We investigated the physical and electrical characteristics of a HfO2/ultrathin SiO2 (similar to 0.5 nm)/Si structure grown by a remote plasma atomic layer deposition (RPALD). The HF-cleaned Si substrate was oxidized by a remote plasma oxidation (RPO) process and yielded a similar to 0.5 nm thick SiO2 layer. HfO2 films were deposited on both H-terminated and RPO-treated Si substrates by the RPALD. During HfO2 film deposition, the RPO-treated sample showed more effectively retarded formation of initial Hf silicate layers than the sample on H-terminated Si. RPO treatment also improves electrical properties including hysteresis, effective fixed oxide charge density (Q(f,eff)) and equivalent oxide thickness (EOT).