Gate leakage properties on n-MOSFET with plasma oxidized and nitrided

In this paper, the material and electrical properties of newly developed gate dielectrics were investigated by SIMS depth profile. NMOS transistor structures were fabricated by thermally grown radical oxidation (TGRO) in a batch type thermal processor and densified by plasma re-oxidation in a slot processor, followed by post oxidation anneal process to cure the plasma damage and nitridation in N₂ plasma. Results show that most of the radical ions formed by plasma oxidation were redistributed in the bulk region of the TGRO layer, causing the increased density of oxygen, the reduced number of oxidation-induced defects, and the redistribution of dopants in the SiO₂/Si interface. A lot of electrons injected into the oxide are captured by positively charged traps with Coulomb trapping that lead to neutral trap centers. Also, the increased gate leakage current is caused by these trapping electrons in the SiON film following constant voltage stress. This result of leakage current behavior after electrical stress indicates that the nitrogen concentration is a key parameter that affects the Vg shift in the gate layer.