Thermally robust atomic layer deposited ZrO2 gate dielectric films upon the post-deposition annealing

Abstract

The effects of post-deposition annealing (PDA) on the electrical characteristics of ZrO2 and HfO2 gate dielectric films were investigated. After PDA at 600°C, the insulating properties of ZrO2 were improved, while those of HfO2 were deteriorated. The improved insulating properties of ZrO2 are attributed to both the negligible increase of interfacial layer (IL) thickness and the transformation of its crystalline structure to the tetragonal phase. The degraded insulating properties of HfO2 after PDA at high temperatures were due to the abrupt increase of IL thickness and the generation of current paths through grain boundaries. The different IL growth between HfO2 and ZrO2 after PDA could be understood from the different formation energy of oxygen interstitials in the two dielectric films.