Electrical properties of HfTiON gate-dielectric metal-oxide-semiconductor capacitors with different Si-surface nitridations

Abstract

Electrical properties of HfTiON gate-dielectric metal-oxide-semiconductor (MOS) capacitors with different Si-surface nitridations in N2O, NO, and NH3 prior to high-k film deposition are investigated and compared. It is found that the NO-nitrided sample exhibits low interface-state density and gate leakage current, and high reliability. This is attributed to formation of a SiON interlayer with suitable proportions of N and O. The MOS capacitor with Hf0.4Ti0.6OxNy∕SiON gate dielectric stack (capacitance equivalent thickness of 1.52nm and k value of 18.9) prepared by NO surface nitridation has an interface-state density of 1.22×1011cm−2eV−1 and gate leakage current density of 6×10−4Acm−2 (Vg=1V). Moreover, only a small degradation of electrical properties after a stressing at 10MV∕cm for 3000s is observed for the NO-nitrided sample.