakdown is clearly observed in this work. MOS de vice with Si3N4 film seems to have smaller degradation of gate-leakage curr ent while it suffers shorter time to breakdown as compared to Ta2O5 samples . For devices with Ta2O5 film, a larger physical thickness suffers more rel iability degradation from plasma charging damage because of the richer trap s. Thus, a smaller physical thickness of high-k dielectric film is favorabl e for sub-micron MOS devices of ULSI application.