Interface effect on dielectric constant of HfO2∕Al2O3 nanolaminate films deposited by plasma-enhanced atomic layer deposition

Abstract

The effect of the interface between Al2O3 and HfO2 sublayers on the dielectric constant was investigated in HfO2∕Al2O3 nanolaminate films deposited using plasma-enhanced atomic layer deposition. After annealing at 700°C, the dielectric constants of the nanolaminate films with a sublayer thickness of 40Å or greater were the same as the calculated values for a series of capacitors consisting of amorphous Al2O3 and monoclinic or tetragonal HfO2. As the sublayer thickness was reduced to 10Å, the dielectric constant increased up to 17.7 because a thin Hf–O–Al mixture layer, of which the number increases drastically in the nanolaminate films with thin sublayers, is formed at the interface.