Surface Passivation of Silicon Using HfO(2) Thin Films Deposited by Remote Plasma Atomic Layer Deposition System

Hafnium oxide (HfO(2)) thin films have attracted much attention owing to their usefulness in equivalent oxide thickness scaling in microelectronics, which arises from their high dielectric constant and thermodynamic stability with silicon. However, the surface passivation properties of such films, particularly on crystalline silicon (c-Si), have rarely been reported upon. In this study, the HfO(2) thin films were deposited on c-Si substrates with and without oxygen plasma pretreatments, using a remote plasma atomic layer deposition system. Post-annealing was performed using a rapid thermal processing system at different temperatures in N(2) ambient for 10 min. The effects of oxygen plasma pretreatment and post-annealing on the properties of the HfO(2) thin films were investigated. They indicate that the in situ remote plasma pretreatment of Si substrate can result in the formation of better SiO(2), resulting in a better chemical passivation. The deposited HfO(2) thin films with oxygen plasma pretreatment and post-annealing at 500 °C for 10 min were effective in improving the lifetime of c-Si (original lifetime of 1 μs) to up to 67 μs.