Plasma charging effect on MOS devices with gate dielectrics using high dielectric constant material

Plasma charging effects on the gate insulator of high dielectric constant (k) material in MOS devices was investigated because of the different trap-assisted conduction mechanism from that in the oxide. 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 more traps in the Ta₂O₅ bulk. Thus, a smaller physical thickness of high-k dielectric film is favorable for sub-micron MOS devices of ULSI application.