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.