Atomic Layer Deposition of HfO2 Thin Films on Ultrathin SiO2 Formed by Remote Plasma Oxidation

Atomic Layer Deposition of HfO2 Thin Films on Ultrathin SiO2 Formed by Remote Plasma Oxidation

An ultrathin SiO₂ layer was grown on a H-terminated Si substrate by using remote plasma oxidation. The subsequent HfO₂ deposition on the ultrathin SiO₂ was achieved by a remote plasma atomic layer deposition (RPALD). During the HfO₂ film deposition and rapid thermal annealing (RTA), the ultrathin SiO₂ buffer layer effectively suppressed the formation of Hf silicate layers in the interfacial region. The Hf silicate layer in the interfacial region grew with increasing RTA temperature. The positive fixed oxide charges in the HfO₂ film were reduced with increasing RTA temperature. The thickness of the HfO₂ films with an ultrathin SiO₂ buffer layer showed a lower effective fixed oxide charge density (Qf,eff) due to the shift of the flat band voltage (VFB) toward the positive direction, compared to those with H-terminated Si. The thin interfacial layer of the HfO₂ films with a thin SiO₂ buffer layer resulted in a low equivalent oxide thickness (EOT) value. The leakage current densities of the HfO₂ films increased because of the crystallization of the HfO₂ film after RTA.

An ultrathin SiO₂ layer was grown on a H-terminated Si substrate by using remote plasma oxidation. The subsequent HfO₂ deposition on the ultrathin SiO₂ was achieved by a remote plasma atomic layer deposition (RPALD). During the HfO₂ film deposition and rapid thermal annealing (RTA), the ultrathin SiO₂ buffer layer effectively suppressed the formation of Hf silicate layers in the interfacial region. The Hf silicate layer in the interfacial region grew with increasing RTA temperature. The positive fixed oxide charges in the HfO₂ film were reduced with increasing RTA temperature. The thickness of the HfO₂ films with an ultrathin SiO₂ buffer layer showed a lower effective fixed oxide charge density (Qf,eff) due to the shift of the flat band voltage (VFB) toward the positive direction, compared to those with H-terminated Si. The thin interfacial layer of the HfO₂ films with a thin SiO₂ buffer layer resulted in a low equivalent oxide thickness (EOT) value. The leakage current densities of the HfO₂ films increased because of the crystallization of the HfO₂ film after RTA.