Characteristics of ZrO2 gate dielectric deposited using Zr t–butoxide and Zr(NEt2)4 precursors by plasma enhanced atomic layer deposition method

Scaling down of the microelectronic devices feature size is demanding high-quality ultra thin high-k gate dielectric as a potential replacement for SiO2 gate dielectric. Among the high-k materials, ZrO2 is considered as a potential alternative to SiO2 gate dielectric below 2 nm due to its thermodynamical stability as well as excellent electrical properties. For these reasons, we investigated ZrO2 films prepared by the normal atomic layer deposition (ALD) and plasma enhanced ALD (PEALD) techniques using Zr t–butoxide and Zr(NEt2)4 metal organic precursors. This study showed that ZrO2 films deposited by the PEALD method showed generally improved film qualities with relatively low-leakage current, negligible hysteresis, and low-carbon incorporation compared to those of the films deposited by the conventional ALD method. Also, ZrO2 films deposited using Zr(NEt2)4 precursor showed better film qualities than those of films deposited using Zr t–butoxide. Especially, ZrO2 films deposited using Zr(NEt2)4 with oxygen plasma showed the leakage current as low as about 2.5×10−9 A/cm2 with an equivalent oxide thickness value of about 1.4 nm. This study demonstrated the possible application of the PEALD technique for the high-quality ultra thin high-k gate dielectric film deposition.