Ultra-thin zirconium silicate films with good physical and electrical properties for gate dielectric applications

摘要

The need for alternative gate dielectrics to replace conventional SiO{sub}2 is increasing to facilitate further CMOS scaling. One of the most promising materials for use as an alternative gate dielectric is Zr silicate due to its thermodynamic stability on Si and its good interface quality with Si. In this study, ultra-thin Zr silicate films (45-60 A thick) with different Zr compositions have been deposited on Si using magnetron reactive co-sputtering. The Zr composition was kept below the stoichiometric value of about 16% to prevent precipitation of ZrO{sub}2 and to have Si rich films for better interface quality. Fibs were rapid thermal annealed in N{sub}2 ambient up to 900°C and Pt was used as the gate electrode. Electrical characterization of these films was done using HP 4156 and HP 4194 parameter analyzers. Based on these studies, we demonstrate Zr silicate films with equivalent oxide thickness (EOT) of less than 14 A with gate leakage significantly lower than SiO{sub}2 of similar thickness and hysteresis of < 20mV (in a sweep from -3 to 3 V). The films exhibit good thermal stability on Si even after 900°C annealing as shown by a minimal increase in EOT with annealing. TEM and XPS analyses show high quality Zr silicate films that remain stable and amorphous even at 900°C.