Effect of aliovalent impurities on the resistance switching characteristics of sputtered hafnium oxide films

In this work, the effects of various aliovalent impurities on the resistance switching characteristics of hafnium oxide (HfO2) films were investigated in conjunction with analyses of chemical bonding states and film microstructure. HfO2 films were cosputtered with magnesium, aluminum, and niobium by reactive DC magnetron sputtering. Doping with aliovalent elements caused the nonlattice oxygen concentration of HfO2 to increase and grain size to decrease. Also, post-thermal annealing induced a further increase of the concentration of nonlattice oxygen in the doped HfO2. Impurity doping improved the uniformities of the resistances of the low and high resistance states for cycled SET/RESET operations of titanium nitride/doped HfO2/platinum stacks, particularly for the magnesium-doped HfO2 films. (C) 2015 American Vacuum Society.