On the suppression of hydrogen degradation in PbZr_(0.4)Ti_(0.6)O_3 ferroelectric capacitors with PtO_x top electrode

摘要

The effect of oxygen content in the sputtered Pt oxide (PtO_x, x=0.4～1), top electrode on suppressing the hydrogen degradation of ferroelectric capacitors of PbZr_(0.4)Ti_(0.6)O_3 (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 (N_2+H_2) annealing at 200℃ 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 PtO_x 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 PtO_x 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 electrode.