Electrical and material property enhancement in HfTaSiON-gated MOS devices by tuning Hf composition

High dielectric constant (high-k) materials, as a replacement for conventional gate dielectrics, have been proposed to overcome the problem of excessive gate leakage current. HfSiON is a potential high-k gate dielectric material, but the value of its dielectric constant is considered a little too low. In this work, we incorporate Ta into HfSiON to form a HfTaSiON gate dielectric. The influences of different Hf contents in HfTaSiON and various post deposition anneal (PDA) treatments were studied in detail. Experimental results show thatimprovements on the material and electrical properties of metal-oxide-semiconductor (MOS) devices such as crystallization temperature, interface quality between high-k dielectric/Si, hysteresis, stress-induced leakage current (SILC) and interface trap density (Dit) are achieved with incorporating a suitable amount of Hf in HfTaSiON high-k gate dielectric