On the suppression of hydrogen degradation in PbZr0.4Ti0.6O3 ferroelectric capacitors with PtOx top electrode

Abstract

The effect of oxygen content in the sputtered Pt oxide (PtOx, x=0.4∼1), top electrode on suppressing the hydrogen degradation of ferroelectric capacitors of PbZr0.4Ti0.6O3 (PZT) was studied. It was found that the ferroelectric property becomes significantly degraded along with a positive voltage offset in the polarization-field hysteresis loop after forming gas (N2+H2) annealing at 200°C of the PZT capacitors made with Pt top electrode. The leakage current in the degraded capacitors also greatly increases due to the reduction of Schottky barrier. However, the degradation of electrical property can be suppressed by using PtOx as top electrode, and the ferroelectric characteristics are well retained ever for capacitors with size shrunk down to submicron scale. The secondary-ion-mass spectroscopy and elastic recoil detection analysis reveal that the catalytic reaction of Pt in dissociation of hydrogen molecules from forming gas can be effectively interrupted by increasing the oxygen content in the PtOx electrode, and the property degradation induced from hydrogen segregation at the interface and incorporation with the PZT layer is thus suppressed. In addition to the superior hydrogen blocking capability, which prevents the detrimental effect of hydrogen doping, a high Schottky barrier is also obtained from the high work function of PtOx electrode.