Nitridation of atomic-layer-deposited HfO_2/Al_2O_3 stacks by NH_3 annealing

摘要

HfO_2/Al_2O_3 stacks are grown on Si (100) substrate by atomic layer deposition and then nitridized using ammonia (NH_3) annealing in the temperature range of 600-900 ℃. The effects of NH_3 annealing temperature on the structural and physical properties are investigated. HfO_2 phase changes from monoclinic to orthorhombic with the annealing treatment. Moreover, the increasing of the grain size and decreasing of the valence band maximum with increasing annealing temperature are demonstrated. In addition, the film annealed at 900 ℃ clearly shows that there exists an amorphous Al_2O_3 layer between partially crystalline HfO_2 layer and the Si substrate.