Hafnium Oxide Based CMOS Compatible Ferroelectric Materials

The ferroelectric behavior of capacitors based on hafnium oxide dielectrics will be reported. Thin films of 7-30 nm thickness were found to exhibit ferroelectric polarization-voltage hysteresis loops when integrated into TiN-based metal-insulator-metal capacitors. A remanent polarization up to 25 μC/cm2 and a high coercive field of about 1 MV/cm was observed. Doping of HfO2 by different dopants with an atomic radius ranging from 110 pm (Si) to 188 pm (Gd) was evaluated and in all cases ferroelectric behavior was verified by polarization-voltage hysteresis, small signal capacitance-voltage characteristics, and for Si as a dopant also by piezoelectric measurements. Polarization retention and endurance was characterized on capacitor and transistor structures.