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

Abstract

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-leakage current and time to breakdown is clearly observed in this work. MOS device with Si3N4 film seems to have smaller degradation of gate-leakage current while it suffers shorter time to breakdown as compared to Ta2O5 samples. For devices with Ta2O5 film, a larger physical thickness suffers more reliability degradation from plasma charging damage because of the richer traps. Thus, a smaller physical thickness of high-k dielectric film is favorable for sub-micron MOS devices of ULSI application.